Geology topics
Research about Illinois
Source-linked reports with geographic coverage including Illinois.
Aeromagnetic map of northeastern Illinois and its geologic interpretation
No abstract available.
Canada geese of the Mississippi flyway with special reference to an Illinois flock
This Canada goose study is based on data from three primary sources : data collected at Horseshoe Lake, Alexander County, Illinois ; surveys by the authors on the distribution, habitat, and behavior of the population elsewhere in the Mississippi flyway ; and banding records of the Jack Miner Bird Sanctuary, Kingsville, Ontario. Data from other sources have been used as indicated in the text.
Origin of the bedding replacement deposits of fluorspar in the Illinois field
The banded fluorspar deposits of the Cave In Rock district are attributed to replacement of limestone and the preservation of bedding and cross-bedding of the rock. The solutions contained hydrofluoric acid which reacted with CaCO 3 . The replacement was stoichiometrical, with consequent reduction of volume, but continued deposition of calcium fluoride, brought in from other points, partly or completely filled the voids. Thus, the pure bands display a comb structure, and represent replacement of pure limestone laminae. The less pure granular bands, devoid of comb structure, reflect the alternating, impure bands of the rock in which the fine-grained impurities (ferriferous carbonate, clay, et al) were disseminated. Recrystallization of clastic quartz grains in some calcareous sandstone layers resulted in the formation of bands of quartz grains. The writer dissents from the views of Bastin who believes the banding is due to rhythmic precipitation. Chemistry and controlling structural conditions are discussed.
Belleville-Breese folio, Illinois
The Belleville and Breese quadrangles are bounded by meridians 89° 30' and 90° and parallels 38° 30' and 38° 45' and thus include one-eight of a square degree of the earth's surface, an area, in that latitude, of 466.56 square miles. They lie in southwestern Illinois (see fig. 1), a few miles directly east of St. Louis, and comprise considerable portions of Clinton, Madison, and St. Clair counties, and a small part of Bond County. Belleville, from which the Belleville quadrangle is named, is in the southwest corner of the area.