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Basalt fiber is made from a single material, crushed basalt, from a carefully chosen quarry source. [1] Basalt of high acidity (over 46% silica content [2]) and low iron content is considered desirable for fiber production. [3] Unlike with other composites, such as glass fiber, essentially no materials are added during its production.
Ordovician rocks in Illinois are divided into three series, each separated by an unconformity; from oldest to youngest, these are the Canadian, Champlainian, and Cincinnatian series. Ordovician features in Illinois include the now-buried Glasford Structure in Peoria County , a crater caused by a meteorite impact roughly 455 million years ago.
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A map showing approximate areas of various Mississippian and related cultures. The Koster Site is located near the center of this map in the upper part of the Middle Mississippi area. The Koster Site is a prehistoric archaeological site located south of Eldred, Illinois. The site covers more than 3 acres and extends 30 feet down into the ...
Basalt frequently breaks into octagonal and pentagonal columns, creating a unique "postpile" appearance. Extensive slopes made of fractured basalt talus are visible at the base of many of the cliffs along the Metacomet Ridge. [6] The basalt floods of lava that now form much of the Metacomet Ridge took place over a span of 20 million years.
The Dickson Mounds Museum is a museum erected on the site in 1972 by the U.S. state of Illinois; it describes the life cycles and culture of Native Americans living in the Illinois River valley over a period of 12,000 years since the last ice age. The museum is part of the Illinois State Museum system. [5]
During cold spells Illinois was home to animals like mammoths, mastodons, stag mooses, and giant beavers. Snowshoe hares also used to make their home in Illinois. [20] The Illinoian (stage) glaciation occurred some 300,000 to 130,000 years ago. The last time glaciers covered Illinois was during the Wisconsin glaciation 25,000 years ago. [18]
The Illinois Salines, also known as the Saline Springs or Great Salt Springs, is a salt spring site located along the Saline River in Gallatin County, Illinois.The site was a source of salt for Illinois' prehistoric settlers and is now an archaeological site with a large quantity of organic remains.