Note 11 — THE NATURE OF THE ENGLACIAL DRIFT OF THE MISSISSIPPI BASIN.
Reading edition
Parts of these tracts were long since described by Bradley of the Illinois Survey. (Geol. Surv. Ill., Vol. IV. p. 227). Collet of the Indiana Survey (An. Rep. 1875, p. 404) and Orton and Hussey of the Ohio Survey (Geol. Surv. Ohio, Vol. III., pp. 412, 414 and 475). The relationship of these tracts to morainic lines and to each other I worked out some years since (Third An. Rep. U. S. G. S. pp. 331, 332, 334) but I owe many details and some important additions to my associate, Mr. Leverett.