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Migmatite is a gneiss consisting of two or more distinct rock types, one of which has the appearance of an ordinary gneiss (the mesosome), and another of which has the appearance of an intrusive rock such pegmatite, aplite, or granite the (leucosome). The rock may also contain a melanosome of mafic rock complementary to the leucosome. [11]
[3] Landmark name Image Location County Culture Comments; 1: Albany Mounds Site: Albany: Albany Mounds Trail 4]: Whiteside: Middle Woodland: Hopewell: 2: Alton Military Prison Site: Alton: inside the block bounded by Broadway and William, 4th, and Mill Sts. 5]: Madison: Euro-American: 3: Apple River Fort Site: Elizabeth: 0.25 miles east-southeast of the junction of Myrtle and Illinois Sts. 6 ...
In 1795 James Hutton made some of the earliest comments on the relationship between gneiss and granite: “If granite be truly stratified, and those strata connected with the other strata of the earth, it can have no claim to originality; and the idea of primitive mountains, of late so much employed by natural philosophers, must vanish, in a ...
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.
^ Since 1983, Massachusetts has had 3 other official state rocks: State Historical Rock (Plymouth Rock), State Explorer Rock (Dighton Rock), and State Building and Monument Stone . In 2008, a State Glacial Rock (Rolling Rock) was designated as well. [82] ^ A measure passed the Oregon Senate in March 1965 naming the thunderegg as Oregon's state ...
Migmatite featuring felsic minerals, at Morton Gneiss Complex. Granitization is an old, and largely discounted, hypothesis that granite is formed in place through extreme metasomatism. The idea behind granitization was that fluids would supposedly bring in elements such as potassium, and remove others, such as calcium, to transform a ...
The rock record contains an uncertain age gap with younger 1.8 billion years old Proterozoic quartzofeldspathic and migmatite gneiss, with amphibolite and biotite schist. Around 1.9 billion years ago, mafic, intermediate and felsic rocks, in some cases with subordinate metasedimentary rocks, began to form and metamorphosed, reaching greenschist ...
Paleontology has a long history in the State of Illinois, stretching at least as far back as the 1850s, when the first Mazon Creek fossils were being found. Early in the ensuing 20th century a Silurian age fossil reef system was discovered in the state.