il ,tft' > * ' ,,','(,' ",'> '"" I It I 1 1 1 II ^ 1 111*111 tl, 0*1 M ' «(' 'I '> !"" Cornell XHnivetsiti? OF THE IRew l^orF^ State CoIIeae of agriculture %40i.^. :..., nfan. !.t?... 3778" V^^^'VI,^^^'^ Cornell University Library The original of tiiis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924013976828 COLLEGE PHYSIOGRAPHY THE MACMILLAN COMPANY NEW YORK • BOSTON • CHICAGO • DALLAS ATLANTA • SAN FRANCISCO MACMILLAN & CO., Limited LONDON ■ BOMBAY ■ CALCUTTA MELBOURNE THE MACMILLAN CO. OF CANADA, Ltd. TORONTO COLLEGE PHYSIOGRAPHY BY RALPH STOCKMAN TARR LATE PROFESSOR OF DYNAMIC GEOLOGY AND PHYSICAL GEOGRAPHY IN CORNELL UNIVERSITY PUBLISHED UNDER THE EDITORIAL DIRECTION or LAWRENCE MARTIN ASSOCIATE PROFESSOR OF PHYSIOGRAPHY AND GEOGRAPHY IN THE UNIVERSITY OF WISCONSIN THE MACMILLAN COMPANY 1914 All rights reserved L.L. Copyright, 1914, By the MACMILLAN COMPANY. Set up and electrotyped. Published September, 1914. Notioootr iPueg J. 8. Cashing Co. — Berwick & Smith Co. Norwood, Mass., U.S.A. EDITOR'S PREFACE This text-book of College Physiography is written for use in elemen- tary physical geography courses in universities, colleges, and normal schools, for supplementary reference-reading by high school students who are using a more elementary text, and for general reading by lay- men of mature years. The plan of the book is to present, in order, (i) the geographical features of the earth as a planet, (2) the processes in operation and the topographic forms in existence on the lands, (3) the physical geography of the ocean, and (4) the nature and effects of the atmos- phere. Combined with each of these are illustrations of the relations of physical geography to life and especially to man. No attempt has been made to cover all topics simply because they are usually included in a course in physical geography. Instead, each topic is discussed where it naturally comes up in the logical develop- ment of the subject. It is assumed that a certain elementary knowl- edge, for example of latitude, longitude, standard time, the seasons, etc., is retained from grammar school geography or high school phys- iography. They will naturally be reviewed in the laboratory work of a good course in college physiography or, when necessary, can be looked up in a school geography. For schools desiring a shorter list of assignments than is here presented, an abridgment rnight be ac- complished by omitting such matters as the Specific Instances of Volcanic Eruptions (pp. 449-475), Relief Features of the Earth (Chap- ter XVI), or the Earth's Interior (Chapter XVII). It is desirable that both field and laboratory work accompany the study of the text. For courses in advanced physiography or geomorphology, the study of the maps and the reading of selected papers from the original sources listed at the ends of the chapters is recommended. The photographs and diagrams in the text have been chosen with great care and are as well worth study as the text itself. The book was written by the late Professor Tarr, chiefly during the winter 1910-11, although there are indications that he began work on it as early as 1895. He had completed the first draft of the manu- script dealing with th& earth as a planet, the lands, and the ocean be- fore his death on March 21, 191 2. He died suddenly and left no directions as to the disposal of this manuscript. With the approval of Mrs. Tarr and after conference with several of Professor Tarr's more intimate friends among the geographers of the United States, the editor undertook the task of preparing the book for publication. He edited the existing manuscript, added data in connection with new discoveries in physical geography, prepared the illustrations and the vi EDITOR'S PREFACE bibliographies and map lists at the ends of the chapters, and wrote seven chapters to complete the book. These are the chapters dealing with the atmosphere and with terrestrial magnetism. In writing the original twenty chapters the author had followed the outline of the printed syllabus of his course in elementary physical geography at Cornell University. Accordingly this syllabus has been followed in the new chapters, amplified by as many as possible of the illustrative features which Professor Tarr used in his work of instruction at Cornell. In preparing the bibliographies and map lists, use was made of such materials as were left by Professor Tarr, some of them partly drawn up on catalogue cards for use in this book and some published in earlier books, together with some from the editor's own materials used in instruction at the University of Wisconsin. In all respects he sought to carry out the plan and style of presentation which he thought Professor Tarr would have followed in completing the book. In addi- tion to five years of study and teaching at Cornell University the edi- tor had the privilege of intimate association with Professor Tarr in four summers of field work in Alaska and in New York. He also assisted the author in clerical work while he was preparing three of his text-books and collaborated with him in writing two scientific books and a number of technical and popular articles. With this experience in mind constantly, the editor has striven to complete the book along the lines which the author would have followed, although with obvious imperfections in execution. As a matter of professional acknowledgment the editor does not feel that he can do better than to quote the author's own words, from the preface of Tarr's New Physical Geography, written eleven years ago. " It goes without saying that the author is profoundly indebted to the host of workers in physiography, from whom he has drawn so much inspiration, suggestion, and fact : Gilbert, Davis, Powell, Geikie, Penck, de Lapparent, Russell, Shaler, Dutton, Chamberlin, Hayes, Campbell, Salisbury, Brigham, Dodge, Dryer, and many others. From the writ- ings of these physiographers the author has culled whatever seemed to him suited to a scheme of elementary instruction ; and so numerous, and often so unconscious, is the influence of these fellow-workers, that specific acknowledgment would be quite impossible. Doubtless the most profound influence upon the author is that of his two teachers, Professors Shaler and Davis, the importance of which to him cannot be overestimated. Together with other physiographers, the author further recognizes in Professor Davis a leader in American physi- ography, from whom even some of the fundamental principles of the subject have been derived. An examination of the following pages would show the influence of this physiographer in many places, an influence not confined to the pure science, but extending to the pedagogy of the subject as well." The illustrations, many of which are new, are taken from photo- graphs by the author, or pictures taken under his direction by J. O. Martin of Wilbraham, Mass., by O. D. von Engeln of Ithaca, N.Y., EDITOR'S PREFACE vii by the editor of this volume, and others. A number were purchased for use in this and earher books by the author, the collections of cer- tain American physiographers, and of the United States Geological Survey, the department of geology at Cornell University, W. H. Rau of Philadelphia, F. J. Haynes of St. Paul, S. R. Stoddard of Glens Falls, N.Y., and the Detroit Photographic Company supplying a great many. The photographer's name, where known, appears in the legends of the illustrations. Most of the foreign photographs were purchased in Europe by the author. Many of the photographs by the author and the editor were taken under the auspices of the National Geographic Society of Washington,, the American Geographical Society of New York, and the United States Geological Survey. Most of the models are by the late E. E. Howell of Washington. A large proportion of the block diagrams were drawn by C. W. Furlong of Boston. Mr. E. F. Bean of the University of Wisconsin helped materially in prepar- ing the illustrations. ' Acknowledgment is particularly due to Professor R. de C. Ward of Harvard University, who was good enough to read the manuscript of the six chapters dealing with the atmosphere, and to Dr. L. A. Bauer of the Carnegie Institution of Washington, who kindly read the man- uscript of the chapter on terrestrial magnetism. Each of these gentle- men made valuable criticisms and suggestions, but the editor takes full responsibility for any shortcomings in these chapters. The editor feels keenly the responsibility which he is incurring by preparing this book for the press, for the author's reputation is so high that nothing should be done that could possibly mar it. Professor Tarr prepared only the first draft of twenty out of the twenty-seven chapters. His experience in twenty years of college teaching, his facihty in writing, and especially in writing three successful high school physiographies, a laboratory manual of physical geography, an elementary geology, an economic geology of the United States, a series of grammar school geographies, a regional geography of his own state, three scientific books on physiography, glaciers, and earth- quakes in Alaska, and scores of technical and popular articles, based upon his investigations in various parts of North America and Europe, all qualified him to produce a book of the first quality. Had he lived to complete it, there would surely be an improvement along many lines ; but, as it is, the book must stand upon its merits. LAWRENCE MARTIN. Madison, Wisconsin, July 13, 1914- CONTENTS Introduction PAGE xv-xxii PART I. THE PLANET AND THE LANDS CHAPTER I. Fundamental General Facts . n. Weathering and Rock Disintegration in. The Work of Winds IV. The Work of Underground Water V. Rivers and River Valleys VI. River Deposits . • . . VII. The River Valley Cycle VIII. Glaciers and Glaciation IX. The Glacial Period . X. Lakes and Swamps XI. Shorelines XII. Movements ok the Earth's Crust, or Diastrophism XIII. Vulcanism .... XIV. Plains and Plateaus XV. Mountains XVI. Relief Features of the Earth : XVII. The Earth's Interior XVIII. Terrestrial Magnetism . 37 57 76 100 141 171 197 256 308 342 389 438 497 525 583 611 629 PART n. THE HYDROSPHERE- XIX. The Ocean . . . XX. Life in the Ocean . XXI. Movements of the Oceanic Water 637 669 682 PART in. THE ATMOSPHERE XXII. Characteristics of the Atmosphere .... 709 XXI II. Light and Warmth in the Atmosphere . 715 XXIV. Rain and Other Forms of Water . . . -733 XXV. Winds .... .... ^ 746 XXVI. Storms .... 759 XXVII. Climate .......... 783 INDEX .... 815 ix LIST OF COLOURED MAPS PLATE NAME FEATURES SHOWN FACING PAGE I. Turtle' Mountain and Frank, Alberta landslide 52 II. Niagara Falls and Gorge waterfall 130 III. Mississippi River .... floodplain . 144 IV. Bering Glacier piedmont glacier 242 V. Harriman I~iord mountains and fiord 286 VI. Coast of California . shorelines . 348 VII. Vesuvius volcano 454 /III. Grand Canyon of the Colorado canyon and plateau S16 IX. Yosemite Valley mountain valley 548 X. Boston and Vicinity peneplain and harbours 598 ACKNOWLEDGMENT OF ILLUSTRATIONS In addition to the credit'' for illustrations given in the Preface and in the legends of the half tones and text figures, acknowledgment is due the follow- ing authors and publishers for kindly permitting the use of illustrative material and, in several cases, for supplying electrotypes. The numbers below refer to figures in this book. Bowman's Forest Physiography, John Wiley & Sons, New York, — Figs. 28, 183, 290, 351, 358, 362. 367, 378, 468. Davis's Elementary Afeteorology, Ginn & Co., Boston, — Figs. 429, 500. Davis's Erklarende Beschreibimgder Landformen, B. G. Teubner, Leipzig, — Fig. 150. de Martonne's Traite de Geographic Physique, Armand Colin, Paris, -^ Figs. 379. 392. 412- Encyclopedia Britannica, University of Cambridge Press, — Figs. 14, 77, 170, 387, 442. Herbertson and Taylor's Oxford Wall Maps, Henry Frowde, London, — Fig. 486. Hobbs's Earth Features and their Meaning, Macmillan Co., New York, — Figs. 36, 54. 59, 73. 139. 162, 164, 165, 166, 173, 181, 184, 190, 196, 221, 237, 25s, 257. 261, 278, 279, 280, 283, 289, 296, 322, 336, 384, 433. The editor of this volume, — (Photographs), Figs, i, 122, 128, 136, 138, 151, 153. 175, 176, 202, 203, 231, 360, 363, 376; (Maps and Diagrams), Figs. 123, 126, 143, 154, IS5. 156, 159' 195. 227, 272, 276, 286, 364, 377. Milham's Meteorology, Macmillan Co., New York, — Figs. 424, 457, 465, 470, 477, 495. 498- Moulton's Introduction to Astrono7Hy, Macmillan Co., New York, — Figs. 7, 8, 389- Murray and Hjort's Depths of the Ocean, Macmillan & Co., London, Fig. 398. Murray's The Ocean, Henry Holt & Co., New York, — Figs. 390, 391, 395, 408, 413. Scott's Introduction to Geology, Macmillan Co., New York, — Figs. 17, 211, 277, 292,304. Todd's New Astronomy, American Book Co., New York, — Fig. 1 1 . Ward's Practical Exercises in Elementary Meteorology, Ginn & Co., Boston, — Figs. 460, 502. Ward's Climate, Considered Especially in Relation to Man, G. P. Putnam's Sons, New York, — Figs. 431, 435. 447. 483. 484. 492. S°3- Wyoming Historical and Geological Society ; also Connecticut Geological and Natural History Survey, diagrams by J. Barrell, — Figs. 345, 346. INTRODUCTION THE EARTH SCIENCES The earth consists of three quite distinct portions, a solid central mass, a partial envelope of liquid, and a complete blanket of gases, each of which is the seat of a series of interesting phenomena. Their investigation has attracted the thoughtful attention of many scientific men, both in the past and at present. The study of the gaseous por- tion, or atmosphere, has led to the development of Meteorology, and one phase of this study has been recognized as the science of Clima- tology. The science of the study of the waters is called Hydrography, and of that larger part of the Uquid envelope which occupies the ocean basins. Oceanography. Several distinct sciences deal with the study of the soUd earth itself. For example. Mineralogy concerns itself with the minerals of which this soUd earth is composed ; and Petrology with the study of the rocks of the earth ; while the study of certain special phenomena has given rise to special sciences with limited scope, such as Seismology, which is concerned with a study of earthquakes, and Vulcanology, with volcanic phenomena. But the two chief sciences dealing with the sohd earth are Geology and Geography, and each of these is concerned also, to a certain extent, with the waters and the air. These are, therefore, of broader scope than either of the other sciences, since they involve, to a degree, a consideration of the earth as a whole, not a single phase of it. Geology deals with the past history of the earth and its development through the ages. Geography, on the other hand, is concerned with the present condition of the earth in its relation to life. One of the divisions of geography is called Physical Geography, or, sometimes. Physiography, which may be defined as that science which investigates the physical features of the earth and their influence on life, especially man. It is a fundamental part of geography, and basal to any scien- tific study of that subject. To some, it seems difficult of separation from geology, and in certain of its aspects it might indeed be considered the latest chapter in geology, — the history of the present surface of the earth, or Geomorphology. But it is broader than this, for it deals not merely with the latest chapter in the history of the earth, but also with the influence of the surface features on human and other life, and the interaction and interrelation between air, water, land, and life. Physical geography is an integral part of geography, and not to be separated from it, having independent subrank under the larger whole, side by side with Political Geography, Anthropogeography, etc., and xvi INTRODUCTION having for its special field the more physical aspects of geography, as its name indicates. Dealing as it does with air, land, and water, physical geography of necessity draws from meteorology, geology, and oceanography for some of its facts and methods, and even for some of its field of investigation. Did it not do so, it could be little more than a descriptive science, telling merely what the earth's surface is, and leaving to other sciences the statement of how it came to be. In the study of the land in particular, it is necessary to borrow from geology, for no interpretation of the present surface features is possible without a knowledge of at least some of the past events by which they have come to be. The Principle of Vast Lapse of Time One of the most fundamentally important contributions to an imder- standing of the history of the earth is the proof which geologists have presented of the vast lapse of time during which this earth history has been in progress. It is equally fundamental to an understanding and interpretation of the surface features of the earth with which physical geography has to do. So long as it was thought that the age of the earth was to be numbered in a few thousand years, no real progress was possible, either in unravelling its history or in interpreting the earth forms by which man is surrounded. It has now been demon- strated, by a series of proofs that are incontrovertible, that the age of the earth is to be reckoned in millions of years, and that even those slowly operating processes with which we are surrounded, and which, in a human life-time, may not cause visible change, are capable of performing vast tasks and of bringing about great changes, when in incessant operation through not merely hundreds of years, but tens of thousands and hundreds of thousands of years. The acceptance of this principle, which during the last century required long and heated argument to establish, and the patient accumulation of a great mass of observations . before it was finally and universally accepted even by scientific men, is fundamental to an appreciation of the phenomena of the surface of the earth. It is as basal a principle in geology and physical geography as a broad concep- tion of the distances in space is basal to astronomy. In both cases the full appreciation of the conception is denied the human mind, for in his experience man deals only with inches, feet, and miles, and with seconds, minutes, and years. It is, therefore, quite beyond our power to fully reahze the true significance of the 92! miUion miles which sep- arate the sun and earth, or the scores of millions of years which sep- arate us from the early ages of geological time. Yet the one is as truly a fact as the other, and neither the principles of astronomy nor of physical geography can be really appreciated without accepting as a basal principle the measure of the space or the time which lies far beyond our limited range of experience. The principle is so well INTRODUCTION xvii established that it may fairly be stated as such without a preliminary attempt at proof," leaving the verification to appear as the subject is developed. Development of Physical Geography The development of science, in general, up to its present standard was primarily the work of the last century, though it was preceded by a series of brilliant discoveries, notably of basal principles in astronomy and physics. The study of the earth, partly descriptive, had occupied the attention of many workers in the preceding centuries ; and natu- rally the phenomena of the earth upon which man Uved, and by which he was surrounded, led to some investigation and to still more specu- lation, often most fantastic. Thus earthquakes, volcanoes, fossils in the rocks, and other phenomena early attracted attention and were subjects of investigation and speculation ; and naturally the question of the origin of the earth itself was a source of interest and wonder which led to speculation, as is proved by the cosmologies of the an- cients, and the even more vague speculations of more primitive peoples. Although much thought had been given to the subject, and much had been written upon it and some important facts and principles had been put forward by the beginning of the last century, there had been httle real progress in the development of any phase of earth science up to the beginning of the ■ nineteenth century. This lack of progress was in part due to the general unorganized state of science. TMs affected all sciences to almost equal extent. It was even further due to the prevalence of the fundamental fallacy that the cosmology presented in the first chapter of Genesis was to be taken literally, and was to serve as the basal principle in an interpretation of earth history. It required more than ordinary evidence to overcome this fallacy, for it was given the stamp of infallibility by theological dogma. Any facts that'seefn«d to controvert the Jewish cosmology must needs be thrown out ; aMany argument based upon such facts was regarded as an attack upon the very foundation of religious belief. There arose, therefore, a conflict between science and religion, or, as White better phrases it, a "Warfare of Science with Theology." This conflict just alluded to led to bitter controversy, increasing in extent and intensity in the first half of the nineteenth century, and not com- pletely extinguished even in the second half, though now, happily, almost completely at an end. There were also bitter controversies among geologists, of which one of the most serious was between the school of Werner, a German, and Hutton, a Scotchman. The former held that the earth had developed its present form with rapidity through a succession of catastrophic phenomena in which water was the prime agent, and the Wernerian School became known as the Neptunists. Hutton held that the present earth form was the result of slower evolution in which both water and xviii INTRODUCTION heat were involved, and his school became known as the School of the Vidcanists. In its main elements, the theory of Hutton has prevailed; and to it we may look for some of the basal principles of the physical geography of the lands. Playfair's " Illustrations of the Huttonian Theory of the Earth," pubUshed in 1802, is the real beginning of the modern physical geography, for it postulates the idea of vast lapse of time in which " we can see neither the beginmng nor the end," the importance of the forces at present in operation, when operating through long periods of time, the true origin of river valleys, and other basal principles of physical geography. For a generation, so bitter was the controversy, and so opposed was the Huttonian theory to the supposed demands of true religion, that the brilliant assemblage of facts and logical deductions from them put forward by Hutton, Playfair, and others, failed of acceptance and apparently left little or no impression upon the science of the time. The Huttonian theory was revived, elaborated, and amplified in 1830 in Lyell's " Principles of Geology." He fostered it with all the vigour of his brilliant mind. Primarily by Lyell's work, aided by the re- searches of a number of other students of earth science, the Huttonian principle became established, and the doctrine of Uniformitarianism, as opposed to that of Catastrophism presented. With some modifica- tion in detail it is basal to the study of the development of the surface forms of the earth. This doctrine holds that by the processes of the present, working through the lapse of time, the present features of the earth have been evolved; and that catastrophes, though probably occurring, are not essential to the underlying causes. In the further development of physical geography a multitude of workers have taken part in bringing it to its present standard. This is not the place to attempt to trace the development of the subject in detail, nor to list the names and contributions of the principal workers. The names of three Americans, — Gilbert, Powell, and Davis, — however, stand out with such special prominence in the history of the development of modern physical geography that they call for mention even in this generalized view. In two reports, written at about the same time, 1875, — Gilbert's chapter on Land Sculpture ■in " The Geology of the Henry Mountains " and Powell's " Explora- tion of the Colorado River of the West," — there are stated for the first time some of the underlying principles of land sculpture, upon which the scientific study of the surface of the earth is based. Pro- fessor Davis has added still other principles, has outlined and de- veloped the idea of the progressive stage in the development of land forms, and has given to physical geography an organization which has won many followers, including the writer of this book, who was fortunate enough to be one of his early pupils, and at the same time to come under the inspiring influence of that great teacher and geog- rapher. Professor N. S. Shaler. Some of Professor Davis's papers have been collected in a single volume entitled " Geographical Essays," INTRODUCTION xix 1909; see also Davis's "Physical Geography," 1898; "Practical Exercises in Physical Geography," 1908 ; " Grundziige der Phys- iogeographie," 191 1; " Erklarende Beschreibung der Landformen," 1912. In a study of the air and of the oceans, as well as of the lands, many men have been at work, and the development of the sciences of the air, ocean, and land is dependent upon the combined effort of them all, though with some more potent than others in the discovery, veri- fication, and exposition of imderlying principles. Modern physical geography has developed out of the work of this army of students, specific reference to some of whose contributions wiU appear in the succeeding chapters of this book. References to Literature The literature of physical geography is extensive. Among the writ- ings upon the subject are elementary school textbooks, special articles upon particular processes or areas, books upon special topics such as rivers, earthquakes, etc., books and articles relating specifically to the atmosphere and the oceans, and books of a general nature. Ref- erence to all but the first of these classes of publications will be foimd in later pages, but there are a number of publications of such a general nature that they are Usted below, mainly of books and magazines, relating specifically to the Physical Geography of the Lands, deferring reference to the atmosphere and oceans to those sections dealing spe- cifically with these topics. The list also includes a few books on human geography. This subject is discussed incidentally throughout the book along the line of the splendid contributions by Friedrich Ratzel, EUsee Reclus, J. Brunhes, and others in Europe, and Miss E. C. Semple, A. P. Brigham, and others in America. It is not claimed that the fol- lowing list is complete, nor that it has included all that are of impor- tance and value. PHYSICAL GEOGRAPHY John Playfair. Illustrations of the Huttonian Theory of the Earth, Edin- burgh, 1802. Karl Ritter. Die Erdkunde, Berlin, 1817. Sir Charles Lyell. Principles of Geology, ist edition, 1830; nth edition, 2 vols.. New York, 1873. , x , A. von Humboldt. Cosmos, 1844 ; edition m English, 5 vols., London, 1871-1872. J. P. Lesley. Manual of Coal and its Topography, Philadelphia, 1856. J. W. Powell. Exploration of the Colorado River of the West, Chapters XI and XII, Washington, 1875- , , „ ^^ . ■ r^^. . -.r G. K. GUbert. Report on the Geology of the Henry Mountains, Chapter V, Washington, 1877. T H Huxley. Physiography, London, 1877. O. Peschel and G. Leipoldt. Physische Erdkunde, 2 vols., Leipzig, 1880. F. von Richthofen. Fuhrer fur Forschungsreisende, Berlin, 1886, 1901. A. GeiJde. The Scenery of Scotland, London, 1887. XX INTRODUCTION G. de la Noe and Emm. de Margerie. Les Formes du Terrain (with atlas of plates), Service Geographique de I'Armee, Paris, 1888. N. S. Shaler. Aspects of the Earth, New York, 1889. S. Gunther. Lehrbuch der Physikalischen Geographie, Stuttgart, 1891 ; Handbuch der Geophysik, 2 vols., Stuttgart, 1897, 1899. H. R. Mill. The Realm of Nature, New York, 1892. T. G. Bonney. Story of Our Planet, London, 1893. J. Geikie. Fragments of Earth Lore, Edinburgh, 1893. N. S. Shaler. Sea and Land, New York, 1894. A. Penck. Morphologie der Erdoberflache, 2 vols., Stuttgart, 1894. J. W. Powell and Others. Physiography of the United States, National Geographic Monographs, New York, 1896. Andrew D. White. History of the Warfare of Science with Theology in Christendom, 2 vols.. New York, 1896. A. de Lapparent. Legons de Geographie Physique, Paris, 1896. C. R. Dryer. Studies in Indiana Geography, Terre Haute, 1897. E. Bruckner. Die Feste Erdrinde und ihre Formen, Leipzig, 1897. N. S. Shaler. Outlines of the Earth's History, New York, 1898. J. Geikie. Earth Sculpture, London, 1898. Henry Gannett. Topographic Atlas of the United States. U. S. Geol. Survey, — Folios I and 2, Physiographic Types, 1898, 1900; Folio 3, Physical Geography of the Texas Region, by R. T. Hill. J. E. Marr. The Scientific Study of Scenery, New York, 1900. A. J. Herbertson. Outlines of Physiography, London, 1901. R. S. Tarr. The Physical Geography of New York State, New York, 1902. J. Lubbock (Lord Avebury). The Scenery of England, New York, 1902. A. Robin. La Terre, Paris, 1902. H. Wagner. Lehrbuch der Geographie, 7th edition, Leipzig, 1903. E. Suess. Das Antlitz der Erde ; edition in English, " The Face of the Earth," translated by SoUas, 4 vols., Oxford, 1904-1912; the French edition, " La Face de la Terre," translated under the direction of the eminent Emm. de Margerie, is the best of the three because of the many additional illustrations and references to literature. A. Hettner. Grundziige der Landerkunde, Vol. I, Europe, Leipzig, 1907. J. van Baren. De Vormen der Aardkoorst, Groningen, 1907. R. D. Salisbury. Physiography, New York, 1907. ' R. D. Salisbury and W. W. Atwood. The Interpretation of Topographic Maps, Prof. Paper 60, U. S. Geol. Survey, Washington, 1908. J. W. Gregory. Geography — Structural, Physical, and Comparative, Lon- don, 1908. W. M. Davis. Practical Exercises in Physical Geography (with atlas), Boston, 1908. E. de Martoime. Traite de Geographie Physique, Paris, 1909, 1913. Gen. Berthaut. Topologie, Etude du Terrain, 2 vols., Service Geographique de I'Armee, Paris, igog. W. M. Davis. Geographical Essays, Boston, igog. A. Supan. Grundzuge der Physischen Erdkunde, Leipzig, 1911. W. M. Davis. Erklarende Beschreibung der Landtormen, Leipzig, igi2. S. Passarge. Physiologische Morphologie, Mitt. Geog. Gesell. in Hamburg, Band 26, Heft 2, 191 2. J. Brunhes, E. Chaix, Emm. de Martonne and Others. Atlas Photo- graphique des Formes du Relief Terrestre, Geneva, 1914 to date. HUMAN GEOGRAPHY Arnold Guyot. The Earth and Man, Boston, 1849. Karl Ritter. Geographical Studies, Boston, 1863; Comparative Geography, Philadelphia, 1865. INTRODUCTION xxi G. P. Marsh. The Earth as Modified by Human Action, New York, 1863, 1874. O. Peschel. Races of Man, New York, 1876. E. Rectus. La Terrc, ^ vols. ; Nouvelle Geographic Universelle, 19 vols., Paris, 1878-189S,— published in English as The Earth and Its Inhabitants ; L'Homme et La Terre, 6 vols. E. A. Freeman. Historical Geography of Europe, London, 1881, 1903. J. Ltibbock (Lord .\vebury). Origin of Civilization, New York, 1886. A. Kirchhofi. Unser \\'issen \-on der Erde, 5 vols., Leipzig, 1886-1890; Man and Earth, London, 1906. G. G. Chisholm. Handbook of Commercial Geography, ist edition, 1889; 6th edition, London, 1906. F. Ratzel. Anthropogeographie, 2 vols., Stuttgart, 1891, 1899; The History of Mankind, 3 vols.. New York, 1896-1898; Die Erde und Das Leben, 2 vols., Leipzig, 1901 ; Politische Geographic, 2d edition, Munich, 1903. N. S. Shaler. Nature and Man in America, New York, 1891 ; Man and the Earth, New York, 1905. E. Stanford. Compendium of Geography and Travel, 2d edition, 12 vols. 1893-1901. A. H. Keane. Ethnology, 2 vols.. New York, i8g6; Man, Past and Present, New York, 1899. W. Z. Ripley. Races of Europe, 2 vols., New York, 1899. H. R. MUl and Others. International Geography, New York, 1899. H. B. George. Relations of Geography and History, Oxford, igoi. H. J. Mackmder. Britain and the British Seas, New York, 1902. A. P. Brigham. Geographic Influences in American History, Boston, 1903 ; From Trail to Railway Across the Appalachians, Boston, 1907. J. Partsch. Central Europe, New York, 1903. E. C. Semple. American History and Its Geographic Conditions, Boston, 1903; Influences of Geographic Environment, New York, 1911. A. Geikie. Landscape in History, and Other Essays, London, 1905. J. Bnmhes. La Geographie Humaine, Paris, 1910. H. E. Gregory, A. G. Keller, and A. L. Bishop. Physical and Commercial Geography, Boston, 1910. C. R. Van Hise. Conservation of Natural Resources in the United States, New York, 1910; Mineral Resources in Civilization (in press). J. R. Smith. Industrial and Commercial Geography, New York, 1913. PERIODICALS Bulletin of the American Geographical Society, New York. Annals of the Association of American Geographers. Geographical Journal, London. Scottish Geographical Magazine, Edinburgh. Annates de Geographie, Paris. La Geographie, Paris. Revue de Geographie, Paris. Petermann's Mitteilimgen, Gotha, Germany. Zeitschrift der Gesellschafl fiir Erdkunde zu Berlin. Geographische Zeitschrift, Leipzig. Milteilungen der Geographischen Gesellschafl in Wien. Bollettino delta Reale Societa Geografica, Rome. Bulletin of the Geographical Society of Philadelphia. Appalachia, Boston. National Geographic Magazine, Washington. Geographical Teacher, London. Journal of Geography, Madison, Wisconsin. xxii INTRODUCTION BIBLIOGRAPHIES V . S. Geological Survey. Catalogue and Index of Contributions to North American Geology, 1732-1891, — Bulletin 127, U. S. Gaol. Survey, 1896, by N. H. Darton; the same continued from 1892 to 1912 by F. B. Weeks and by J. M. Nickles as Bulletins 188, 189, 301, 372, 409, 444, 495, 524, and 545. Royal Society of London. International Catalogue of Scientific Literature, annual bibliographies of Geography and Geology. Gesellschaft fiir Erdkande zu Berlin. Bibliotheca Geographica, published annually. Geographisches Jahrbuch and Geographen Kalendar, Gotha, Germany. Annates de Geographie. Bibliographie Geographique annuelle. Geographical A ssociation. Guide to Geographical Books and Appliances, by H. R. Mill, A. J. Herbertson, and others, London, igio. COLLEGE PHYSIOGRAPHY PART I. THE PLANET AND THE LANDS CHAPTER I FUNDAMENTAL GENERAL FACTS The Earth as a Planet The Solar System. — The earth is one of a vast number of spheres in space, about most of which relatively little is known. A small group of these spheres, revolving about a central body, the star which we know as the sun, are better known, and together constitute the solar system. Omitting (a) occasional visitors to the solar system, or comets, {b) the small spheres or asteroids, (c) the still smaller meteo- rites, and (d) the rings of Saturn, there remain three quite distinct classes of bodies as constituent parts of the solar system: (i) the central sun, (2) the planets, (3) the sateUites. Similarities of Members of the Solar System. — Among the spheres that revolve about the sun, and especially the eight moderate- sized spheres called planets, there is a striking uniformity in some important respects. First and foremost, each has a spherical form. This is familiar in the case of the earth from the proofs in connection with (a) the cir- cumnavigation of the globe, (b) the method of disappearance of ships upon the sea, and (c) the curved shadow of the earth during an eclipse of the moon (Fig. 2), as was well known to some of the ancients. Each planet is distorted by protuber- ance in the equatorial region into the form of an oblate spheroid. Secondly, all are rotating about an axis inclined to the plane through which they are revolving about the central body inclination of the axis and the rate of rotation vary from sphere to sphere In the third place, they are all engaged m a revolution about Fig. 2. — Proof of the roundness of the earth from curved shadow during eclipse of moon. (Photograph by Harvard College Observa- tory.) but the COLLEGE PHYSIOGRAPHY Fig. 3. — Relative sizes of the four larger planets. EARTH the central body, the sun, following an elliptical path, or orbit; while the satellites, in addition, are revolving about the planet to which they are attached. A -JhMj'- fourth resemblance is that they all receive their light and heat from the central suil, though in amounts varying with the dis- tance. Finally, it is probable, though not certainly proved, that all these spheres are composed of essentially the same materials. Contrasts within the Solar System. — While there are these resem- blances, there are also notable differences. The spheres differ greatly in size (Figs. 3, 4), ranging from the sun, with a diameter of 860,000 miles (Fig. 9), to the earth, with about xiir this diameter, and the satellites with diam- eters of but two or three thousand miles, and to the still smaller asteroids. They differ also in their distance from the sun, and consequently in the length of the orbit through which they circle about it, as well as in the time required to complete the revolution (Fig. 5). Thus Mercury, the planet nearest the sun (Fig. 6), being approximately 36,000,000 mUes distant, requires about 88 days for its journey about the sun; the earth, 92,750,000 miles distant, re- quires a little over 365 days, determin- ing the length of our year; and Neptune, the most distant planet, 2,775,000,000 miles from the sun, requires about 165 years for its revolution. A third noteworthy difference among the members of the solar system is the different periods of rotation, the earth turning on its axis in about 24 hours, and, therefore, determining the length of a day, while the; sun rotates in 25 days, the moon in 27I days, and Jupiter in 9 hours and 55 minutes. That the earth does rotate from west to east upon its axis was long ago Fio. 4. — Sizes of the four smaller planets, given in diameters in miles. FUNDAMENTAL GENERAL FACTS demonstrated by Galileo. In investigating the behaviour of objects falling through the air, he discovered that they always fell a Uttle to the east of a point directly below that from which they were dropped (Fig. 7). At the Leaning Tower of Pisa, for example, the rotation of the earth causes an object at the top of the tower to move faster than one at its base, as Galileo correctly reasoned. The proof of the earth's rotation by Fou- cault's pendulum. (Fig. 8) was first carried out in 1851 and is repeated every year in the physics or the geography departments of many Fig. -Diagram showing the time required for each planet to revolve around the sun. III IU< < =h^-f^- , '-Ml.OOO.OW I --93JWO.000 I --67.000.000 — ac.wjOjOOO ' — 430.000.000 2.775,000,000" FiG. 6. — Diagram showing the distance from the sun to the various planets in miles. colleges. Foucault's method was to Suspend a heavy weight from the dome of the Pantheon in Paris, and set it to swinging. A pendu- Itma will continue to swing indefinitely in exactly the same plane. After being set in motion it appears to cease to vibrate parallel to a mark on the floor, gradually comes to a posi- tion of swinging at right angles to the mark, and, in 24 hours or a little more, depending on the part of the earth, it seems to shift until it once more swings parallel to the mark. This is because the building turns around the pendulum as the earth rotates. Still another contrast within the solar system is the condition of the spheres. On some, like the earth and Mars, there is an atmosphere, while on others, like the moon, there is no gas- eous envelope. There seems also to be a grada- tion in temperature from the highly heated sun to the completely cold moon, with intermediate stages, such as Jupiter, which is evidently highly heated, though not glowing, and the earth, which, though cold at the surface, is apparently heated withm. Fig. — To show the deviation of falling bod- ies. (After Moulton.) An object dropped from the tower MF reaching the earth at P rather than at F'. 4 COLLEGE PHYSIOGRAPHY Ftg. 8. — To show the rela- tions of Foucault's pendu- lum to the rotating earth at the pole P, il it were started swinging in a plane parallel to the meridian m. (After Moulton.) While it does not fall within the province of Physical Geography to study the other members of the solar system, no presentation of this subject would be complete which ignored the resemblances and relationships which exist between the members of the great family of spheres which constitute the solar system. Nor would any attempt to understand the origin of the phenomena of the earth itself be fruitful without utilizing at least some of the facts which astronomers have contributed as a result of their study of the members of the solar system. The Earth in the Solar System. — The earth is an integral part of this system ; its move- ments in space are influenced and guided by its relation to other members of the great family of spheres ; its light and heat, its tides, and winds and rains, together with the changes of the earth's surface, which result from their presence and action ; and even the direct result of the astronomical relations of the earth and its history of development as a planet, — can be understood only by considering it as one of a series of spheres of common character and common origin. Earth and Sun. — There is a difference in the degree of importance of the relationships between the earth and its fellow members of the solar system, and from the stand- point of the study of Physical Geography we may ignore all other relationships excepting those be- tween the earth and the moon and the sun. To the sun the earth is bound by the tie of gravi- tation, which holds it to its ellip- tical orbit, as the moon is held to its orbit around the earth. Across the space of about 92I million miles, radiant energy passes from the sun, which shines in the heav- ens and like the other stars is fiery hot, to the surface of the earth, which merely reflects sunlight as the moon does. This radiant en- ergy produces the phenomena of heat and light. Magnetic waves also span the distance, giving rise to phenomena upon the earth whose full significance is not yet understood. By the inclination of the earth's axis to the plane of the ecliptic, the plane in which the earth moves in its revolution around the sun, the Fig. 9. — Diagram to show vast size of the sun compared with the earth. If the earth and moon and orbit of the moon were placed inside the sun, the relation- ship would still be as shown above. FUNDAMENTAL GENERAL FACTS 5 distribution of light and heat, which on a sphere would otherwise vary regularly from equator to pole, varies within other limits. These limits are constantly changing during the revolution of the earth about the sun; and, since the inchnation is 23^° from the verti- cal, shift from a point 23^° north of the equator to a point 23^° south of the equator. Thus arise our seasons with all their momentous consequences. Among the consequences of inchnation is this. It happens that we have found it convenient to bisect the distance between the North and STANDAED TIME IN THE UNITED STATES Fig. 10. — The belts usually adopted in the United States. South Poles, at the ends of the earth's axis, by an equator, and to sub- divide it further a,long the line of parallels of latitude, among which the Tropics of Capricorn and Cancer and the Arctic and Antarctic Circles are definitely related to the inclination of the earth's axis. Because of the period of daily rotation of the earth (23 hours and 56 minutes) the point upon which the sun's rays strike vertically is constantly and steadily shifting eastward, and thus in a day a line is traced around the earth upon which the sun's rays strike vertically, making it convenient, among other things, to have meridians of longi- tude, reckoned from the arbitrarily chosen prime meridian at Green- wich. The parallels and meridians are divided into degrees, and these are divided into minutes and seconds. A degree of longitude at the equator is about 69I miles ; in the latitude of Philadelphia, Denver, Madrid, Peking, and New Zealand it is only about 53! miles ; in the latitude of St. Petersburg it is about 35 mUes ; and at the poles it has ,.^^^ ^■^ -^ 1 1 1 \ \ O ,x^ \ \ \ Q \ !^-«|, sr*^^^^^ "summer Fig. II. — Diagram to show why the sun appears to rise farther north in summer than winter. (From Todd's " New Astronomy.") ^0m^ '^'5*i;s>' Fig. 1 2. - Diagram to show the portions of the earth illuminated at various seasons during revolution around the sun. FUNDAMENTAL GENERAL FACTS 7 no length. A degree of latitude varies in length from 68.7 to 69.4 miles, because of the earth's polar flattening. As a result of the earth's daily rotation it is also necessary for us to have Standard Time (Fig. 10). From the point of verticality of the sun's rays the angle at which the rays reach the earth is lower and lower in each direction. With the change of seasons (Fig. 12) the line of verticaUty shifts / \ northward and southward, / \ from the Tropic of Cancer / Z' X on the north to the Tropic Earth ( Maonmo] looo of Capricorn on the south. I I j Accordingly the sun appears \ \^__^^ to rise farther north in sum- \ mer in the northern hemi- ■snhprp than in wintpr