The life of the Pleistocene or glacial period; as recorded in the deposits laid down by the great ice sheets

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 Excerpt: ... bones of small animals 5 feet Northeastern drift containing many decomposed boulders 2 feet Shale 7 Those species marked with an were included in Todds list, where, however, Physa intcgra is identified as Physa hcterostropha. "Calvin, Bull. Geol. Soc. Amer., XXII, pp. 211-212. "Bull. No. 158, U. S. Geol. Surv., p. 85. Bull. Geol. Soc. Amer., XXIV, p. 546,1913. 7. Minnesota It is not definitely known how far north the Aftonian deposits extend, but it is believed that they are represented in the southern part of Minnesota. Chamberlin81 has correlated with the Aftonian certain peaty deposits in the basin of Lake Agassiz, together with other peat beds between the two till sheets in southern Minnesota, described by Winchell. At this time, however, the pre-Kansan or Nebraskan till sheet was but little known, and the Aftonian was placed above the Kansan. The recognition of the Aftonian as an interval between the Kansan and the Nebraskan, places some of these deposits from Minnesota alxve the Kansan, and hence correlates them with the Yarmouth Interglacial stage. A number of Minnesota records, however, appear to be referable to the Aftonian interval. In Wilkin County,82 at Mitchell, a well record gave the following section: Soil 2 feet. Yellowish-gray till 6" Gray sand yt" Dark bluish till 18" Sandy black mud x" The sandy black mud contained many small gastropod shells. The dark blue till is evidently Kansan and the shells are referable therefore to the Aftonian interval. In McLeod County, a number of wells encountered mollusks at various depths.83 A boring from the Stewart railroad well descended to a considerable depth, as noted below: Yellowish till 20 feet Dark bluish till 240 feet Sand with gravel 5 feet Height of section 265 fee...