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2. Changes of level in the region of the Great Lakes in recent geological time; by FRANK B. TAYLOR. (Letter to J. D. Dana.) “ First, as to the probable place of the highest shore line on the north coast of Lake Superior. It seems to me that when we take full account of all that is now known about the highest shore line in the regions adjacent to Lake Superior we are bound to conclude, pending further exploration, that this line probably attains an altitude of at least 1200 to 1300 feet above sea level in the Nipigon region at the north-northwestern extremity of the lake, and at least 1100 to 1200 feet on the northeastern side at Lake Missinaibi. The facts upon which this opinion rests are as follows: The altitude of the Herman beach of “Lake Agassiz” (ancient Gulf of Winnipeg) is 1055 feet at Lake Traverse, and 1220 feet at the international boundary. On the east side of Red river in Minnesota this beach rises a little more rapidly. On the southeast side of Beltrami island in northeastern Minnesota it occurs at 1087 feet and on the northwest side at 1195 feet. At Duluth, 1134 feet, and at Mt. Josephine on the northwest coast of Lake Superior, 1207 feet. Near L'Anse and again near Marquette on the south coast, 1190 feet. Near Sault Ste. Marie 1014 feet. Near Cartier, Ontario, about 1200 feet, and at the ancient Nipissing strait at North Bay, Ontario, 1140 feet on the north and more than 1220 feet on the south side.

It is noticeable that the lowest level of the line in this list is at Sault Ste. Marie. If the highest shore line passes downward to the north from this place, or even on a level, it must cut off the supposed straits to the north of Lake Superior. But considering the high altitude of the shore line in all the regions bordering the lake, Green Bay only excepted, the chance of this seems extremely small. The highest beach, rising northward from 1134 feet at Duluth to 1207 feet on Mt. Josephine, (supposing Lawson's observations at the latter place to be correct) must meet the beach which passes northward from Sault Ste. Marie somewhere in the north, because they are the margin of one water plane. It seems almost certain, therefore, that the highest beach must rise more rapidly northward from Sault Sie. Marie than it does from Duluth. For it starts from a level about 120 feet lower. I am bound to conclude, therefore, for the present that the highest shore line rises at least 2 feet per mile north ward from Sault Ste. Marie and keeps well up along the north shore, leaving the open straits to the north, as stated in my paper. (As I remember Prof. Lawson's figures, the Missipaibi pass is about 1044 feet above sea level and the Kenogami pass 1109 feet.) I see no escape from this conclusion, then, unless it be by some abrupt and very exceptional dip of the ancient water plane downward to the north. It would appear, therefore, that the mean height of the highest shore line in the Superior basin can hardly be less than 1100 feet or more than 1200. On present data the most probable mean that I can name for the whole basin is about 1150 feet. I think this estimate is conservative and likely to prove too low rather than too bigh.

Second. As to the origin of the highest beach, I believe that it was all made at sea level and that the Iroquois beach in the Ontario basin, the highest beach in the northern parts of the Huron and Michigan basins with that of the Superior basin, and also the upper beach of the Red river and Winnipeg basin, are all one continuous beach and of the same age in all parts. In the Michigan and Huron basins this beach slopes downward toward the south and passes under the present lake level, thus leaving Lake Erie with all its beaches and also the Chicago outlet entirely above that plane. The Erie beaches are undoubtedly the shores of an ice-dammed lake of the glacial recession. It was much the largest lake produced in this way. But there were other smaller, shorter lived ones at the south ends or sides of all the basins. The Ontario basin was probably also partly filled by a large temporary lake of this kind, emptying through the Mohawk valley. But the record it may have left has been wiped out by the later marine invasion which made the Iroquois beach.

Third. As to the relations of Niagara, Lake Erie, etc., I have the data to show conclusively that the present period of the great cataract's activity began at a point a few rods above the cantilever railroad bridge. Before that time the outlet of the upper lakes was eastward over Nipissing pass and down the Ottawa river, and greater Niagara was replaced for a long period of time by a very much smaller stream (the “Erigan” river), which drained only the Erie basin and possibly not all of that. This smaller stream made the narrower, more shallow gorge of the whirlpool rapids, extending from Foster's flat below the whirlpool up to the cantilever bridge. The time which was required to do this must have been many times longer than Mr. Gilbert's estimate of the age of the whole gorge from Lewiston up. I should say that the multiplier would have to be tens rather than units. As a measure of the duration of postglacial time, therefore, I do not see how the gorge can have any value worth mentioning. But without meeting this demand, it goes far enough to show that postglacial time must have been much longer than the current estimate.

But to go a step farther, there is considerable evidence to show that the greater Niagara had another earlier period of postglacial activity, during which it cut out the gorge from Lewiston to Foster's flat. Overhanging Foster's flat is the old fall ledge of the greater cataract with the narrower gorge of the smaller stream cut back on the south side. At this old ledge the great cataract ceased for a long period of time, and when it returned the smaller stream had cut back in the interval to the cantilever bridge. Thus the great cataract bas been intermittent in its activity. It has had two active periods separated by the long, almost indefinitely long, period during which the falls of the smaller stream carried on the work. And all this plus a short period for the Chicago outlet has been since the ice age. There is some evidence in the beaches of the north pointing to this earlier period of the cataract. But this episode of the gorge is not yet so strongly established as the other two.

Fourth. A word as to the nature of the changes that have produced these great alterations of land altitude. They are so extensive, so great, and above all so recent as to be almost appalling when one thinks of them.

Of the whole amount of apparent elevation along the line of the parallel of 46° 30', which passes close to Duluth, Sault Ste. Marie and North Bay, I think I can make out fairly well that between 600 and 800 feet of it are due to a change of the secular kind, while the rest is of the paroxysmal sort, I have always embodied this distinction (which is derived from Dana's Manual of Geology) in my working hypothesis, and with good effect. I am quite sure that it was the secular factor that changed the outlet of the upper lakes this last time and brought Niagara into its present state of activity-in consequence of a secular relative, differential, northward elevation. It seems probable that the earlier episode of Niagara was also due to the same factor. But the order of relative change was probably then in the opposite direction. I believe that maximum northern relative elevation coincided with maximum glaciation, as you have said. But I believe, further, that maximum relative northern submergence coincided with the climax of the postglacial warm epoch now passing off. Relative northward elevation has been in progress for some time past and we are now advancing again toward a climax of cold.”

3. Introduction to Geology as historical science. Einleitung in die Geologie als historische Wissenschaft. Beobachtungen über die Bildung der Gesteine und ihren organischen Einschlüsse. I Theil: Bionomie des Meeres. II Theil: Die Lebensweise der Meerestbiere. III Theil : Lithogenesis der Gegenwart (by Johannes Walther), pp. i-xxx and 1055. (Gustav Fischer), Jena, 1893-1894,—The author describes the method employed in this “Introduction to Geology" as the ontological method of investigation, which consists in the interpretation of the events of the past by the phenomena of the present. The aim he has held before him while constructing this elaborate work has been to bring together from many sources, from periodicals, monographs and special treatises, all the facts bearing upon the general question of the formation of rocks and upon the conditions under which organisms have lived and died and been fossilized.

The work is divided into three parts: The first (Bionomie des Meeres), on the marine conditions of life, was briefly noted when it first appeared in 1893.* It is an elaborate description and classification of the zones of life-habitat of the ocean following the system of classification proposed by Haeckelt and gives a very convenient and apparently exhaustive synopsis of the facts with full references to sources.

* This Journal, III, vol. xlvi, p. 240. + Planktonstudien, Jena, 1890.

The second part (Die Lebensweise der Meerestbiere, pp. 197–532) treats of the mode of life of sea animals. In its 335 pages are brought together the facts known about the geographical distribution, bathymetric range and other conditions of adjustment to conditions of life environment of the organisms whose remains could be preserved as fossils. The facts are classified in sections for each of the larger groups of organisms, the classes or branches. Here also references to original sources are liberally given.

The third part (Lithogenesis der Gegenwart, pp. 535-1055) describes the methods of formation of rocks on the present surface of the earth. The first section is devoted to the statistics of Lithogeny or dynamical geology, classified under the heads of Weathering, Ablation, Transportation, Corrosion, Deposition, Diagenesis and Metamorphism. The second section describes and classifies the various areas of the present surface of the earth, (Du Faciesbezirke der Gegenwart) distinguished by differences of climate or physical surface as affecting the geological formations or phenomena. In the last section the outlines of a comparative Lithology are discussed under such headings as the correlation of facies, the equivalency of rocks, changes of facies.

Although there is little original in the book, a large amount of statistics scattered over a very wide range of literature are brought together, concisely stated and classified in such a way as to be helpful and suggestive to the geological student, to which end the full references to original sources and the good indexes at the close contribute no small share.

H. S. W. 4. Alabama, Geological Survey-Geological Map of Alabama with explanatory Chart. E. A. Smith, State Geologist and Assistant. Two large folio sheets. 1894.–The map presents in clear and yet not too strong colors the geological features of the State, with division of the scale as fine as the classification in the reports. The Chart presents an admirable synopsis of the important features of the geological conditions of the State. In the first column names, synonyms, classification and common fossils are given for each of the recognized formations, opposite each division in the second columu are given thickness, lithological and topographical characters, area and distribution, in a third column, useful products followed by a fourth describing the soils, characteristic timber growth and agricultural features, and a final column in which are listed the Reports in which each of the formations is described, making a convenient index to the geology of the State for the general reader as well as the geologist.

5. Manual of Geology ; by JAMES D. DANA.—The new (fourth) edition of this work, entirely rewritten and much enlarged, will be ready about the middle of January.

6. Bulletin of the Department of Geology, University of California, A. C. Lawson, Editor, Berkeley, Cal.—This work bas been noticed in this Journal, vol. xlvii; p. 147, 1894, and we are now in receipt of Nos. 5, 6 and 7.

No. 5. The Lherzolite-Serpentine and associated rocks of the

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Potrero San Francisco; by Chas. PALACUE.—This presents the results of a study of this rock both in the field and in tbe laboratory. The facts obtained show that it is the result of alteration of a very basic igneous rock intruded into the San Francisco sandstone.

No. 6. On a rock from the vicinity of San Francisco contain: ing a nero Soda-Amphibole ; by the same author.–The rock consists of fine grains of albite. Through this is thickly sprinkled the amphibole in small acicular crystals, in simple forms. The optical relations determined in thin section are b=b, c:a = 11° -13° in front: Pleochroism strong: a=sky-blue to dark blue, b=violet, (=yellowish browo to greenish yellow. Absorption a b>c. Is often zonally built. A chemical analysis gave the following results :

Sio, A1,0, FeO, FeO MnO MgO Cao Na, K,O H,0 Sum. 55:02 4 75 10:91 9:46 tr. 9:30 2:38 7 62 0127 ? = 99 70

A consideration of the molecular ratios of the oxides from this analysis shows them to be SiO :918 Feo •131)

Na,0 Ai,, .046 114 Mgo

.123.196 Feg03

K,0 .003 , 126 .008 Cao 043 )

" whence (Na, K)20: R203: Si0, ::.126: 114: 480 :: 1:05:0.95 : 4 and RO: Si0, : : :407::437::1:1. From which it appears that the mineral is a mixture of the actinolite (Ca, Mg, Fe)SiO,, the glaucophane NaAl(Si0,)and the riebeckite NaFe(Si0,), molecules. The author proposes for it the name crossite after Mr. Whitman Cross of Washington.

The propriety of giving new names to indefinite mixtures of isomorphous molecules is at best a very doubtful one, unless from constancy and frequence of occurrence there is a positive demand for such a term. By far the larger part of the work of chemical mineralogy in the last few decades has been ridding the terminology of just such synonyms; and one needs only to glance at the index to the recent edition of Dana's Mineralogy to become convinced of this fact. The best usage seems to require that definite mineral molecules once established should receive definite names, and isomorphous mixtures should be classed under the one prevailing.

No. 7. Geology of Angel Island ; by F. L. RANSOME.—This is a very careful and excellent study of the geology and petrography of a small island in San Francisco bay. The island consists in the main of the San Francisco sandstone which is folded, and intruded with serpentine and a basic igneous rock classed by the author under fourchite. It is accompanied by a detailed geological map and plates, and Dr. G. II. HINDE adds a chapter on the idiolarian chert found on the island.

L. V. P. 7. Mineral Resources of the United States. Vol. IX. Calendar Year, 1892, 850 pp. Washington, 1893. Vol. X. Calendar Year, 1893, 810 pp. Washington, 1894. David T. Day, Chief of Division of Mining Statistics and Technology (U. S. Geol.

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