XXIII. GEOLOGY, METEOROLOGY, TERRESTRIAL MAGNETISM, AND GEOGRAPHY GEOLOGY STRUCTURAL AND DY NAMIC J. B. WOODWORTH Structural. The broad structural and stratigraphic features of the North American continent have been known now for nearly a quarter of a century, yet at no time in the past of American geological science have such strides been made in the interpretation of the stratified rocks and mountain built structures as have been witnessed by the opening years of the century. Dynamical geology has also been enriched either by new concepts gained from American studies or by the application to local problems of the theoretical gains accomplished by fellow geologists in other lands. Among the causes which have contributed to this advance must be recognized the writings of Edouard Suess, generally neglected in America prior to the appearance of the French translation by DeMargerie and his confrères, and the recent English rendering under the title The Face of the Earth, by Prof. Sollas. To this work may be traced a stimulation of thought concerning the larger problems of the earth's outer architecture, especially in the matter of lateral displacement or creep of the earth crust in mountain belts. F. B. Taylor discusses (in Bulletin of the Geological Society of America, Vol. XXI), with Suessian sweep of view, the crustal creep of the Tertiary mountain belt of the world. Reudemann, in the Annual Report of the New York State Museum for 1909, directs attention to the symmetrical arrangement of the land elements of the paleozoic plat form of northeastern North America regarding the area as modified in structure by ancient pressures from the Atlantic region in a manner to give rise to the Appalachian basin folds and the Cincinnati uplift or parma. W. Joerg (Bulletin of the American Geographical Society, Vol. XLII), also with the views of Suess in mind, divides the northern portion of the Rocky Mountain region into districts displaying diverse pressure effects. A second prominent factor in the advanced thought of the present period was introduced in the work of Prof. Chamberlin largely embodied in the text-book of geology by Chamberlin and Salisbury, in which the whole structure of the globe is stated anew in the terms of the planetesimal hypothesis. In the Journal of Geology, Vol. XVIII, R. T. Chamberlin, le fils, following out suggestions made in that work, attempts on the basis of the modern detailed sections of the folded Appalachian chain to determine the thickness of the rock shell involved in mountain building, which thickness, on the basis assumed, amounts to 5.17 miles. Stratigraphic Geology.-In the field of stratigraphic geology where fossils constitute the basis of establishing a chronology, a most important paper has appeared in the Bulletin of the Geological Society of America by Prof. Scheuchert, of Yale. The author sets forth the results of many years' detailed study of the vertical and horizontal distribution of American fossils, and presents a series of hypothetical maps of the distribution of land and sea from the Cambrian to the recent period, embodying many alterations in the formerly conceived outlines of the successive stages of continental evolution. In this work recognition is made of the large amount of nonmarine sediment which enters into the geological column, the identification of which has been facilitated by the recent critical essays of Prof. Barrell, of Yale. As a result of his own investigations Prof. Scheuchert finds reasons for revising the American formation scale and proposes a somewhat radical subdivision of the stratigraphic succession. Closely related to this paper is the vice presidential address of Mr. Bailey Willis before section E of the American Association for the Advancement of Science at its Boston-Cambridge meeting (Science, Vol. XXXI). In this paper the principles of paleography or the reconstruction of the past outline of continents and ocean basins are discussed more from the point of view of the geologist than that of the paleontologist. Mr. Willis holds with most English-speaking geologists that the great ocean basins, are permanent features of the earth's surface, and they have existed, where they now are, with moderate changes of outline, since the waters first gathered." One cannot but remark here the fixity of this idea in England and the United States, in contrast with the much greater latitude of change postulated by the geologists of continental Europe, particularly in the case of the Atlantic Ocean. The feature is so striking as to constitute the division of geologists into two schools, in which dynamical concepts have a strongly marked geographic setting. Willis, in touching upon the generally mild climates of the globe, as contrasted with glacial periods, appears to recognize the possibility of a change in the existing oceanic circulation being brought about as suggested by Chamberlin in 1906. Chamberlin pointed out that if the oceanic circulation were reversed so that the warm highly saline waters of the equatorial regions sank and flowed poleward with a compensating equatorward creep of the chilled polar sea water, an explanation would be afforded of the uniform sea temperatures indicated by the faunas and floras of the past. Pertinent to the question of past climate in this connection is the note by David White and Knowlton (Science, XXXI), stating as their conclusion, based upon a study of fossil floras, that we are still in the glacial period so far as abnormal climatic extremes are concerned. As resurveys of districts covered by the earlier geological maps are continually in progress, no small amount of the annual contributions to geological literature is devoted to corrections and additions. Thus Dr. T. W. Vaughan notes the discovery of a lower horizon of the Miocene at Porter's Landing, Ga., than has hitherto been known south of Virginia. L. F. Noble describes in detail the geology of the pre-Cambrian formations of the Grand Cañon of the Colorado (American Journal of Science, XXIX). A remarkable feature in the section is an intrusive sheet or sill of diabase from 650 to 950 feet thick. R. W. Stone and W. R. Calvert (Economic Geology, V) find that the so-called Livingston formation of Montana is composed of local volcanic accumulations varying in age from lower Colorado to Fort Union Times inclusive. Prof. H. S. Williams discusses (Bulletin of the Geological Society of America, XX) the age of the Gaspé sandstones, the fossils of which rock comprise species elsewhere occurring at such separate horizons as the Oriskany and the Hamilton. Numerous minor contributions to local geological formations have appeared in current numbers of the Bulletin of the Geological Society of America. Much geological structure and stratigraphy is described in reports mainly of an economic purport, as in the case of a report by H. S. Gale on the Coal Fields of Colorado and Northeastern Utah (Bulletin 415, United States Geological Survey). No small amount of work of a preliminary character is also to be found in the water-supply papers of the United States Geological Survey, the geological conditions which control the distribution of underground water being at present a matter of special investigation by the national and several state surveys. A useful summary of the formational and structural geology of the State of California is presented by Prof. James P. Smith in the Journal of Geology, XVIII. Prof. A. C. Lane adds a second chapter to a matter of like import taken up by him for the State of Michigan in the same journal. Among the most perplexing stratigraphic problems of the continent is the question of the age and true relations of a group of deposits in Kansas on the border between the Paleozoic and Mesozoic sections. Prof. C. S. Prosser discusses the matter at large (Journal of Geology, XVIII) and adheres to the view of the Permian age of the beds in question. The extensive Tertiary deposits of the plains and basins of the eastern Rocky Mountain region with their surprising finds of extinct mammals continue to yield important results. The most important work of a geological character brought out by an American publishing house this year deals with this subject.-The Age of Mammals, by Prof. H. S. Osborne, in which work, the geological structure and the fossil forms are fully illustrated. Among the advances which this work records none is more striking than the better understanding of the geographic conditions under which certain formations formerly regarded as deposited in vast lakes were laid down. In the case of some of the deposits it is now recognized that winds were the chief agency of transportation and deposition, and in other cases streams coursing over plains in front of the newly uplifted mountain ranges. We are thus enabled to picture the region in the past very much as it is now, except that rivers were as in the region of sedimentation laying down gravels, sands, and silts instead of so largely removing them as in the present cycle. The doctrine of uniformity of existing causes, the keynote of Lyell's life work, has been nowhere more patently illustrated than in this western field. Dynamic Geology. In the field of dynamic geology aside from the advances above noted, the journals of the year contain many papers dealing with local studies of structural peculiarities, such as the relations of folds and joints in the quartzites of the Baraboo range (E. Steidtmann, Journal of Geology, XVIII). Some peculiar effects of great pressure are described by W. C. Phalen from the vicinity of Ellijay, Ga., where quartz veins have been squeezed out in detached small stringers looking like pebbles (Journal of Geology, XVIII). Among the novelties of the year should be mentioned the "rock glaciers" or chrystocrenes of the Yukon region, near Dawson, described in two papers by S. R. Capps and J. B. Tyrrell. According to the latter writer these masses of blocks and boulders flowing like glaciers are interstitially filled with ice, the result of the freezing of spring waters, to which circumstance the name chrystocrene has reference. (Journal of Geology, XVIII.) The Glacial Theory.-As for the glacial theory, in advancing which Louis Agassiz made a greater contribution to geology than he knew, it continues to find new applications to long-observed phenomena, particularly in the case of many so-called conglomerates of the closing stages of the Paleozoic era. Following the recognition of the glacial origin of the conglomeratic Permian beds of India, Australia, South frien, and Brazil, and the recent striated stones in the Hu glomerates of Ontario by Pro man, the year witnessed an int in the matter in the United Stat Joseph A. Taff describes ice-bourn boulder deposits of mid-Carboniferous age in the Ouachita Mountain region of southeastern Oklahoma (Bulletin of the American Geological Society, XX), and Robt. W. Sayles and L. LaForge announce (Science, XXXII) the existence of a formation at the top of the Roxbury conglomerate in the Boston area, having the textural characters of an ancient till, including a few finds of striated stones, which the authors believe to be of glacial origin. The possible correlation of this deposit with the well-established glacial epoch of the Permian, adds significance to the investigation and calls for a thorough reëxamination of other conglomerate formations in the light of a possible glacial origin. A notable contribution to the cor ERALOGY CHARLES PALACHE relation of the epochs of ice advance | PETROGRAPHY AND MINand retreat in North America during the Pleistocene period with similar episodes in northwestern Europe is made by Frank Leverett in a German publication (Zeitschrift für Gletscherkunde, IV). As yet these epochs of advance and retreat, or of appearance and disappearance of the Pleistocene ice sheets, is almost entirely based on phenomena exhibited in the Mississippi Valley and the adjacent region; and little or no progress has been made in recent years in extending the subdivisions there recognized into the glaciated area of the eastern United States, though older drift sheets are there recognized at several localities. The usual number of local contributions have appeared during the year in scientific journals regarding the nature and position of such older drift deposits in the interior of the Continent. Petrography. The publication late in 1909 of two works, Igneous Rocks, by J. P. Iddings, in America, and The Natural History of Igneous Rocks, by A. Harker, in England, marks an epoch in the history of this science. They cover substantially the same ground. Both bring to the study of the igneous rocks a wealth of new material and new points of view drawn largely from recent advances in physical chemistry. The laws governing the crystallization of igneous rock magmas are shown to be essentially the same as those controlling ordinary solutions, and the complete elucidation of the former awaits only more detailed knowledge of the behavior of individual minerals under conditions found in rock formation within the earth's crust. The broad views of these authors concerning the nature and relations of rock magmas mark a distinct advance. Significant advances toward adequate knowledge of the rock minerals have been made in America through the studies carried on in the Carnegie Geophysical laboratory by Day and his associates. They have investigated thus far the feldspars, the lime-magnesia pyroxenes, calcium sil The Geological Survey.-The United States Geological Survey continues to be the largest body of active field geologists perhaps in the world. Its publications are numerous and valuable. To meet a certain demand, the geologic folio parts have appeared during the year in book form with infolded maps which are more convenient for transportation in the field than the large atlas sheets. As an example there may be cited the report on the Watkins Glen and Cat-icate, aluminum silicate, and quartz, alonk Folio by Profs. H. S. Williams, R. S. Tarr, and Mr. Kindle (Folio 169). Several state surveys are engaged in field work, many of them in direct coöperation with the national geological survey. The Geological Society.-The Geological Society of America has enrolled in its membership most of the active workers on the continent, and its publications have taken a high rank in the annals of the science; they include each year many contributions of importance in structural and dynamical geology. Several scientific societies contribute directly to the advancement of geological investigation. As an example may be cited the expedition sent to Alaska in 1910 by the National Geographic Society under the charge of Prof. L. A. Martin. employing where necessary pure artificial preparations and working with improved apparatus under conditions permitting exact physical measurements, such as have been nowhere else attained in this class of investigations. These studies have been published during the last four years in the American Journal of Science; and although no addition to the series has been made in the current year except as related to the perfection of instrumental equipment, further results of value may be confidently expected in the future. For most of the substances named there have been made more accurate fusionpoint determinations; the complex changes in crystal structure which some of them undergo at various temperatures have been followed out, and temperature limits for the ex a istence of certain of them established, | cites of that state is noteworthy. giving the first accurate data for the establishment of what may be called "geological thermometer." By means of this scale a more definite conception can be had of the actual temperature existing at the time of formation of certain rocks of common occurrence, such as granite. The researches of Adams into the flow of rocks have shown that it is possible to produce experimental conditions of heat and pressure comparable with those which are active at great depths within the earth; and that under their influence structures due to plastic flow (in the case of marble) may be obtained which are altogether similar to structures characteristic of the metamorphic rocks. (American Journal of Science, xxix, 1910.) The report presents not only very fully illustrated descriptions of a number of remarkable occurrences of calcite, but contains as well a very lucid account of the crystallography of that mineral and a complete list of the multitude of crystal forms thus far discovered upon it. Some interesting deductions are also made upon the relation of certain groups of forms found on these crystals to their geological environment. Tutton has given in his volume on Crystalline Structure and Chemical Constitution a very interesting summary of the results obtained in his investigations, begun some twenty years since, and the subject of frequent papers in the periodical press. Through the invention and construction of various instruments Thus exact experimental results of high precision for the cutting of are gradually taking the place of ap-orientated sections of crystals, and proximate or assumed conditions in the study of rock formation in the earth. The most significant contribution hitherto made to petrography by American students is the Quantitative Classification of Igneous Rocks, promulgated some four years since. This classification, based wholly on chemical composition and a derived theoretical mineralogical composition, has been adversely criticised, especially by English petrographers, although it has been widely adopted in English-speaking countries. Cross, one of the authors of this classification, has written a very able and convincing argument in behalf of its principles, addressed especially to his English critics. He points out the impossibility with present knowledge of making a "natural classification," such as they demand; the confusion in present nomenclature due to lack of a logical principle in present schemes; and the superiority of the new "artificial" classification over those now accepted. (Quarterly Journal of the Geological Society, London, xlvi, 1910.) Mineralogy.-In this science the past year has failed to mark any signal advance comparable with those of recent years. The publication by the New York State Museum of a monograph by Whitlock on the cal for the measurement of their physical and optical properties, he has been able to raise the accuracy of goniometric and optical-constant measurements from a very low level to that of the most refined determination of atomic weights or of such physical measurements as that of the wave length of light. He has also been able for the first time to place the theory of isomorphic replacement, as long ago propounded by Mitscherlich, upon a secure experimental basis. A descriptive work which will prove most acceptable to mineralogists is that of Zambonini upon the minerals of Mt. Vesuvius. We have here for the first time an adequate and comprehensive description of this unique and classic group of minerals. Full study of the great collection of the University of Naples has enabled him not only to give a complete portrayal of a number of species but partially understood before, but also to add several new species to the science. BIBLIOGRAPHY HARKER, Alfred.-The Natural History |