Page:Origin of the High Terrace Deposits of the Monongahela River.pdf/1

368 all of the divisional lines that have been selected by different authors for different localities can and ought to be recognized. There should even be added one or two more in order to express more nearly the true relations of the strata of the two series to each other. Such a classification will be the subject of the next paper.

ORIGIN OF THE HIGH TERRACE DEPOSITS OF THE MONONGAHELA RIVER.

By, Morgantown, W. Va.

At the Minneapolis meeting of the A. A. A. S., in 1883, the writer presented a paper before Section E in explanation of the terrace deposits along the Monongahela river, as well as those along the old and abandoned Teazes valley, which extends from the Great Kanawha at St. Albans, along the C. & O. R. R. to the Ohio river at Guyandotte.

In that paper the origin of these deposits was referred to the hypothetical glacial dam in the region of Cincinnati, evidence for the existence of which had just then been published by Prof. G. F. Wright, of Oberlin, Ohio.

Continued studies of the river between the Great Kanawha and the Monongahela have still led the writer to refer the terrace deposits of the latter river to a glacial dam, but not to the one which Prof. Wright believes existed at Cincinnati.

It is now pretty surely established, through the work of Carll, Spencer, Hice, Foshay, Chamberlin, Leverett, and others, that the Monongahela, lower Allegheny, and upper Ohio waters drained northward into the lake Erie basin in pre-glacial time. The great ice-field which covered northern Ohio and Pennsylvania, and descended southward nearly to the Ohio river at Rochester, or Beaver, Pa., would, of course, effectually stop the northward drainage of this pre-glacial river, and impound the accumulating water into a vast lake-like reservoir, until it filled up to the level of any divides that might lead the surplus water across them to other drainage channels.

If any such old outlets exist, they would furnish almost a demonstration of the reality of this supposed glacial lake,