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Aftonian belt benches Big Sioux bowlders Boyer river brown brownish Buena Vista county buff calcareous Carroll county Cherokee county Clay county creek valley Dickinson county dissected drainage east erosion exposed exposures farther Gillett Grove glacial gravel deposits gravel hills gray gumbo Ida county Illinoian Iowa Geol Iowa Geological Survey Iowan area Iowan drift area Iowan ice Kansan drift layers leached loess limestone pebbles line of section Little Sioux river Little Sioux valley lobe loess loesslike clay Lyon county mapped material miles Moines Nebraskan noncalcareous northeast quarter northwest northwestern Iowa O'Brien county Ocheyedan Osceola county outwash overlain overlying oxidized places plain post-Kansan quarter of section railway region ridge Rock Sac county sand and gravel shows slope soil southeast southern southward southwest quarter stream surface terminal moraine terrace thickness topography township tributary unleached upland upper valley gravels western Wisconsin boundary Wisconsin drift yellow zone
Page 6 - Survey continued to cooperate with the Water Resources Branch of the United States Geological Survey in the work of stream gaging and discharge measurements of the important streams of the state.
Page 164 - Illinoian till was deposited at a time considerably before this epoch of loess deposition, and (3) that the Kansan drift was deposited considerably earlier than the Illinoian till and much earlier than the loess was formed, or in other words, this line of evidence also supports the view that the Iowan stage of glaciation was distinct from, and later than, either the Kansan or Illinoian stages of glaciation.
Page 170 - From these various observations it is evident that the Illinoian drift has been modified much more by weathering and erosion than has the lowan. It also appears that most of the modification of the Illinoian occurred prior to the formation of the main deposit of loess. It seems clear therefore that the lowan drift is entirely distinct from and considerably younger than the Illinoian drift.
Page 137 - Decayed pebbles and whole ironstone concretions are comparativelv few, though there are numerous fragments of ironstone concretions, as if these had been derived from such older gravel-bodies as the Buchanan. The amount of solution which the limestone pebbles have suffered is considerable. This varies according to the coarseness of the material. Fine sandy gravel commonly contains no limestone pebbles in the upper ten to twelve feet, whereas in coarser materials calcareous constituents have been...
Page 57 - Leverett) (including super-Kansan "gumbo," or "gumbotil" of Kay2) at top of the Kansan drift; also Buchanan gravel (of Iowa geologists) beneath Iowan drift and loess 3. Kansan drift (of Iowa geologists) 2. Aftonian gravels, vegetal deposits, soil and weathered zone (of Chamberlin) (including super-Nebraskan "gumbo" or "gumbotil" of Kay) at top of Nebraskan drift 1. Nebraskan drift (of Iowa geologists) (pre-Kansan or subAftonian of Chamberlin...
Page 171 - On its melting the Recent epoch was inaugurated. The consideration of the various lines of evidence reviewed in this paper leads the writers to the conclusion stated in the Introduction, that there is warrant for the continued use of lowan drift and lowan stage of glaciation as major subdivisions of the Pleistocene classification. CHAPTER IX BORDER PHENOMENA AND LIMITS OF THE IOWAN DRIFT. , It seems necessary to make some statement concerning the definition of the limits of the lowan drift.
Page 364 - Holman township, and 6 miles south in the southwest quarter of section 5 and the southeast quarter of section 6 of Oilman township. In the hill in southwest 5, Oilman township, a pit exposure showed about three feet of coarse ferruginous gravel resting upon fresher finer-grained material. Clay-balls are very abundant, amounting to 25 per cent of the total contents in one analysis, and on the pit face one was exposed for each square inch of surface.
Page 218 - ... gumbotil" be used. Gumbotil is, therefore, a gray to dark-colored, thoroughly leached, non-laminated, deoxidized clay, very sticky and breaking with a starchlike fracture when wet, very hard and tenacious when dry, and which is, chiefly, the result of weathering of drift., The name is intended to suggest the nature of the material and its origin, and it is thought best to use a simple rather than a compound word.
Page 138 - Iowan area, and especially in Buchanan county near Independence, there are low rounded knolls on the upland which apparently belong to an older deposit. These knolls contain highly oxidized and decayed ferruginous gravels, with an abundance of ironstone concretions and disintegrated granites, greenstones, and other igneous rocks.
Page 211 - The till is noncalcareous over the gravel but becomes calcareous downward between the two deposits at a depth of eight or nine feet from the top. The relations shown in the cut suggest overriding of a deposit of sand and gravel by a readvance of the ice but afford no good evidence of a post-Kansan till deposit. Only parts of the county along and near the Waterloo, Cedar Falls & Northern railway, the Chicago, Milwaukee & St. Paul railway, and the Chicago & North Western railway were examined in 1914....