Page:Popular Science Monthly Volume 18.djvu/583

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The Abdominal Method of Singing and Breathing as a Cause of Female Weakness. By Clifton E. Wins, M.D. Boston. Pp. 8.

Abridgment of the Nautical Almanac for 1881. By Riggs & Brother, Philadelphia. Pp. 150. 25 cents.

The Geological and Natural History Survey of Minnesota. Eighth Annual Report, for 1879. By N. H. Winchell. Illustrated. St. Paul, 1880. Pp. 183.

Drainage for Health, or Easy Lessons in Sanitary Science. By Joseph Wilson, M.D. Philadelphia: Presley Blakiston. 1881. Pp. 68. $1.

Report of the United States Fish Commissioner for 1878. Washington: Government Printing-Office. 1880. Pp. 988.

Introduction to the Study of Indian Languages. With Words. Phrases, and Sentences to be collected. By J. W. Powell. Washington: Government Printing-Office. With Maps. 1880. Pp. 328.

James Smithson and his Bequest. By William J. Rhees. Washington: Published by the Smithsonian Institution. Illustrated. 1880. Pp. 159.

Sketches and Reminiscences of the Radical Club of Chestnut Street, Boston. Edited by Mrs. John T. Sargent. Boston: J. R. Osgood & Co. 1880. Pp. 418. $2.

The Logic of Christian Evidences. By G. Frederick Wright. Andover: Warren F. Draper. 1880. Pp. 312. $1.50.

Extracts from Chordal's Letter. American Machinists' Publishing Company. New York, 1880. Pp. 320. $1.50.

Elementary Projection Drawing. By S. Edward Warren, C.E. New York: John Wiley & Sons. Twenty-four Plates. 1880. Pp. 162. $1.50.

A Text-Book of Elementary Mechanics. By Edward S. Dana. New York: John Wiley & Sons. 1881. Pp. 291. $1.50.

The Young Folks' Cyclopædia of Persons and Places. Illustrated. By John D, Champlin, Jr. New York: Henry Holt & Co. 1881. Pp. 936. $3.50.



The Age of the Trenton Gravels.—The age of the gravel in which flint implements have been found at Trenton, New Jersey, is carefully discussed by Mr. Henry-Carvill Lewis, in a paper read by him before the Academy of Natural Sciences of Philadelphia. Mr. Lewis divides the surface formations of southeastern Pennsylvania into five clays and four gravels, of which nine deposits the Trenton gravel, as he calls the implement-bearing formation, is, except the recent alluvium, the most recent. At Philadelphia it is called the river-gravel and sand, and contains pebbles which are made exclusively from the rocks forming the upper valley of the Delaware River, and which have the flat shape characteristic of all true river-gravels. It is confined to the immediate vicinity of the river, and has been traced as far up as the Water-Gap. Throughout its whole course it lies within a channel previously excavated through the bowlder-bearing Philadelphia brick-clay and its red gravel, which have been shown to belong to the Champlain epoch. It is therefore later than those formations. The deposit is spread out to its greatest extent at Trenton, where the long, narrow valley of the Delaware, with its precipitous banks and continuous downward slope, opens out into the wide, alluvial plain at a lower level. The fluvia-tile character of this gravel is shown by evidence of various characters, as by the exposures of the "flow-and-plunge structure," in which the layers are seen to dip up-stream, as would be expected to result from the action of downward-flowing water, while the tertiary gravels show in their layers, dipping southeast, evidence of their deposition by incoming oceanic tides. It frequently, also, instead of lying in a flat plain, forms banks with a higher ground close to the present river-channel, and sloping down toward the ancient bank, as often takes place according to the laws of river deposits. The formation can not, however, have been made under the operation of any such flood as has been known within the historical epoch, for no such flood has supplied the amount of water which would be required. It also bears marks of ice-action. It may then be ascribed to a glacier; not to the great glacier of the glacial period, for that glacier at its melting deposited the much older brick-clay and red gravel, but to another more recent glacier whose flood flowed through a channel excavated in the deposits of the first glacial period. This second glacier was much smaller than the first, had its southern extremity confined to the valley, and probably corresponded with the age which European geologists style the Reindeer period. From the fact that the palœoliths found here are similar to the stone implements found among the Esquimaux, Mr. Lewis thinks that they may be the relics of an Esquimau race who once lived in the valley, and he suggests the Esquimau period as a suitable name for their age. Finally, he sums up his conclusions as follows: "1. That the Trenton gravel, the only gravel in which implements occur, is a true river deposit of post-glacial ago, and