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underlying Rock Springs group, which is cretaceous. The strata from which Lesquereux obtained tertiary plants are above this stratigraphical break, by which they are separated from adjacent beds holding cretaceous mollusks. Thus a more careful stratigraphical study has served to harmonize the apparently conflicting evidence of paleontology. The remains of the Dinosaurs of Black Butte are, however, accompanied by tertiary mollusks and plants. -Record, 1874, p. lxx.

Beneath the mesozoic rocks, which include jurassic and triassic strata, are immense thicknesses of paleozoic rocks, including Carboniferous, Devonian, Silurian, and Cambrian, the whole series, from the top of the tertiary to the paleozoic base, having, according to the estimate of Major Powell, a thickness of about 60,000 feet. Beneath all these is a series of crystalline schists, of which about 5000 feet have been measured. The crystalline strata of this region, according to this observer, are every where of great and unknown age.-Record, 1873, p. xlvii.

Professor Marsh has discussed the cenozoic formations of the West, and pointed out the existence of several great basins corresponding to fresh-water lakes of former periods, which are now filled with deposits whose organic remains enable us to assign them to different divisions of tertiary time. The great Green River basin, lying between the Rocky Mountains and the Wahsatch range, has the Uintah Mountains on the south and the Wind River Mountains on the north. Its nearly horizontal strata, with a total thickness of 6000 feet, rest unconformably upon the lignitic or cretaceous coal-bearing strata (often highly inclined), and have yielded the remains of not less than 150 species of eocene age. This region remained dry land during the miocene time, perhaps much longer, but was afterward submerged, and has suffered great erosion. A still larger lake existed in eocene time to the south of the Uintah Mountains, and at a much lower level than the last. South of the Black Hills is a great miocene area, the White River Lake basin, extending from the Rocky Mountains to the 99th meridian, and from the 40th to the 44th parallel. Its strata, which consist of fine materials, have a thickness of about 300 feet, and rest like the preceding on the cretaceous. This area constitutes the

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well-known "bad lands" of that region. Another miocene basin exists in Central Oregon, in great part concealed under more recent basaltic rocks. These strata, which are more or less inclined, and have a thickness of not less than 5000 feet, include in their lower portions a fauna regarded as miocene, but more ancient than that of the White River basin, which is, however, represented in the upper portions of the Oregon basin. Lying in part over the first-named miocene basin was a great pliocene lake, having nearly the same limits as it to the north and west, but with an area about five times as large, and extending eastward and also southward nearly to the Gulf of Mexico. The deposits of this pliocene area, known as the Niobrara basin, attain a thickness of 1500 feet, and contain organic remains which indicate a warm temperate climate, while that of the eocene was tropical, and that of the miocene intermediate between the two. The great erosion which all this region has suffered is well set forth by Dr. Hayden, when he states that from 10,000 to 15,000 feet of strata, from the paleozoic upward, have been removed, leaving only "what may be called remnants behind, occupying restricted areas. The hard and compact limestones of the Silurian and Carboniferous ages are found to a greater or less extent all over the Northwest. They yield much less readily to erosion than the more modern rocks, and are consequently to be found on the summits of the largest mountains 10,000 and 12,000 feet above the sea."

Dr. Newberry, in his lately published volume of the geology of Ohio, has given a full and careful discussion of all the facts known with regard to the superficial geology of the state and the adjacent regions, and has connected them with the hypothesis of land-glaciation. Professor Dana has given his views with regard to the former existence and extent of a great New England glacier.

Mr. George M. Dawson has studied the physical geography and superficial geology of Central Canada between the Rocky Mountains and the great Laurentian axis, which from Lake Superior stretches northwestward to the Arctic Sea. Rising from the lowest plateau of the Red River and Lake Winnipeg, 800 feet above the sea, we have to the west the Great Plains of the middle plateau, 1600 feet above the sea, and the third or western plateau rising to from 2500 to 4000

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feet. Over the latter two are abundant deposits of unstratified drift, which in the middle plateau is almost wholly from the crystalline rocks of the eastern range or Laurentian axis and the limestones adjacent, while on the higher western plateau, though boulders from the latter region still abound, more than one half the drift is from the Rocky Mountains. These themselves afford abundant evidence of glaciers. The author conceives that sub-aerial denudation had already given to the region nearly its present surface before the glacial period. He concludes that the phenomena of the drift in these regions do not require to account for them a polar ice-cap, but are to be explained by the action of local glaciers from the Laurentian axis drifted westward across the submerged prairies toward the Rocky Mountains.

In England the nature and causes of the drift formation have been much discussed. The intercalation of stratified deposits in the unstratified drift, and the presence in both of marine remains, apparently indicate for a part, if not the whole, a submarine origin. In order to conciliate these facts with the hypothesis of a great ice-sheet, Mr. Goodchild has attempted to show that none of the phenomena prove the former agency of the sea, but that all these deposits were formed under land-ice, and in part by the agency of sub-glacial streams, the ice-sheet having excavated from their ocean-bed and pushed up on the land the marine deposits in its onward march. There is, however, a strong reaction from this hypothesis in England [Record, 1874, p. lxxiv.], and several of Goodchild's colleagues in the Geological Survey of the United Kingdom have opposed him in recent papers, notably Hardman, Dakins, and Ward. The latter observes, "The difficulties involved in the theories of Croll, Belt, Goodchild, and others of the same extreme school, certainly press upon me--and I think I may say also upon others of my colleagues -increasingly as the country becomes more and more familiar in its features." He suggests, from the observations of late arctic voyages, that prevailing winds acting upon the surface-ice, rather than currents, are to be taken into account in considering the distribution of drift boulders, and quotes the language of Sedgwick in 1842, who, referring to the transport of granite blocks from the hills of Cumberland to the shores of the German Ocean, says, "No one, I trust, will

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be so bold as to affirm that an uninterrupted glacier could ever have extended from Shap Fells to the coast of Holderness, and borne along the blocks of granite through the whole distance without any help from the floating power of water. The supposition involves difficulties tenfold greater than are implied in the phenomena it pretends to account for. The glaciers descending from the Alps have an enormous transporting power, but there is no such transporting power in a great sheet of ice expanding over a country without mountains and nearly at a dead level."

Campbell, the author of "Frost and Fire," who has devoted, he tells us, thirty-three years to the study of glacial phenomena in both continents, and long held the hypothesis of Agassiz, believing that all Northern Europe had been buried beneath an ice-cap, has been led by further studies in Russia and in North America to reject this view, and declares that from the Caucasus to the Rocky Mountains he sees no evidence of an ice-cap. He adds concisely that "the glacial traces in North America seem to indicate the transfer of oceans with their systems of circulation from one part of the world to another by the elevation and depression of the land."

Kinahan, of the Geological Survey of Ireland, has made known in the western parts of Galway and Mayo a series of crystalline rocks which may be compared with those of our Appalachian belt. They consist of bedded granites and gneissic and hornblendic strata, quartzites, limestones, micaceous and talcose schists, serpentines, steatites, etc., and are divided by the author into three groups, the united thickness of which is estimated at over 10,000 feet. They are wholly without fossils, and are penetrated by granitic and other intrusive rocks. Being overlaid by fossiliferous strata of Silurian (Llandovery) age, it is conjectured by Kinahan that they may be altered Cambro-Silurian rocks. The similar crystalline schists of Donegal, as long since pointed out by the writer, are partly Huronian and partly Montalban. The hasty generalizations and misinterpretations through which in so many regions geologists have incorrectly referred crystalline strata like these to paleozoic or more recent times [Record, 1872, p. xxxvii.], have recently received a further illustration in Carinthia, where, on the authority

of Suess, the mica-schists and the granites of Casauna and the Gailthal have been described as Carboniferous, and supposed to be even more recent than certain strata undoubtedly of this age. Stache has shown that, besides the Carboniferous beds, important masses of fossiliferous Silurian and Cambrian strata are present, and that the crystalline schists of the region really occupy a position unconformably beneath the old paleozoic strata.

The evidence accumulates that the whole Cambrian series in Wales, as originally defined by Sedgwick [Record, 1872, p. xxxvi.], extending upward to the unconformably overlying May Hill sandstone (the equivalent of the Oneida of the New York system), is a single physical series. The stratigraphical breaks supposed by Ramsay to exist in Wales above and below the Tremadoc rocks are not recognized by Hicks in his recent study of the ancient rocks at St. David's. The two most important paleontological breaks are at the top of the Menevian and of the Tremadoc. The Silurian and Cambrian nomenclature is again much discussed in England, and the fact that the Silurian of Murchison has not and never has had any base-line is insisted upon. Some, with Hughes, follow Sedgwick in confining the Silurian to the strata above the May Hill sandstone, and give to the rocks from this horizon to the top of the Tremadoc the name of Upper Cambrian, originally applied by Sedgwick; while a greater number restrict the name of Cambrian to the strata below the last-named horizon, and give the name of Cambro-Silurian, or that of Lower Silurian, to the Upper Cambrian. Dewalque has investigated the ancient rocks of the Ardennes, in Belgium, and shown that the whole series of the Cambrian from the Harlech to the Tremadoc inclusive, is probably represented in that region.

The researches of J. Arthur Phillips on the metalliferous rocks of Cornwall cover a great variety of important points. He shows, from a large number of chemical analyses and microscopic studies, that the so-called killas are more or less crystalline schists, often containing crystallized magnetite, quartz, chlorite, and hornblende; and points out that, though of very varying composition, they all differ so widely from granite that no reconstruction or alteration of them could ever convert them into this rock, as speculators in geol

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