Geology . derlying formations, and especially the neighbor-ing formations in the direction whence the ice came, are weak. The miliar that it is unnecessary to give extended references to the literature of the sub-ject. They were emphasized in many of the early publications concerning the drift,The striae and other scorings of the ice. are elaborated in the 5th Ann. Kept. U. SGeol. Surv. The study of the drift from the standpoint of genesis is given in theJour of Geol.: Vol. II, pp. 708-724, and 837 851, and Vol. Ill, pp. 70-97, and inGlacial Geology of New Jersey, pp. 3-33. The geological repo
Geology . derlying formations, and especially the neighbor-ing formations in the direction whence the ice came, are weak. The miliar that it is unnecessary to give extended references to the literature of the sub-ject. They were emphasized in many of the early publications concerning the drift,The striae and other scorings of the ice. are elaborated in the 5th Ann. Kept. U. SGeol. Surv. The study of the drift from the standpoint of genesis is given in theJour of Geol.: Vol. II, pp. 708-724, and 837 851, and Vol. Ill, pp. 70-97, and inGlacial Geology of New Jersey, pp. 3-33. The geological reports of all the statesaffected and of Canada contain descriptions of the phenomena. THE PLEISTOCENE OR GLACIAL PERIOD. 339 fine material of the drift is made up, in large part, of the same mate-rials as the gravel and bowlders, but of these materials in a finerstate of subdivision, and often in different proportions. The coarsematerials and the fine are often mixed without trace of assortmentor Fig. 473.—A section of unstratified drift—till or bowlder clay, on bed-rock. Newark, N. J. The drift of any locality is likely to contain rock material fromevery formation over which the ice which reached that locality hadpassed; but the larger part of the drift of any place is composed ofmaterials derived from formations near at hand. Probably 75% ofthe material of the drift has on the average not been moved 50 No agent except glacial ice can impress these precise features on 1 The Local Origin of the Drift, Jour, of Geol., Vol. YTII, p. 426. 340 GEOLOGY. the deposits which it makes, and these are, on the other hand, pre-cisely the features which existing glaciers are now impressing on their deposits. (2) The bowlders and other stones of the drift.—The bowldersand smaller stones of the nnst ratified drift possess significant,features. Many of them have smooth surfaces, but they are not
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