Fossil Story

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  • Topic: Illinois, Ordovician, Illinois River
  • Pages : 3 (1092 words )
  • Download(s) : 99
  • Published : May 13, 2013
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Fossil Story Paper
Northeastern Illinois has a great deal of geological history hidden beneath the surface. If you just take a trip to the Larson Quarry or even Pit 11 you can find some interesting rock formations as well as fossils in them. But, if you cannot get to these areas, this paper can tell you what you can find in 5 different locations in Northeastern Illinois. We will be looking at Larson Quarry, Thornton Quarry, Mazon River, Pit 11, and the Glacial Drift which is at Palos Hills and throughout the surface of the Chicago area).

The first stop is the Larson Quarry. This is located near DeKalb, Illinois. The specific coordinates are 42˚N, 88˚ 35’ W at 920 feet. This site contains specimens from 450 million years ago which include trilobites like Flexicalymene, brachiopods like platystropia, rafnesquina, leptaena, the horn coral streptelasma, an unnamed bivalve, bryozoans, various crinoid stem parts, the cephalopod endoceras, and the gastropods cyclonema and malcurites. The rock types and formations that were found around these fossils were Cincinnatian Maquoketa Shale and Galena Dolomite. “The Maquoketa shale, which contains seams of argillaceous dolomite…and ranges from highly to slightly weathered, with the highly weathered portions having the consistency of a stiff clay and are extremely fissile” (Preber). These fossils were preserved by replacement as well as mold and cast.

The Mazon River, which is near Morris, Illinois is located at 41˚ 20’N, 88˚ 30’W at 525 feet. This site had fossils from 290 million years ago and included seed ferns like alethopteris and neuropteris, true fern Pecopteris, horsetail rush parts calamites (trunk), and annularia (leaf whorl), lycopod tree (club moss) parts and bark lepidodendron, and leaf lepidophylites. The rock types were shale and sandstone as well as coal and the formation was Francis Creek. The Illinois State Museum writes in an article about how Francis Creek formation is formed: “Much of the area that...
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