86 
 
 B27 
 
THE GIFT OF 
 
 !\.%A'\%3J>. 5\st\\^. 
 
 3777 
 
Cornell University Library 
 QE 86.M5B27 
 
 r crater (formerly called C.^^^^^^^^^ 
 
 Meteor 
 
 3 1924 003 933 060 
 
The original of this book is in 
 the Cornell University Library. 
 
 There are no known copyright restrictions in 
 the United States on the use of the text. 
 
 http://www.archive.org/details/cu31924003933060 
 
M EXE OR GRATER 
 
 (FORMERLY CAl-LED COON MOUNtAIN OR COON BUTTE) 
 
 HORfHERN GE^ ARIZONA 
 
 D. M. BARRINGER 
 
 This paper urns read before the National Academy of Science^ at 
 
 its Autumn Meetbig at l^rinctton University, 
 
 November 16th, 1909. 
 
m m mimmmimoimmm. 
 
 (six miles south of sunshine station A.T.& S.F.R.R. COCONINO COUNTY. 
 & IN SECTIONS 13 & 24.T.I9.N.R.I2>S E.) 
 
 rMPEWYIFIM 
 
mwm mim i# mmiim lisiiiyiioi of mam^ mum m fummimy 
 
 N.B.SOMEROCKFRftGMlNTSHRIEBEEN THROWN AS FAR AS TWO MILES FROM THE CRATER. THIS MAP MERELY SHOWS MANNER OF DISTRIBUTION AND 
 RELATIVE QUANTITY OF MATERIAL NEAR THE CRATER . VERY MUCH MORE MATtRlAL HAS BEEN THROWN TO THE SOUTH CSENERALLY SPEAKING) 
 THBN ELSEVWERE, I.E. THE MASS OF FIOCK FRAGMENTS 15 MUCH THICKER THERE THAN ELSEWHERE AND THE ROCK HAS BEEN MORE FINELY 
 CRUSHED. THE ROCK FRAGMENTS SEEMJOJAVE BEEN THROWN FURTHEST TO THE N.E. BY E .WHERE THEY THINLY COVER A LARGE AREA. 
 
 ^S°--€2i^^ 
 
 
 LEGEND). >.., -....w,.?..."- ^_ '^'<i.-.>» 
 
 CRATER RIM. '~''^~-' S 
 
 ■■•" LOWER LIMrrOFBULK OF EJECTED MATERIAL WHICH FORMS TO A LARGE EXTENT THE SO CALLED^MOUJ>tfAIN .THISLINENECESSA'raLYAFPROXIMftTE, 
 LIMESTONE FRAGMENTS, THE MOST COHERENT ROCK THROWN OUT OF THE C RATER ■ 
 FIELDS OF BIG LIMESTONE BOULDERS ON THE EAST AND WEST SLOPES OF ffitlVreUNTAlN.^^ / -< __, 
 
 WHITE OR GRAY SACCHAROIDAL SANDSTONE FF?AGMENTS. THESE FREQUENTLY SHOW CROSS 8EDf)l1!|G . -^■' / "" .J-''^ 
 
 BROWN SANDSTONE FRAGMENTS a BROWN SAND DUE TO THEIR DISINTEGRATION . MUCH OF THIS SAND HAS BEEN DRIfT-TD TO THE EASTWARD 
 BY THE PREVAILING WINDS. "-Vv, '"""'•■'■— ^~. -*-- ^^ -~^^J ' '_,y"' 
 
 THIN SHEETS OR INDIVIDUAL MASSES OF EJECTED LIMESTONE FA,R OUT ilK THE PLAIN. ""THESE SCATTERED FRAGMENTS ARe" FOUND la MILES 
 FROM THE CRATER RIM TO N.E:.— |5^T0 2 MILES EAST AND ABOUT ONE MILE S.E.— MAF|,JOO SMALL TO SHOW THEIR 
 
 DISTRIBUTION EXCEPT IN A GENERAL WAY. 
 
 m US RIDUCtO »PIH!5CSltl8 I230P -UN. 
 
 copiia sr NOVEMBER BOS. 
 
 JAMES D. COCHRANE CE. A 
 
 PHILADELPHIA. RA. f 
 
y^P SHOWiG iSTiiUTiOli OF ilTMKie iMMttl MOUIP 
 
 , CANYON DIABLO STATION. 
 
 ilTliK il^IlK COCOffliO CO., MIIOHA. 
 
 m THIS REDUCED MAP THE SCALE IS^z -ONE MILE, 
 THW IS THE Vmii mi ONE MILE APART . 
 
 NSHINE STATION. 
 
 AJ.hSf.RR. 
 
 METEOR P.O 
 N 
 
 + 
 
 -LSSgSOS' 
 
 METEORIC IRONS(ORDINARY CANYON DIABLOSIOtRITESjFROMIO^TO 547* DISCOVERED BY STANDARD IRON COMPANY. 
 
 . ■ FROM lO^TO 1000* DISCOVERED BY MEXICANS EMPLOYED BY F.W.V0L7 ET AL, PREVIOUS TO ACQUISITION Of PROPERTY BY S.I. CO. 
 
 > SMALL. DISCOVERED BY S.I. CO. THOUSANDS OF THE SMALL IRONS FOUND. HENCE DISTRIBUTION ONLY APPR0XIMATE0.(tHE5E ARE GENERALLY ONLY A 
 FEW GRAINS OR OUNCES IN ViCISHT, IRONS WEIGHING FROM ONE TO TEN POUNDS FOUND ONLY OCCASIONALLY.) 
 
 LARGE IRREGULAR MASSES OF METEORIC IRON OXIDE OR LARGE SHALE BALLs" FROM lOo'!: TO 300* IN WEIGHT, DUE TO OXKWION OF METEORIC IRON RICH IN CHLORINE AND 
 SULPHUR OR SHALE BALL IRON. 
 
 SMALL BROKEN FRAGMENTS OFMETEORIC IRON OXIDE OR "iRON SHALe' CA FEW GRAINS OR OUNCES, BARELY A POUND IN WEIGHT) THOUSANDS OF SUCH REOES FOUND, 
 HENCE DISTRIBUTION ONLY APPROXIMATED. 
 
 COPltO BY 
 
 JAin£S D. COCHRANE C.E 
 PHIlADELPHIb PA. 
 
 NOVEMBER 1908. 
 
METEOR CRATER 
 
 (formerly CALLED COON MOUNTAIN OR COON BUTTE) 
 
 IN NORTHERN CENTRAL ARIZONA.* 
 
 It affords me pleasure to attempt to describe briefly some of the 
 features of Meteor Crater, Arizona, the origin of which I have been 
 privileged to be chiefly instrumental in discovering. 
 
 I shall subdivide my paper into six headings as follows : 
 
 First.' Topography and geology of the region immediately sur- 
 rounding the crater. 
 
 Second. Description of the main features of the crater itself, 
 including a description of the ejected rock fragments and of the two 
 kinds of metamorphosed sandstone known to us as "Variety A" and 
 ■'Variety B." 
 
 Third. The kinds of meteoric iron and meteoric Iron oxide 
 found on the outside plain and among the ejected rock fragments 
 on the outer slopes of the crater rim. 
 
 Fourth. The kinds of meteoric material which have been found 
 to exist in the depths of the crater. 
 
 Fifth. Conclusions. 
 
 Sixth. What has become of the projectile? 
 
 TOPOGRAPHY AND GEOLOGY. 
 
 The topography immediately around the crater is that of a more 
 or less level rocky plain with a very thin covering of soil. In places 
 the soil is entirely absent, owing largely to the violent winds which 
 prevail at certain sea.sons of the year. There are no trees on this 
 plain except many stunted cedars on a rather large area^ several 
 miles to the south, and except a sparse growth of cottonwoods and 
 walniits along the water courses. The water flows in torrents 
 through the deep box canyons in the flood season, but for the rest 
 of the year there is little or no water in them, owing to the lack of 
 rain. The slightly rolling plain is sparsely covered by the usual sage 
 brush and grass characteristic of this desert region. Portions of the 
 plain, as in the case of the exact location of the crater, were covered 
 at the time it was made, probably in historical times, as now, by a 
 thin bed of purplish red sandstone having in places a shaly structure. 
 This stratum of sandstone, like all the undisturbed strata underneath 
 it, is horizontal. Other portions of the plain, especially to the; west- 
 ward of the crater, are marked by the outcroppings of the uppermost 
 layers of the underlying Aubrey (Carboniferous) limestone, which is 
 well shown not only in the crater walls, but in the neighboring gorge 
 of Canyon Diablo, two and one-half miles distant to the west. 
 Dotted here and there over the plain, as accidents of erosion, are 
 many small, isolated buttes of the purplish red sandstone showing 
 the contact between it and the limestone. There are no eruptive 
 rocks of any sort nearer than Sunset Mountain some nine miles 
 distant. This is formed by an old volcano and the lava which flowed 
 from it. To the northwest and west some forty odd miles are the 
 San Francisco Mountains, with their numerous craters and the great 
 
 *This paper zvas read before the National Academy of Sciences 
 November i6th, ipop. 
 
flows of lava which poured out from them over the surrounding area 
 of level sedimentary rocks. 
 
 The rocks with which we are immediately concerned are, generally 
 speaking, the Grand Canyon series, and are as follows: First, some 
 40 or 50 feet of the purplish red shaly sandstone above referred to. 
 Underneath this 250 to 300 feet of a yellowish gray, arenaceous lime- 
 stone. Underneath this there is a stratum of about 1000 feet in 
 thickness (as nearly as we can estimate it) of what we know as the 
 white or gray saccharoidal sandstone, in places cross bedded. This 
 stratum is beautifully shown in the walls of the Grand Canyon of the 
 Colorado some 70 miles distant, and is known there as the White 
 Wall or Cross Bedded sandstone. 
 
 As at the Grand Canyon this white or gray sandstone is under- 
 laid by a dark red sandstone stratum, known as the Red Beds or the 
 Red Sands, of about one thousand feet in thickness at the Grand 
 Canyon and of unknown thickness at Meteor Crater. 
 
 One point to which I wish particularly to call attention is that we 
 know from our drilling and from the ejected rock fragments thai 
 the lower two hundred feet of the white or gray saccharoidal sand- 
 stone (which for the greater part of its thickness is a sandstone 
 which is singularly white and of exceptional purity) is largely com- 
 posed of sand grains of yellowish, and finally immediately above the 
 Red Beds of brownish red color. This point is of importance, as 
 will be seen later. The whole stratum is a loose textured, incoherent 
 sandstone, and this is particularly true, so far as we know, of its 
 lower portions just referred to. 
 
 With the much more compact Red Beds sandstone immediately 
 underneath this stratum we are not immediately concerned, for no 
 piece of this stratum has been thrown out to form a part of the 
 great mass of ejected rock fragments comprising in a large measure 
 the elevation formerly known as Coon Mountain or Coon Butte. 
 Our drill, however, has penetrated these Red Beds in a number of 
 places. I have with me samples of the drill cores and a complete log 
 of all the drilling. This sandstone has been found to be in place, to 
 be unaltered and to be occupying a horizontal position. These facts 
 are indisputably shown by the cores brought up by the drill. In short 
 it is, so far as we now know, practically certain that this Red Beds 
 stratum was not particularly affected when the crater was made, 
 certainly not to the extent of having been thrown out, violently dis- 
 • turbed, or having been metamorphosed. In my paper read before 
 the Academy of Natural Sciences of Philadelphia four years ago I 
 made the mistake, owing to the similarity in color, of thinking that 
 a portion of the Red Beds had been thrown out. I now know that 
 the brownish red fragments are from what we term the brown sand- 
 stone, above referred to, which overlies the Red Beds. 
 
 The drilling of some twenty five holes in the generally central 
 portion of the floor of the crater has absolutely demonstrated the 
 general correctness of the above statements. I should add that no 
 piece of igneous or eruptive rock has been encountered by us. in 
 connection with our work, or exists in place within less than nine 
 miles of the crater. 
 
 GENERAL DESCRIPTION OF THE CRATER AND 01? THE EJECTED ROCK 
 
 FRAGMENTS. 
 
 It should be remembered that the word crater is used simply for 
 
want of a better tefm to describe a great basin like hole in the orig- 
 inally horizontal strata, and because in shape it is not at all unlike a 
 volcanic crater. We now definitely know, and I think I shall be 
 able to show you, that it was not produced by any volcanic agency. 
 
 I have had a very accurate map made of the crater, as well as a 
 necessarily more or less rough sketch showing the distribution of 
 the ejected rock fragments. I have also had made a much more 
 accurate map showing the distribution of the meteoric material con- 
 centrically surrounding the crater. A careful study of these maps, 
 which are printed herewith, should be made by those who are inter- 
 ested in the various questions which will be discussed in this paper. 
 
 The crater, as will be seen by referring to the map, is nearly 
 round and is, roughly speaking, about 4000 feet, or something over 
 three-quarters of a mile, in diameter. It is of an average depth 
 from the rim to the interior central plain, or more or less level floor, 
 of about 570 feet. The limestone and sandstone strata exposed m 
 the walls dip away from the center of the crater at varying 
 angles, as shown on the map. The fact that the strata are uplifted in 
 this way of course contributes to form the rim and the elevation 
 heretofore known as Coon Mountain or Coon Butte. The compact 
 limestone bed is very prominent in the crater wails, and where it is 
 nearly horizontal causes the cliffs to be nearly perpendicular. A 
 very interesting feature in the southern portion of the crater is that 
 for a distance of half a mile, measuring around the rim, this lime- 
 stone and the underlying sandstone have been vertically lifted as a 
 mass more than one hundred feet out of their original position. 
 Careful aneroid measurements show that the uplift of this great mass 
 of rock is 105 feet. I mean measuring from the top of the perfectly 
 level limestone bed, where we know it to be in place on the outside 
 level plain, to the top of the same limestone bed, where we know it 
 to be out of place in the south wall of the crater, but where it is also 
 lying level. The cause of the uplift of this tremendous weight of 
 rock (probably some 20 to 30 million tons) may be found in the fact 
 of the meteoric mass having wedged itself underneath, or in the 
 development underneath it of a vast amount of shattered rock, or by 
 the formation beneath it of great quantities of what we know as 
 Variety A and Variety B of the metamorphosed sandstone- Directly 
 opposite in the northern rim of the crater, between W. N. W. and 
 _N. W. to N. N. E. (the line "B — B" on the map passes nearly through 
 the center of it) there is to be seen, when the observer approaches 
 from the north, a very noticeable low place or depression in the crater 
 rim. Attention is called to the fact that this is not only opposite to 
 but that it coriTsponds quite closely in length with the great vertical 
 Uplift of the strata in the southern wall. It has been suggested that 
 the inrush of the air accompanying the projectile may have produced 
 this low place in the northern rim. It is partly shown in one of the 
 general views of the crater. The southern cliffs are also fairly well 
 shown in these photographs. 
 
 The ejected sharply angular rock fragments are of all sizes and 
 shapes, from great masses of limestone weighing perhaps m excess 
 of 4000 tons, down to microscopic particles of crystalline quartz 
 which we know as "silica" or rock flour, as it has been aptly called. 
 There are a great many million tons of this latter material. It 
 probably forms fifteen or twenty per cent, or more of the entire 
 material thrown out of the crater. It is absolutely certain that this 
 
rock flour is pulverized sandstone. In no case are the little micro- 
 scopic, sharply angular, particles of crystalline quartz larger than one 
 of the very small, water worn grains of quartz which compose the 
 white or gray sandstone. A very large proportion, if not most of it, 
 will pass through a 200 mesh screen, the finest of all wire screens. It 
 is very interesting material, and in my opinion cannot have been 
 formed, much less distributed as it is at present, by any other agency 
 than by the impact of a body or a group of bodies falling out of space, 
 and moving at high speed. It fills in a large degree, with the included 
 rock fragments great and small and the metamorphosed sandstone 
 which will be described, the lower portion of the crater, and is the 
 material which forms in a large degree the outer slopes of the rim, 
 where in places it is admixed with the larger angular limestone and 
 sandstone fragments very abundantly. In other places it is com- 
 paratively free from them. In some places it looks as if it had 
 welled out of the crater like flour out of a barrel. In places great 
 quantities of the metamorphosed sandstone (principally Variety A) 
 have been expelled from the crater and have disintegrated into this 
 silica or rock flour. We have specimens of this metamorphosed or 
 partly metamorphosed sandstone showing a gradation from the 
 almost unaltered white or gray sandstone down to this rock flour. 
 Some are coherent, others are incoherent, some contain a large per- 
 centage of unbroken water-worn quartz grains; there are others 
 in which it is impossible to find a single unbroken sand grain. These 
 specimens must be seen to be appreciated. Time does not permit me 
 to emphasize the fact that these in themselves, and entirely apart 
 from the great amount of other proof, present incontrovertible proof 
 that this crater could not have been produced in any other way than 
 by the impact of a projectile falling out of space and moving at high 
 speed. The rock flour is exposed by erosion in a number of places 
 on the south rim, that is to say, the south slopes of the "mountain." 
 At one place in particular there is an arroya some two or three hun- 
 dred yards long and some ten to twelve feet deep, where this very 
 white rock flour is naturally exposed. In analysis it often shows 
 upwards of 98 and 99 per cent, silica. 
 
 The amount of rock dislodged and partly thrown out of the crater 
 has been estimated at over three hundred million tons. A vast 
 amount of the surrounding rock in addition has been violently dis- 
 turbed. (In passing it should be noted that it is practically impos- 
 sible to estimate accurately the amount of work done or energy 
 expended ; almost as impossible as it is to estimate the speed at which 
 the projectile was moving when it struck. Therefore it becomes 
 extremely difficult to make a reliable estimate as to the weight of 
 the projectile. As it seems to me, all that we can know with cer- 
 tainty is that its weight must have been very great.) It is very diffi- 
 cult, if not impossible, to form a correct estimate of the amount of 
 the dislodged and ejected material. I think that this can be clearly 
 shown to any one who will visit the locality. In the first place, 
 it is next to impossible to know without innumerable shafts 
 just how deep it is to rock in place, frequently tilted and broken 
 strata, on the outside of the rim. Again it is impossible to know 
 without most complete exploration what the shape of the invisible 
 true bottom of the crater is, inasmuch as it is filled for about one-half 
 of its depth with the rock fragments which have rolled back into it and 
 
with some 70 to 90 feet of lacustrine or lake sediments formed at a 
 time when the bottom of the crater was the bed of a small lake.*. Nor 
 is it possible to estimate the amount of talus at the base of the .lime- 
 stone cliffs. Finally there can be no doubt that enormous quantities 
 of the finely divided rock flour have been blown away from the slopes 
 of the so-called mountain by the violent winds that rage in the 
 locality. 
 
 Some of the rock fragments have been ejected to an extreme dis- 
 tance of about one and one-half to two miles from the crater. These 
 are pieces of compact limestone weighing from fifty to several hun- 
 dred pounds. The larger fragments, and especially the very large 
 fragments, are distributed rather closely around the crater, say not 
 to exceed a quarter of a mile from the rim. As will be seen from 
 the map, there are two remarkable fields of big boulders, as they 
 are locally terme'd, or very large angular limestone fragments, weigh- 
 ing hundreds and even thousands of tons, opposite to each other, one 
 on the eastern side and one on the western side of the crater. The 
 symmetry which is seen in the walls of the crater and in <he ejected 
 rock fragments is very remarkable and furnishes in itself one of 
 the many proofs against a volcanic origin of the crater. By con- 
 sulting the map you will notice that not only are these very large 
 rock fragments on the outside distribated more or less symmetrically, 
 but that, commencing at a point which we will name as north north- 
 west, the strata exposed in the walls of the crater gradually increase 
 in dip as you go around the crater in either direction to the south, 
 from 5 degrees up to vertical and in one place they are slightly over- 
 turned. The greatest amount of ejected material lies on the south 
 slopes of the mountain, where it is also more comminuted than else- 
 where. This symmetry along the line "B — B" shown on the map 
 is not accidental and would be impossible if a steam explosion had 
 caused the crater. Then there are several interesting spurts or jets 
 of rock fragments to be observed on the outside rim from N. N. W. 
 to E. S. E., which are composed entirely of white sandstone frag- 
 ments overlying limestone fragments. These jets of sandstone 
 fragments are of great interest. It does not seem probable to me 
 that they could have been made in any other way than by the impact 
 of a projectile. They can be duplicated by such an impact, that is 
 to say, by a rifle bullet fired out of a high power rifle, but they cannot 
 be duplicated by any sort of a gas explosion. Any one who is 
 familiar with the action of explosives will, I think, bear me out 
 in this when he has visited the locality. An explosion from beneath 
 (such as the Hell Gate explosion or the explosions employed to 
 break up the "nitrate" in Chile) separates and scatters the material 
 in a very different and characteristic way. The spurts or jets of 
 rock fragments could not, it seems to me, have been produced by an 
 explosion from beneath. Again, the rock fragments on the outside 
 rim, while often intimately admixed over small areas, always 
 lie, when considered in a large way, in the reverse order of their 
 geological occurrence when undisturbed. That is, the limestone 
 fragments are on top of the purplish red sandstone, and the white 
 
 *Dr. W. H. Dall will soon examine the \ fossil shells found in 
 these sediments with the object of determining as nearly as possible 
 the age of the sediments. 
 
 Dr. Dall has smce reported that these ' 'are all recent species, local 
 to the region of the southwestern U. S." This is in further corrobora- 
 tion of a statement made in a previous paper (Proc. Acad. Nat. Sci. 
 of Phila.-Dec 1903 -p. 868) that the crater is of comparatively 
 recent origin and that probably only a few thousand years at the most 
 have elapsed since it was made by the impact of the head of a very small 
 comet. 
 
sandstone fragments are on top of the limestone fragments; all 
 of which is strongly suggestive of the ploughing effect of a pro- 
 jectile. In this connection there are on the surface of the south- 
 east rim thousands of tons of brown sandstone fragments, or 
 bro>vn sand due to their disintegration. As above stated, we 
 know by our drilling that this brown sandstone is found only in 
 the lower portion of the white or gray saccharoidal sandstone 
 stratum. Petrographically, as Dr. G. P. Merrill has pointed out, it 
 is the same rock and is different from the somewhat darker and 
 much more compact sandstone of the underlying Red Beds, The 
 fact that this very large amount of brown sand and brown sandstone 
 fragments, stratigraphically the lowest of all the rocks ejected, is found 
 in quantity at this particular locality on the rim and nowhere else, 
 and is on top of the other ejected material, is significant, and it should 
 not be forgotten is in absolute accord with the ' symmetry above 
 referred to. These brown sandstone fragments could not, it is 
 argued, lie on top of the white sandstone fragments, and they in 
 turn could not lie on top of the limestone fragments if a steam 
 explosion had caused the crater. 
 
 1 have the permission of Professor William F. Magie to state 
 that the map of the crater which has recently been made is as correct 
 as it has been possible to make it, and that it has not been distorted 
 in any way in order to fit any theory. I am glad to say that Pro- 
 fessor Magie was able to spend two weeks at the crater with me this 
 summer and to examine very carefully all the phenomena in connec- 
 tion therewith many of which the space of this paper will not permit 
 me to dwell upon. 
 
 THE METAMORPHOSED SANDSTONE. 
 
 The metamorphosed sandstone is of peculiar and of great interest. 
 It is of two varieties. What we have termed Variety A consists 
 of angular fragments of undoubtedly original sandstone, still show- 
 ing the bedding planes, but often with strongly marked slaty structure 
 at more or less right angles to the bedding planes, which slaty struc- 
 ture can be due only to the exercise of very great lateral or perhaps 
 radial pressure. Dr. J. W. Mallet was the first to assure me that this 
 rock was certainly of terrestrial origin. I had submitted one of the 
 first specimens found in the main shaft, which we attempted to sink 
 in the center of the crater, to him for examination, since I had never 
 seen a rock like it. The utter destruction of the individual sand 
 grains and the superinducing of this more or less vertical slaty struc- 
 ture by pressure before the rock was dislodged and thrown out, is 
 simply unexplainable on any other theory than that of terrific and 
 sudden shock, with waves of concussion and pressure radiating out- 
 wardly; all of which is again absolutely opposed, of course, to the 
 steam explosion theory of origin. That this rock was heated highly 
 there can be no doubt, but that it was quite dry at the time it was 
 metamorphosed there also seems to be no doubt. While I have 
 found it to contain now and then some unbroken sand grains, it is 
 composed almost entirely of minute fragments of crystalline quartz, 
 each of them smaller than one of the original sand grains of which 
 the rock was composed. The bedding planes are still well shown, and 
 an interesting fact is that they are not always at right angles, but 
 are frequently at different oblique angles, to the slaty structure above 
 
referred to. This fact alone practically necessitates this metamor- 
 phosed rock having been made by a projectile advancing through the 
 rock strata of which these are fragments. The following simple 
 
 diagram will show what is meant. 
 All of this was recognized almost 
 as soon as these peculiar rock 
 specimens were found, and was 
 discussed at the time in corre- 
 spondence with Dr. Mallet. • A 
 
 , specimen of Variety A, how- 
 ev.er, to which Dr. J. C. Branner 
 
 , called attention when he was at 
 the crater several years ago, in- 
 cludes small areas of what we 
 have known as Variety B, which is a vesicular metamorphosed 
 rock, looking not unlike pumice stone, in which by far the greater part 
 of the metamorphosed quartz is amorphous and not crystalline. 
 Many angular fragments of this, interesting metamorphosed sand- 
 stone have been found. When examined under the polariscope these 
 vesicular pieces of Variety B show little particles of crystalline quartz 
 scattered now and then throughout the mass of amorphous quartz, 
 of which the rock is almost wholly composed. 
 
 There is, so far as we know, vastly more of Variety A than of 
 Variety B, but much of the former, since it was expelled from the 
 crater, has disintegrated into what we know as silica or rock flour, , 
 and we have only been able to get good specimens, especially those 
 showing the slaty structure, from the bottom of the main shaft which 
 we attempted to sink in the middle of the crater. One of the drill 
 holes (No. 7), however, showed some fifty-odd feet of Variety A 
 at the depth of from 530 to 584 feet. 
 
 In passing I should say that it was found impossible to sink our 
 main shaft more than 222 feet, or about 25 feet below water level, 
 because of the peculiar quicksand, formed by the water saturated 
 silica, which we encountered; also that, in my judgment, it will be 
 impossible to properly explore the depths of the central portion of 
 the crater until we shall have removed the water which we now know 
 fills its lower portion. Fortunately this part of the crater has been 
 fairly well prospected by the drill. The water seems to be held in 
 the quicksand above referred to and to be confined to the crater, from 
 the catchment area of which it is probably derived. It does not seem 
 to exist in quantity in the surrounding undisturbed sandstone. It 
 is probable that a shaft can be sunk in the crater through the talus 
 and close to the walls, where we know the rock fragments to be much 
 
 " lat'ger than in the central portion, and where there is also much less 
 silica or rock flour. 
 
 In one of the small- prospecting shafts in the bottom of the crater 
 which was carried down only to water level, and subsequently also 
 quite far down on the outer slopes of the rim, we have found a few 
 remarkable specimens of what we know as Variety B of the meta- 
 morphosed sandstone. These certainly represent aqueo-igneous 
 fusion, as Dr. Mallet was the £rst to point out. As in the case of 
 Variety A the lines of sedimentation are still more or less distinctly 
 preserved in this peculiar vesicular metamorphosed rock. The bed- 
 ding planes, however, are distorted and are frequently lifted up one 
 from the other, with minute filaments of amorphous quartz connect- 
 
ing the two. The whole appearance of this very white rock is not 
 unhke that of very Hght, spongy bread. As shown by the drill, it is 
 often sparingly admixed in the depths of the crater with bluish 
 opalescent quartz, and in one specimen, secured from No. 2 prospect- 
 ing shaft, a mass of Variety B shows on its outside a very consider- 
 able quantity of this opalescent quartz, which has apparently been 
 liquid. Now Variety B, I assume, was not heated much more highly 
 than Variety A, but, owing to the presence of water, semi-fusion, 
 or, as in the case of the opalescent quartz, complete fusion could take 
 place, which was impossible in the case of Variety A. It is very 
 wonderful to think how this vesicular metamorphosed rock was 
 formed in a small fraction of a second and was afterwards hurled 
 to the outside plain, as has occurred in a few cases. Practically all 
 of the pieces of Variety B which have been thrown out of the crater 
 have been found between the spurts of white or gray sandstone, and 
 have been confined to a rather small area about 1200 feet from 
 the rim to. the E. N. E. Variety B might be considered 
 to be quite similar to geyserite were it not for two things 
 — first, as Professor S. L. Penfield showed, while almost wholly 
 composed of amorphous quartz, it undoubtedly contains some of the 
 crystalline fragments of which Variety A is practically wholly com- 
 posed, and second, it is now and then smeared with or otherwise 
 associated with the bluish opalescent quartz, which undoubtedly rep- 
 resents more perfect fusion of the original sandstone. There is reason 
 to think that portions of Variety A and Variety B were formed close 
 to the advancing projectile, since fragments have been found which 
 are stained with the oxides of iron and nickel. They also represent 
 the rock which was most highly heated and seems to have been 
 subjected to the greatest pressure. 
 
 The specimens of Variety B, which are often so light as to float 
 on water, must be seen to be appreciated. When they are studied 
 carefully they, like the specimens of Variety A, will be found to 
 constitute an irrefutable argument against any volcanic or steam 
 explosion theory of origin of the crater. 
 
 I should perhaps add at this point that I have failed to see any 
 evidence of the action of steam except in a very small way in forming 
 Variety B. It is not necessary to presuppose an explosion on a large 
 scale of any sort. As I read them, the facts are all against any 
 explosion except those represented by small and relatively unim- 
 portant puffs of steam where there was water in the sandstone. 
 
 THE KINDS OF METEORIC IRON AND IRON OXIDE FOUND OUTSIDE OF 
 
 THE CRATER. 
 
 The ordinary Canyon Diablo iron meteorites and their composition 
 (about 91 to 92 per cent, iron and about 8 per cent, nickel) are well 
 known to the scientific world; also the fact that they contain micro- 
 scopic diamonds. We were the first to show that they contain plati- 
 num and iridium to the extent of from y^ an ounce to % of an ounce 
 per ton of iron. No description of the specimens of this class of 
 meteoric iron is necessary, except to point out that they are not 
 readily oxidizable. Hundreds of such pieces had been shipped from 
 the region in the vicinity of the crater to museums all over the world 
 before we secured possession of the property. Before then, and 
 
before we had proved the simultaneify in time between the fall of 
 this and the other class of meteoric iron, hereafter described, and 
 the formation of the crater, it was not known, however, that the 
 crater was practically in the exact center of an area on which lay 
 many more meteoric iron specimens than have ever been found oh 
 all the rest of the world's surface. Literally, many thousands of such 
 specimens have been found. The map which shows the distribution 
 of tlie meteoric material will bring out this remarkable fact. This 
 ■map has been carefully made and may be considered as accurate as 
 such a general map can be. 
 
 It will show that no meteoric material has been found further than 
 five and one-half miles away from the crater — over twice as far as 
 the ejected rock fragments are found — and that it increases in 
 abundance as one draws near to the crater. It is practically proved, 
 as will be seen, that most of the individuals of this so-called 
 "shower" do not represent the effect of the bursting in the atmosphere 
 of an enormous siderite, as is commonly supposed. 
 
 Until we acquired. possession of the property and until we began 
 to sink shafts and make cuts in the silica and rock fragments on the 
 slopes of the mountain, it was not known that this ejected material 
 contained meteoric iron. This exploration work discovered another 
 variety of meteoric iron, previously unknown, which is represented by 
 what are now known as "shale balls." These (and there can be no 
 doubt of this) are generally rounded or globular disintegrating 
 masses of meteoric iron and nickel oxide, many of them containing 
 solid nickel iron centers. With others, I had at first thought that 
 the iron and nickel oxide of which these shale balls are sometimes 
 entirely composed, and with which they are always covered when 
 they have an iron center, was due to the burning of these meteorites 
 in their passage through the earth's atmosphere. Professor O. C. Far- 
 rington was the first to take issue with me on this point, and I am now 
 convinced that he was right. In fact, it is now proved that this iron 
 oxide or shale (the name was given to it because of the peculiar shaly 
 structure so often noticed in this material) is due to terrestrial oxida- 
 tion of this peculiar shale ball iron, which it must be understood is 
 chemically different from the ordinary Canyon Diablo siderites in 
 that it contains very small quantities of chlorine, which is practically 
 absent in the latter. Otherwise in chemical analysis they are quite 
 similar. They also contain microscopic diamonds and, I assume, a 
 small amount of platinum and iridium. We have encountered in 
 our shafts and cuts on the outer slopes of the mountain more than 
 a hundred of these so-called shale balls. I call attention again to 
 the remarkable fact that they are never angular, but as stated, always 
 seem to be rounded, and globular or oval in shape. Sometimes they 
 are pear or almond shaped. They are frequently found on the out- 
 side plain entirely converted by terrestrial decomposition into iron 
 shale, yet retaining the general outline of their original shape. 
 When sawed in two these specimens are very interesting. What 
 appear to be Widmanstatten figures can still be dimly seen in some 
 of them. The iron shale with which they are covered is often 
 exactly similar, even to the characteristic roughly triangular shape, 
 to many of the thousands of pieces of iron shale which are strewn 
 over the plain. The largest shale ball with an iron center which we 
 have so far found weighed some forty odd pounds. Those with 
 
iron centers have been found in the rock fragments and siHca on the 
 slopes of the mountain, where they have been protected from com- 
 plete oxidation, but they have not been found at any considerable 
 depth in these ejected fragments so far. They are usually found 
 in the upper portion of the ejected material. The deepest found was 
 at 27 feet. It is interesting that they are overlaid in no particular 
 order by limestone and white and red sandstone fragments which 
 come from the adjacent crater, and it is certain that they and the 
 rock fragments overlying and underlying them have not been moved 
 appreciably since the time they came to rest in their present surround- 
 ings. Where they lie in the almost snow white silica they have in 
 decomposing stained it for only a few inches around each specimen. 
 The evidence -is all against their rounded or globular shape being due 
 to terrestrial decomposition. It is interesting that so far no piece of 
 the ordinary unoxidizable Canyon Diablo iron has yet been found 
 deeply embedded in the silica on the slopes of the mountain, but 
 always on top of it, that is on or very near the surface, where many 
 hundreds of specimens have been found. I have no completely 
 satisfactory explanation to offer for this fact. 
 
 An interesting discovery was made in making a trench for the 
 pipe line from our reservoir in Canyon Diablo. A piece of iron was 
 found, one end of which was composed of the shale ball variety o? 
 iron and the other end of the ordinary Canyon Diablo siderite 
 variety. Other specimens show the same thing on a smaller scale. 
 One has been found with quite a large amount of iron shale adhering 
 -to it ; others with a less- quantity. It is therefore certain that these 
 two classes of irons have frequently formed part of the same mass, 
 probably grading one into, the other. It is certain that what we 
 know as the shale ball variety of iron frequently disintegrates or 
 oxidizes with remarkable rapidity, probably in proportion to the per- 
 centage of chlorine which it contains. For example, a solid iron 
 center which we dug out of the silica and rock fragments on the 
 outer slopes of the crater rim three years ago, so solid that it could 
 not be more than dented with a heavy sledge when placed on an anvil, 
 is to-day represented by a lot of iron dust or rust, some of which 
 is the so-called iron shale, and a few pieces of iron. 
 
 Most of these shale balls, when exposed to the action of the 
 atmosphere, have a tendency to disappear rapidly, or to oxidize 
 into hard compact iron shale, but when not so exposed, as when 
 embedded in the silica, they oxidize very slowly. It is very likely, 
 from the association of the pieces of the so-called iron shale, 
 which is found in great abundance on the plain for several miles on 
 all sides of the crater, and from the fact that this hard, compact 
 iron shale often shows more or less curvature (indicating that it 
 in all probability had been once a part of an unoxidized shale ball iron 
 meteorite), that the surrounding plain was strewn with perhaps thou- 
 sands of these unoxidized shale ball iron meteorites a few minutes 
 after the impact. It is also very nearly proved that at least most of 
 the small Canyon Diablo irons represent the residual unoxidizable 
 portions of such shale ball iron meteorites, the oxidizable portion 
 having been converted either into iron shale or rust, which rust was 
 probably blown away almost as fast as it formed by the violent sand 
 carrying winds of the region, wherever such meteorites were exposed 
 to their action. You will note that the map shows that a discovery 
 
 10 
 
was made some time ago, nearly five miles from the crater, of a 
 number of pieces of iron shale and a number of ordinary very small 
 Canyon Diablo siderites grouped together. This means that a shale 
 ball meteorite of probably considerable size fell on this spot and that 
 the shale and the iron, as represented on the map, are all that remains 
 of it. This peculiar association of the two, iron shale and small iron 
 meteorites, is too marked here and in other instances to admit of any 
 other explanation. 
 
 I am willing to admit that the finding of many, and especially the 
 great pieces of ordinary Canyon Diablo meteoric iron, weighing fre- 
 quently over 300 and in one specimen over 1000 pounds, which are 
 not now surrounded by any iron shale, does not seem to be in agree- 
 ment with this theory. Again, one of these large iron meteorites, 
 with no shale surrounding it, was found slightly embedded, but with 
 a point protruding, in the silica and rock fragments on the northeast 
 slope of the mountain, and almost immediately beneath it within a 
 few feet, there was found a large shale ball meteorite with a solid 
 iron center. It is certain that neither had been moved appreciably 
 since they came to rest in the silica and ejected rock fragments. 
 Possibly these large, deeply pitted, and many of the small meteorites, 
 both of which we know as ordinary Canyon Diablo siderites, were 
 individual meteorites trailing behind the cluster. It has been suggested 
 that they are fragments due to the bursting in the atmosphere of 
 a larger mass. Their shape, however, does not indicate this. It 
 has also been suggested that they were hurled out of the crater 
 at the time of the impact, but this seems to me improbable. The 
 characteristic pittings of the large Canyon Diablo siderites strongly 
 suggest the idea that these cavities were once filled with globular 
 masses of shale ball iron, which have disintegrated upon exposure to 
 the action of the earth's atmosphere. But we have no proof of this. 
 I am also willing to admit that a few very large irregular masses of 
 iron shale, as shown on the map, have been found which by their 
 present shape would indicate that the iron meteorite, from which 
 they are certainly derived, may not have been as globular as the vast 
 majority of the shale balls which we have found. We have not yet 
 found any characteristic Canyon Diablo siderites among the remains 
 of the shale balls which have disintegrated since they have been in 
 our possession. Nor have we found them in any of the disintegrated 
 shale balls which have oxidized in situ in the silica on the outer slopes 
 of the mountain. Notwithstanding these facts, the evidence is quite 
 strongly confirmatory of the theory that many of the smaller, and 
 especially the very small. Canyon Diablo siderites have been derived 
 from the disintegration of shale ball meteorites great and small. 
 There is a characteristic shape among many of them which points 
 to a common origin and is opposed to the theory that they are frag- 
 ments due to the rending of a large mass of iron; at least after it 
 entered the earth's atmosphere. Less than a dozen specimens, vary- 
 ing from a few grains or ounces to several pounds in weight, have 
 been found, however, in which there are small cracks suggestive of 
 the fact that the iron has been subjected to a certain amount of strain 
 and rending. These cracks are so small and have been so seldom 
 observed that I do not think importance should be attached to them 
 in this connection. 
 A conclusion which we can deduce from these facts and those 
 
 II 
 
which will be hereafter stated, is that the crater was not made by a 
 single giant meteorite, but rather by a compact cluster or swarm of 
 many thousands of shale ball meteorites and also possibly of other 
 iron meteorites, as explained above, traveling together as the head, or 
 part of the head, of a small comet. Those which fell outside of the 
 crater, on this theory, were probably stripped off from the cluster in 
 its passage through the atmosphere, or perhaps they had been trailing 
 behind it in space, or had been traveling with it concentrically sur- 
 rounding it, yet separated from it by considerable distances. They 
 would, of course, have been much more retarded by the resistance 
 of the earth's atmosphere than the main mass or central cluster, and 
 would have reached the earth after it did, possibly while it was 
 forming the crater. The concentric distribution of the many thou- 
 sand pieces of shale (certainly derived from shale ball meteorites) 
 around the crater for a distance of five and one-half miles, is in 
 accord with this theory. I do not think it is probable that the 
 majority, if any, of these globular masses of nickel iron were 
 thrown out of the crater at the time of the impact. They in no 
 wise resemble angular fragments torn from a solid mass. Again, 
 many small ones have been found twice as far from the crater as 
 any of the ejected rock fragments have been found. The evidence 
 to my mind is in favor of the large majority of them having fallen out 
 of the sky upon the plain or upon the crater rim at or near the 
 places where they or their remains have been found. The iron 
 centers, when sawed in two and etched, show the Widmanstatten 
 figures beautifully, as do the ordinary Canyon. Diablo siderites 
 wherever found, and this, I am told by those who have made 
 the experiment, they would not do if they had been heated 
 beyond 700 degrees or 800 degrees Centigrade. If they were hurled 
 out of the crater by the force of the impact with sufficient violence 
 to have been thrown a number of miles, it would seem that they 
 would have been more highly heated than this. And this appears all 
 the more reasonable when one remembers the evidence of high tem- 
 perature in the rocks immediately adjacent to the advancing projectile, 
 for it would seem that the projectile would have been as highly 
 heated, especially in its outer portions, and these, it would seem, are 
 the very portions which would have been hurled out of the crater by 
 the force of the impact, if any portions of it were expelled. On the 
 other hand, if shale ball meteorites were stripped off the outside of 
 the cluster in the upper atmosphere they would have been retarded 
 in their subsequent passage through it and would have reached the 
 earth a fraction of a second, or a few seconds perhaps, later than the 
 main body or cluster, and possibly, as suggested above, while the 
 fragments of rock were pouring out of the crater or settling on the 
 outer slopes of the rim. On this theory they would not have been 
 very hot when they fell upon the earth. It is easily conceivable that 
 because of air resistance they might not only have been retarded, but 
 might have taken a slightly divergent course from that of the main 
 body. It is also easily conceivable that members of the swarm were 
 trailing some distance behind the main cluster, or perhaps were sur- 
 rounding it in space. But even admitting that some of them were 
 thrown out at the time of the impact, for example those embedded 
 in the silica and rock fragments on the crater rim, it is only another 
 
 12 
 
argument in favor of the crater having been made by a dense cluster 
 of shale ball and possibly other iron meteorites. 
 
 If the crater was made by a single giant iron meteorite it is very 
 hard for me to realize, remembering the toughness of this nickel 
 iron, and remembering the fact which Professor Magie was the 
 first to point out to me, that the temperature of such a meteorite 
 traveling in space would not be very low, how it should have broken 
 up into a great number of very small pieces. If it did not break 
 up in this manner the dip needle should indicate its presence in the 
 depths of the crater. It is clear, as we shall see, that there is not 
 nearly sufficient evidence of heat inside or outside of the crater to 
 warrant the conclusion that it went into the form of vapor or of fine 
 metallic mist when it struck. The absence of staining by iron and 
 nickel oxides on a grand scale is absolutely opposed to such a theory. 
 It should be stated also that there is not the slightest evidence, either 
 inside or outside of the crater, to warrant the conclusion that the pro- 
 jectile was composed of anything but nickel iron ; unless the finding by 
 me of a single small aerolite about one and one-half miles N. W. of 
 the crater, several years ago, may be regarded as such. As stated 
 in my former paper, there is fairly good reason to believe that this 
 aerolite was seen to fall in the winter of 1904-5.* It is recognized, 
 however, that it may have been a member of the swarm, the central 
 or probably the most advanced portion of which, when it struck the 
 earth, was the projectile which made the crater, and which, from all 
 the evidence, was almost wholly composed of iron meteorites. From 
 this point of view the finding of an aerolite lends support to the 
 theory that the crater was made by a compact cluster of meteorites. 
 No other aerolite and no piece of meteoric stone has been found in 
 the crater or in the vicinity of it. Surely in all our exploration and 
 constant search during six years we would have found some addi- 
 tional evidence of the fact had the crater been made by the impact 
 of a stony meteorite or a cluster formed in large part of stony meteor- 
 ites. We have searched very diligently for such evidence, both inside 
 and outside of the crater. If it was in part a stony meteorite or 
 a cluster composed" largely of stony meteorites, it seems certain that 
 we would have found some small pieces of meteoric stony material 
 in the shafts, in the drill holes, or attached to the many thousands of 
 pieces of nickel iron or nickel iron oxide which we have found. The 
 finding of the remains of shale balls in the talus on the inside slopes 
 of the crater, as described below, furnishes additional support to the 
 theory that the crater was made by the impact of a compact cluster 
 of meteorites. 
 
 Professor Magie checked during the past summer the observations 
 of Mr. Marcus Baker, of the United States Coast and Geodetic Sur- 
 vey, which were made in behalf of the United States Geological 
 Survey, when the latter made an examination of the crater in 1891. 
 Like Mr. Baker, Professor Magie finds no systematic variations of the 
 magnetic declination or the magnetic dip in different parts of the floor 
 of the crater, such as one would expect if there were a large mass 
 of iron buried beneath it; I mean a mass of the size which was 
 
 *Coon Mountain and Its Crater, Proceedings of the Academy of 
 Natural Sciences of Philadelphia, December, ipo^, pp. 883-884; 
 American Journal of Science, Vol. XXI, May, ipo6, pp. 347-355. 
 
 13 
 
Missing Page 
 
Missing Page 
 
Proved simultaneity in time between the formation of the crater and 
 the deposition of the rneteoric material found on the surrounding 
 plain, and especially among the ejected rock fragments. (No. 5.) The 
 formation of Variety A of the metamorphosed sandstone in 
 various degrees of metamorphism, with its slaty structure 
 showing great lateral pressure, or pressure radiating from the 
 advancing projectile; also the formation of Variety B of the 
 metamorphosed sandstone; and as part of these facts evidence of 
 just such fusion of the sandstone as would have taken place under the 
 influence of a sudden and very great, but not long continued, rise of 
 temperature, which could not have taken place, it is safely assumed, 
 if there had been such a great single steam explosion as has been 
 advanced to account for this crater. (No. 6.) The fact that the 
 ejected rock fragments were deposited, generally speaking, in the 
 reverse order in which they occur stratigraphically. (No. 7.) The 
 forniation of, and especially the distribution of, vast quantities of 
 silica or rock flour on the outer slopes of the rim of the crater and 
 in the depths of the crater itself. (No. 8.) The roundness of the 
 crater, especially when studied in connection with the remarkable 
 symmetry exhibited inside and outside; that is to say, by 
 the dip of the strata, by the two fields of big boulders (angular 
 limestone fragments) which were thrown out to the east and west, 
 by the fact that a much greater amount of ejected material was 
 thrown to the south than elsewhere, by the fact that this material is 
 more commijiuted than elsewhere ; all of which facts, when con- 
 sidered together, are suggestive of impact and would be impossible 
 under the steam explosion theory. (No. 9.) The vertical bodily 
 .uplifting of the strata, form.ing a portion of the southern wall for 
 one-half mile in length, with the turning backward of the same strata 
 on either side, in a way which not only, as I think, precludes 
 the possibility of the effect having been produced by a steam ex- 
 plosion, but which suggests that it was produced by something having 
 been driven underneath like a wedge. (No. 10.) The fact that the 
 crater is situated in almost the exact center of an area on which 
 more iron meteorites have been found than on all of the rest of the 
 surface of the earth, added to the fact, as stated above, that it is 
 proved that these iron meteorites fell at the same time that the 
 crater was made. (No. 11.) The finding of undoubted meteoric 
 material not only deeply embedded in the talus at the base of the 
 limestone cliffs and underneath the lacustrine deposits, but also, 
 which is conclusive, five and six hundred feet below the floor of the 
 crater in association with the two varieties of the metamorphosed 
 sandstone and with the other fragmentary material which fills the 
 lower portion of the crater. 
 
 These are the principal arguments which occur to me at present, 
 but there are many others which, as I think, render the steam explo- 
 sion theory or any other theory based upon manifestation of volcanic 
 activity absolutely untenable. We are therefore forced back to the 
 theory of irtipact, against which in all of the diligent exploration, 
 which has been extended over a period of six years, we have not 
 found a single fact great or small. 
 
 The only argument worth considering against the meteoric 
 hypothesis is that there are no systematic variations of the magnetic 
 
 16 
 
declination, or of the magnetic dip, in or around the crater. From 
 such experiments as we have been able to make it is believed that 
 there might be many thousands of shale ball or other iron meteorites 
 in the bottom of the crater, the combined magnetic field of which 
 would not effect the dip needle at a distance of 500 or 600 feet. (In 
 this connection note the experiment described under the final heading, 
 "What has become of the projectile?"). The shale ball iron and also 
 iron oxide, as I understand, both show intrinsic magnetization; from 
 which it is argued that the irregularly distributed masses in the bottom 
 of the crater would neutralize each other's fields. Besides, the prob- 
 ability is that the magnetic lines of force of the mass where it 
 probably lies would not deviate much from the earth's lines. 
 
 Since the facts are as I have stated them to be it would seem 
 to me that it is idle to further discuss the origin of the crater. It 
 is proved from this overwhelming array of facts that some extra 
 terrestrial body — supposedly a giant iron meteorite composed of both 
 kinds of iron which I have described, or as now see.ms much more 
 probable, a dense swarm or cluster of iron meteorites composed of 
 shale balls and perhaps also of ordinary Canyon Diablo siderites — 
 entered the crater. The discussion, therefore, should henceforth be 
 narrowed down to what was the nature of this mighty projectile and 
 what has become of it, which is by far the most interesting visitor 
 or group of visitors from outer space of which we have any record. 
 So far we are utterly unable to account for such a mass of nickel iron 
 as could have made this great hole in the rocky surface of the earth, 
 a mass which, as has been very roughly estimated, probably weighed 
 in excess of a million tons. It would seem that it must have been 
 several hundred feet in diameter; for conservatism let us say three 
 hundred feet. A very few thousand tons is all that we are able so 
 far to account for on any reasonable hypothesis, both inside and out- 
 side of the crater, and most of this, as we shall see, can probably be 
 excluded from the calculation. This is not enough. Where is the 
 other ninety-nine per cent, plus? 
 
 WHAT HAS BECOME OE THE PROJECTILE? 
 
 The following facts and conclusions are given at the risk of repeti- 
 tion, so that the argument may be easily followed : 
 
 Since we can dismiss as unworthy of discussion, if not impossible, 
 the theory that the whole mass of the projectile after striking the 
 earth rebounded into space, or rebounded so high that when it again 
 fell upon the earth it sank, for example, beneath the waters of the 
 Pacific Ocean (for it is nowhere on the treeless rocky plain which 
 surrounds the crater for many miles), it seems to me that the discus- 
 sion is narrowed down to 
 
 (A) Was the projectile broken into many small pieces and thrown 
 out of the crater after having penetrated, as has been proved, between 
 1 100 and 1200 feet of rock? 
 
 (B) Has it disappeared in the crater through oxidation or from 
 any other cause? 
 
 (C) Is it still somewhere and in some form in the depths of the 
 crater ? 
 
 We shall take up first the consideration of A, which is, in effect, 
 are all the pieces of nickel iron or nickel iron oxide, shale ball or 
 
 17 
 
otherwise, which WP Jind distribjited around the cratentoraii;&xtr^"e 
 distance of approximately^ five ^aiad one-half miles from it, f ragi^ei^s 
 of the mass which made the cfater ? It seems to me now that this 
 must be answered in the negative, for we know or have strong reason 
 to believe 
 
 1. That all of the nickel iron shale which we find distributed about 
 the crater to the extreme distance mentioned is due to the terrestrial 
 oxidation of shale balls. 
 
 2. That the original shape of the great majority, if not of all, of 
 these shale balls was roughly globular, rounded, pear, almond or egg 
 shape, often, as among the specimens now converted into hard dense 
 iron shale, very distinctly pointed at one end. 
 
 3. That they are therefore not fragments of anything, but that 
 most of them, if not all, were separate individuals when they fell. 
 This we know not only from finding more than a hundred shale balls 
 at considerable distances one from the other in the upper portion of 
 the silica and rock fragments on the outer slopes of the crater rim, 
 but also from the frequently observed grouping of many slightly 
 curved pieces of iron shale of characteristic shape far out on the 
 plain and removed from any other iron shale by hundreds of yards, 
 which is indicative of the fact that a shale ball fell and disintegrated 
 at this spot. 
 
 4. That the iron centers of these shale balls upon section show in 
 all cases the Widmanstatten figures, and also that the Canyon Diablo 
 siderites, great and- small, also always show somewhat different 
 Widmanstatten figures when cut and etched. 
 
 5. That they could not show these figures upon section if these 
 pieces of meteoric iron had ever been heated beyond 800 degrees 
 Centigrade. If they were fragments hurled out of the crater, many 
 to~ great distances, at the time of the impact because of the splitting 
 up of the projectile, if seems certain that not only would their shape 
 be angular and "otherwise indicative of the fact, but it is also reason- 
 ably certain that many of such fragmetits would have been white 
 hot when they left the crater. It has been suggested that they may 
 have been drops of' liquid molten iron. This is clearly impossible 
 for a number of reasons. For example, such drops could not have 
 held together for considerable distances. In this connection it should 
 be remembered that the remains of some of the shale balls have been 
 
 , found approximately five and one-half miles distant from the crater, 
 much further than any of the ejected rock fragments. Also that 
 some of the very small shale balls, now converted into hard, dense iron 
 shale, have been found several miles from the crater. Therefore, 
 as has been pointed out, it is practically certain that these were not 
 
 ^ ejected from the crater. The distance, in all probability, is too great. 
 The fact that the large' spurts or jets of white sandstone fragments 
 
 ' are confined, practically speaking, to the northeast one-third of the 
 crater rim, and the further fact that most of the shale balls which 
 we have so far found' embedded in the silica and rock fragments, 
 have been found, so to speak, between these spurts; strongly siigge^t, 
 as I 'am willing to admit, that som^ of the shale balls were throwri out 
 of the crater at the time when the jets or spurts of white sandstone 
 were 'squeezed olit of it.' (See Appendix.) It should also be re- 
 
 " liiembered that it is certain that the shale balls do riot owe their 
 
present globular shape to weathering in situ in the silica or in the 
 soil on the outside plain. Any one who has dug them out of the 
 almost snow white silica and observed the very small amount of 
 concentric staining by which they are surrounded, does not need to 
 be further convinced of this fact. The oxidation of the iron having 
 proceeded equally fast from the outside inwardly, the present shape 
 of the iron center is also conclusive proof that the original shape 
 of the complete meteorite was not very dissimilar. From all of 
 these facts and arguments it is highly probable, if not proved, that 
 most of the so-called shale ball meteorites so far found fell out of 
 the sky independently of the main mass or cluster, and as separate 
 individuals struck the earth at or within a few feet of the places 
 where we now find them or their remains, and therefore had nothing 
 whatever to do with the formation of the crater. 
 
 6. That a large majority of the ordinary Canyon Diablo siderites 
 are, in all probability, merely residuals from the decomposition of 
 the shale balls. (N. B. — It will be noted that I say the large 
 majority, for I cannot yet bring myself to believe that all of the 
 Canyon Diablo siderites were once parts of shale balls.) 
 
 7. Even supposing that the amount of nickel iron or nickel iron 
 oxide which has been found concentrically distributed on the plain 
 round about the crater (not to exceed 10 tons, which is an outside esti- 
 mate) represents only about one-half of one per cent, of the amount 
 or iron which was so distributed immediately after the impact, and 
 supposing that it was all part of the projectile which made the crater, 
 we would have something like two thousand tons as the total weight 
 of the projectile. This is on the supposition, in my opinion clearly 
 erroneous, that all of the projectile was hurled out after the impact 
 except that now represented by the finely divided nickel and iron 
 oxide which we have found in the depths of the crater. Even when 
 this is added there would be represented a mass which is absurdly 
 small when the great size of the crater (three-quarters of a mile in 
 diameter) and the enormous amount of energy which has been ex- 
 pended is remembered. In short, even if we double or treble the 
 weight of all the meteoric iron which we can reasonably assume to 
 have existed a moment after the impact, either outside or inside of the 
 crater, from all the masses and particles of iron or of iron oxide 
 which we have found, it is not conceivable, in view of the facts pre- 
 sented, that a meteorite or cluster of meteorites of such relatively 
 small weight could have done the work. 
 
 By exclusion this brings us to the consideration of B, that is to 
 say, has the meteoric material of which the projectile was formed 
 oxidized in the bottom of the crater since the fall, and to all intents 
 and purposes disappeared, having been carried oflf by percolating 
 waters, or has it practically disappeared through any other agency? 
 This also must be answered in the negative, since 
 
 I. All of the oxidized meteoric material which we have so far found 
 in the depths of the crater by means of the drill — in the aggregate 
 representing at the most, in my opinion, only a few hundred tons of 
 nickel iron — is in an exceedingly fine state of subdivision, and is 
 known to have been plastered on, as if it had been thrown against. 
 Variety B, and is often found in connection with Variety A of the 
 metamorphosed sandstone, as well as in the silica. Many of these 
 
 19 
 
particles of meteoric iron oxide are so small as to be seen with 
 difficulty by the unassisted eye. Some of the larger of these parti- 
 cles are shown to contain what appear to be metallic cores, or it 
 may be schreibersite, when rubbed in an agate mortar. (The oxide 
 or iron shale forming part of shale balls found on the outside of the 
 crater frequently show thin bright streaks or small masses of what 
 I have been informed is schreibersite.) This does not indicate 
 complete oxidation even of such minute particles. In this con- 
 nection it is not improper to point out that if the mass struck hard 
 enough to split up into these minute particles, it would have 
 split up in this way, in all probability, at the instant it struck, and 
 long before it penetrated some iioo to 1200 feet of solid rock. It 
 is certain that the bits of metal represented by these particles, which 
 are now either in the form of nickel iron oxide or nickel iron silicate, 
 and which vary from mustard seed to pin heads in size, though 
 occasionally somewhat larger, could not in themselves do much in the 
 way of penetrating rock. (It is of course recognized that their brit- 
 tleness and the grinding action of the drill when it detached them 
 from the metamorphosed sandstone, to which in some cases they 
 were doubtless adhering, have contributed to their apparent smallness 
 in size.) It is perfectly safe to assume that the small mass of nickel 
 iron, which would be represented by the aggregate weight of all of 
 these minute particles of nickel iron oxide, could not have made 
 such a crater, even if it had been moving at the highest speed meteor- 
 ites are known to have in space and irrespective of the retardation, 
 whatever it may have been, of the earth's atmosphere. The smaller 
 the mass the greater the retardation. And in this connection it must 
 not be forgotten that if the mass struck at such very high speed it 
 could not, in my opinion, have penetrated to the proved depth of 
 over 1 100 feet, because the energy would have been largely expended 
 in the deformation of the projectile. If it had been traveling at such 
 speed we would have had, besides a very shallow crater, abundant evi- 
 dences of fusion of the rocks and volatilization of the projectile. 
 Conversely, the fact that the projectile was not volatj^ed and the 
 fact that we know that it penetrated over 11 00 feet through solid 
 rock, furnish, as it seems to me, quite strong proof that the mass, 
 when it struck and began to penetrate the horizontal strata, was not 
 moving at a very high speed, considering the speed at which bodies 
 in space are known to travel; also that the weight of the mass was 
 very great.* 
 
 2d. We do not find enough evidence of heat or of staining to 
 justify us in the behef that all of the great metallic projectile, what- 
 ever its form, went at any time into this state of subdivision. 
 
 3d. The evidence also is all against its having gone into a state 
 of vapor at the moment of impact. In this connection it is only 
 necessary to again point out that the absence of staining on a grand 
 scale, in the depths of the crater and outside, is practically conclusive 
 proof that the projectile did not either go into the form of vapor or 
 of metallic mist upon impact, for a small amount of such metallic 
 vapor or mist, so to speak, would have caused an immense amount 
 
 *In this connection, however, and in connection with the third 
 argument below, see the recent interesting remark of Professor 
 H. N. Russell, zvhich is given in the Appendix at the end of this paper. 
 
 20 
 
of staining of the rock fragments and silica. If this negative pf&of 
 is not sufficient the absence of evidences of fusion of the rocks on a 
 grand scale coupled with it, would seem to be conclusive that the 
 projectile was not vaporized and did not go into the form of metallic 
 mist. It is argued with force, on the other hand, that something very 
 solid and incompressible penetrated deeply into the white or gray 
 sandstone, hundreds of feet below the original level of the plain 
 where it struck. It is necessary only to remember in this connection 
 the peculiar slaty cleavage so frequently shown by Variety A of the 
 metamorphosed sandstone. How can this be explained otherwise? 
 
 4th. The body of unstained and almost snow white silica immedi- 
 ately underneath the horizon where we find most of the finely divided 
 but undoubted meteoric material, precludes the possibility of any large 
 mass of iron having oxidized in this horizon, at least where we have 
 explored it. The amount of iron and nickel oxide which has been 
 found in the central area of the crater prospected by the drill has been, 
 after all, as pointed out, only in the aggregate probably less than a 
 thousand tons ; certainly not enough, especially when reduced back 
 to a metallic condition, to account for more than an exceedingly small 
 fraction of such a mass as was required to make the crater, even 
 assuming high speed. This much might easily have been thrown 
 off as sparks (some of it, as has been proved, being vaporized") from 
 a very large projectile or a large, compact cluster of shale balls and 
 other meteorites while penetrating some twelve hundred feet of rock. 
 
 By further exclusion we are now brought to the consideration of 
 C, that is, is the mass which made the crater still in it at some 
 undiscovered place and in some form? In my opinion, this question 
 must be answered affirmatively. 
 
 The only argument which now seems to be worthy of serious 
 consideration against this conclusion is that the magnetic dip needle 
 has not shown, in two carefully made surveys within the crater and 
 immediately outside of it, any variation from the usual dip in this 
 region ; that is to say, anywhere within a ten or twenty-mile radius 
 of tne crater. As against this theory we know that a box half full of 
 shale balls and ordinary Canyon Diablo siderites weighing in all 
 nearly 200 pounds, was brought directly under the dip needle in an 
 excellent instrument, in fact, between the legs of the tripod on which 
 the instrument was mounted and within three feet of the instrument 
 itself, and yet no movement of the needle was noticed. It would 
 seem justifiable, therefore, to conclude that a vast number of similar 
 masses of meteoric iron may be hidden in the depths of the crater, five 
 to seven hundred feet below the surface, without the needle in the 
 instrument showing any variation of dip because of their presence. 
 
 We are thus compelled to conclude that the mass which maae the 
 crater, and which, as has been suggested above, may have been the 
 metallic head of a small comet, lies in the bottom of it somewhere; 
 for if it was a compact cluster of iron meteorites which made the 
 crater — there is certainly a great deal of evidence in favor of this 
 theory and none against it — it would seem from the evidence most 
 unlikely that any considerable portion was expelled after the cluster 
 had penetrated some iioo to 1200 feet of limestone and sandstone 
 strata. When the metallic mass is found, it would seem probable 
 that it will be found to have partially oxidized, much after 
 
 21 
 
the manner of the buried shale balls, in which event it would 
 still possess great commercial value. As yet we do not know 
 where it is in the large area covered by the crater, but I personally 
 think it probable that, in the form of a vast number of shale balls 
 and perhaps Canyon Diablo siderites lying more or less closely to- 
 gether, most of it will be found far over in the southern or south- 
 eastern portion of the crater, where no prospecting by the drill has 
 been done, and that some of it, if not the larger part of it, will be 
 found underneath the perpendicular cliffs which form the southern 
 wall. 
 
 APPENDIX. 
 
 Since the above paper was read Professor H. N. Russell has made 
 a suggestion to the author which interests him greatly, and on the 
 theory, which now seems so plausible, that the mass which made the 
 crater was composed of many thousands of shale balls and ordinary 
 Canyon Diablo iron meteorites, explains quite satisfactorily many of 
 the facts which he has endeavored to describe. Briefly it is this. 
 The meteoric mass, in passing through the atmosphere, would neces- 
 sarily push before it a great mass of compressed and highly heated 
 air. There would be no time for this air to escape sidewise to any 
 great extent. A mass of the great size (perhaps several hundred 
 feet in diameter) necessary to account for all the phenomena ob- 
 served, moving at 15 to 30 miles per second — which is the sort of 
 velocity to be expected — would cut out a "wad" of air going through 
 the atmosphere like a charge of shot going through a board in front 
 of the muzzle of a shotgun. The total mass of this entrained air 
 might be as great as that of the original meteorites. In this way 
 the blow at the earth's surface would be to a certain degree cushioned, 
 which would help to account for the absence of notable evidences of 
 volatilization of the iron. The mass of hot air would be fairly driven 
 into the sandstone and limestone strata by the first impact, and. would 
 then escape upward around the advancing projectile and be very 
 efficient in removing the pulverized and shattered rock, and so in 
 digging the crater. 
 
 This cushion of air, as it seems to me, would not only explain why 
 the shale ball and ordinary Canyon Diablo iron meteorites were not 
 deformed or broken by the impact, but, on the theory that the cluster 
 held together, shedding, perhaps, a number of meteorites as it passed 
 through the atmosphere, might explain the distribution of part of the 
 small proportion of the mass, or the remnants thereof, which has been 
 found outside of the crater and immediately surrounding it. That 
 is to say, when the cushion of compressed air struck, the rock imme- 
 diately in front of it was ground to impalpable powder. The en^ 
 trained air then began to escape with great force around the sides 
 of the mass and carried backward with it not only all the first made 
 pulverized rock, but, during the later stages of the process, stripped 
 off some of the meteorites from the outer portions of the cluster, and 
 distributed them through the ejected material. I still think it prob- 
 able, however, that many, if not most, of the meteorites found in the 
 uppermost layers of the debris, and all of those found on the open 
 plain, fell directly from the sky, as stragglers following the main mass. 
 
 22 
 
The less violent escape later of some remaining portion of this 
 compressed air imprisoned in front of the projectile, as it advanced 
 through the white or gray sandstone, hundreds of feet below the 
 surface of the plain, may also account for the remarkable spurts or 
 jets of white or gray sandstone fragments on the northeast one- 
 third of the rim, and for the relatively large number of shale balls 
 found embedded in the upper portion of the silica on its outer 
 slopes between these spurts of sandstone. The highly heated mass 
 of compressed air may also be largely responsible for the formation 
 and distribution of Variety A and Variety B of the metamorphosed 
 s'andstone and of the bluish opalescent quartz. 
 
 If this additional theory is correct— it will be noticed that it is not 
 opposed to any of the principal theories advanced in the above paper 
 to account for the creation of the crater and the attendant phenomena, 
 ■ — then it, practically speaking, proves several things. First, that the 
 crater was made by a great cluster of iron meteorites, weighing in 
 ail likelihood not less than a million tons, for the cluster must have 
 had very considerable superficial area or opposing surface. Second, 
 that if the shale ball and other iron meteorites stripped off the cluster 
 while it was penetrating the strata and carried backward out of the 
 crater, especially those which were thrown out last, were saved from 
 being volatilized by the cushion of compressed air, practically all the 
 rest of the cluster which remained in the crater was likewise saved 
 from such a fate. Third, that we have a very fair sample of the com- 
 position and general characteristics of the individuals composing the 
 cluster in those torn off from its outer portions. Fourth, that prob- 
 ably upwards of ninety per cent, of the mass lies in the bottom of 
 the crater or beneath the cliffs which form its walls. The mass of 
 compressed air having escaped from in front of the projectile, it is 
 conceivable that there would have been an opportunity for the indi- 
 vidual meteorites, composing that portion of the cluster which re- 
 mained in the crater, to separate to a limited extent in the space dug 
 by the compressed air ahead of the cluster while the flying rock frag- 
 ments were still in the air and before some of them settled back into 
 the crater and filled its lower portion. 
 
 Note. — There are three collections of specimens which include 
 everything from Meteor Crater to which reference has been made in 
 this paper; one at the Guyot Laboratory of Princeton University, 
 Princeton, M. /.; one at the U. S. National Museum, Washington, D. 
 ' C, and one at the Crater itself in Coconino County, Arizona. If it is 
 possible, these specimens should be studied by those who are inter- 
 ested in the subject. Such a study cannot fail to be of assistance 
 in enabling them to understand the arguments set forth in this paper. 
 But it is of far more importance that they should visit the Crater 
 itself, for not until one does so can he appreciate fully all that this 
 and other papers on the subject have attempted to describe. 
 
 A number of the photographs which illustrate this paper have been 
 taken by Prof. Gilbert Van Ingen, of the Geological Department of 
 Princeton University. His work in this connection is gratefully 
 acknowledged. 
 
 23 
 
BIBLIOGRAPHY. 
 The following references to papers on Meteor Crater are given, 
 in the order of the dates of their publication : 
 
 A. E. Foote, in Amer. Jour, of Sci., vol. 42, p. 413, 1891; also 
 in Proc. Am. Assoc. Adv. Sci., vol. 40, pp. 279-283, 1892. 
 
 G. K. Gilbert, 13th Ann. Rept. U. S. Geological Survey, part i, 
 p. 98, 1892; 14th Ann. Rept., part i, p. 187, 1893; Geological Society 
 of Washington, Presidential Address, March, 1896; Science (new 
 series), vol. 3, pp. 1-13, 1896. 
 
 O. A. Derby, Constituents of the Canyon Diablo Meteorite, 
 Amer. Jour, of Sci., Vol. 49, February, 1895, pp. loi-iio. 
 
 Brezina, Cohen and Huntington have also written on the Canyon 
 Diablo irons. 
 
 Chamberlin and Salisbury's Geology (1904), vol. i, p. 569. 
 D. M. Barringer and B. C. Tilghman, First mention of the dis- 
 covery that the crater is an impact crater and not a crater produced 
 by a steam explosion. President's statement, Proceedings of Acad. 
 Nat. Sci., Philadelphia, December 5, 1905. 
 
 D. M. Barringer, Coon Mountain and its Crater. Proc. Acad. Nat. 
 Sci., Philadelphia, December, 1905, pp. 861-886. (Issued March i, 
 1906.) 
 B. C. Tilghman, Coon Butte, Arizona. Ibid., pp. 887-914. 
 J. W. Mallet, Amer. Jour, of Sci., vol. 21, May, 1906, pp. 347-355. 
 J. C. Branner presented the papers of Messrs. Barringer and Tilgh- 
 man before Section E, Amer. Assn. Adv. Sci., at the Ithaca meeting, 
 June 29, 1906, with the results of his own study of the phenomena, 
 which favored the view of meteoric origin of the crater. Science, 
 vol. 24, September 21, 1906, pp. 370-371. 
 
 H. L. Fairchild, at Tenth Session of the International Geological 
 Congress, in Mexico, September 14, 1906, presented the new facts 
 favoring the impact origin of the crater, and exhibited the various 
 materials. The record will be found in Compte Rendu, X Session, 
 Congress Geol. Inter., Mexico, 1906, p. 147. 
 
 O. C. Farrington, Analysis of siderite oxides or "iron shale" and 
 discussion of its origin and relation to the typical Canyon Diablo 
 irons in Amer. Jour, of Sci., vol. 22, October, 1906, pp. 303-309. 
 
 G. P. Merrill, On a peculiar form of metamorphism in silicious 
 sandstone. Proc. U. S. Nat. Museum, vol. XXXII, pp. 547-550, 
 June 15, 1907. 
 
 G. P. Merrill and Wirt Tassin, Contributions to the study of the 
 Canyon Diablo meteorites, Smithsonian Miscl. Collections (Quarterly 
 Issue), vol. 50, part 2, pp. 203-215 ; pis. 8-21, September 12, 1907. 
 
 H. L. Fairchild, Origin of Meteor Crater (Coon Butte), Arizona 
 Bulletin of the Geol. Soc. of Amer., vol. 18, pp. 493-504, pis. 54.56, 
 December, 1907. 
 
 G. P. Merrill, The Meteor Crater of Canyon Diablo, Arizona; its 
 history, origin, and associated meteoric irons, Smithsonian Miscl 
 Collections (Quarterly Issue), vol. 50, part 4, pp. 461-498; pis. 61-75, 
 January 27, 1908. 
 
 24 
 
Later Papers 
 
 W. F. Magie, Physical Notes on Meteor Crater, Arizona. Pro- 
 ceedings of the American Philosophical Society, vol. XLIX, No. 194, 
 1910. 
 
 Elihu Thomson, The Fall of a Meteorite. Proceedings American 
 Academy of Arts and Sciences, vol. XLVII, No. 19, March, 1912. 
 
 Elihu Thomson, A Hunt for a Greater Meteor. Scientific Ameri- 
 can, Supplement No. 1896, May 4, 1912. 
 
 Daniel Moreau Barringer, Further Notes on Meteor Crater, 
 Arizona. Proceedings of the Academy of Natural Sciences of Phila- 
 delphia, September, 1914. 
 
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 ONE OF THE FURTHEST THROWN LARGE FRAGMENTS OF LIMESTONE. 
 
 -■^-4>V 
 
 
 MONUMENT ROCK NEAR RIM IN EASTERN FIELD OF BIG BOULDERS 
 
 PLATE VI 
 
ONE OF THE VERY LARGE HALF-BURIED FRAGMENTS OF LIMESTONE ON WESTERN SLOPE. 
 
 CHARACTERISTIC VIEW OF CRATER RIM SHOWING PLAIN IN THE DISTANCE. 
 
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 BARRINGER POINT- H IGHEST POINT ON CRATER RIM. 
 
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CHARACTERISTIC VIEW OF RIM--SHOWING TILTED STRATA, 
 
 ANOTHER VIEW OF THE RIM WITH PLAIN IN THE DISTANCE. 
 
 ANOTHER VIEW OF THE RIM SHOWING OUTCROP OF SLIGHTLY TILTED UPPER RED SANDSTONE 
 
 AND OF THE LIMESTONE UNDERNEATH. 
 
 PLATE VIII 
 

 ONE OF THE FURTHEST THROWN LARGE FRAGMENTS OF LIM ESTON E- SOUTH WEST SLOPE. 
 
 VIEW ON SOUTHERN RIM CEDAR FOREST ON PLAIN AND SUNSET MOUNTAIN IN DISTANCE. 
 
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UPPER FOUR SPECIMENS ARE TYPICAL PIECES OF VARIETY " B." 
 
 Specimen on left abundantly stained and specked by nickelnron oxide. The stain is supposed to represent the effect of 
 flame and the dark-colored specks the effect of sparks or minute bits of burning metal. The lowest specimen is a fine example 
 ■of the bluish, opalescent quartz surrounding variety " B," and representing complete fusion of the silica. 
 
 TYPICAL METEORIC MATERIAL FROM DEPTHS OF CRATER BROUGHT UP BY THE DRILL. 
 The black specks represent nickel-iron oxide and nickeHron silicate: the white specks small fragments of variety "A" 
 and variety --B." The trained eye with the aid of a glass will detect a few pieces of the bluish, opalescent' quartz 
 Meteoric material more or less concentrated. Natural size. 
 
 SAME AS ABOVE. 
 
 It must be understood that meteoric material has rarely been found in the depths of the crater as abundantly 
 mixed with the surrounding material as shown in these photographs. Natural size. 
 
 PLATE XIV 
 
SHALE BALL METEORITES WITH NICKEL-IRON CENTERS AS THEY APPEAR WHEN DUG OUT OF THE SILICA. 
 One iron center (on the right) is disclosed, the others are still covered by a heavy coating of nickel-iron oxide, 
 
 jreatly reduced. 
 
 or so-called iron shale. 
 
 TYPICAL SHALE BALLS WITH NICKEL-IRON CENTERS. 
 
 Note the Widmaiistatten figures shown on the two specimens which have been sawed in two. Greatly reduced. 
 
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 MORE OR LESS IRREGULAR MASSES OF NICKEL-IRON SHALE FOUND ON THE PLAIN AND REPRESENTING 
 
 THE DECOMPOSITION OF SHALE BALL METEORITES, 
 Note what appear to be the remains of Widmanstatten figures in specimen on the right, which has been sawed in two. 
 
 All photographs on this page have been greatly reduced. 
 
 P I A T F y \/ 
 
TYPICAL EXAMPLES OF SMALL SHALE BALL METEORITES WHICH HAVE ESCAPED DISINTEGRATION, 
 WHICH ARE NOW ENTIRELY CONVERTED INTO HARD, DENSE NICKELTRON SHALE. 
 
 BUT 
 
 The middle 
 
 ;p^cimen in upper row represents the pointed end of a considerably larger meteorite than the rest. 
 Such pointed specimens are not infrequently found. Considerably reduced. 
 
 TYPICAL EXAMPLE OF A 
 
 VERY SMALL OVAL SHALE BALL IVIETEORITE 
 INTO NICKEL IRON SHALE, -natural size.' 
 
 NOW ENTIRELY CONVERTED 
 
 TYPICAL PIECES OF HARD, DENSE NICKEL-IRON SHALE FOUND ON ALL SIDES OF THE CRATER IN 
 
 GREAT NUMBERS. 
 Note the curvature indicating that they represent portions of shale ball meteorites '.vhich have disintegrated. Largest 
 specimen in left-hand lower corner about 2'; inches thick. A few specimens have been found much thicker than this and 
 some have been found as thin as a thin knife-blade. 
 
 PLATE XVI 
 
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TYPICAL PIECES OF ORDINARY SMALL CANYON DIABLO SIDERITES, SEVERAL POUNDS IN WEIGHT. 
 
 The specimen on the left shows a tendency to oxidize and originally was doubtless composed largely of shale ball iron. 
 Note the piece of typical nickel-iron shale firmly adhering to the lower right-hand corner. From this and a few other 
 specimens which have been found with a great deal of similar iron shale adhering to them it is inferred that many of the 
 smaller ordinary Canyon Diablo siderites are residuals from the decomposition of larger masses of shale ball iion. 
 
 TYPICAL LARGE CANYON DIABLO SIDERITES. FIGURES REPRESENT WEIGHT IN POUNDS. 
 
 PLATE XVIII 
 
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