ILSTRAT Highlights Almost 200 Years of Science, 500 Million Years of History Now freed from the book shelf, the collected knowledge of Illinois' geologic past has been digitized, and released online as ILSTRAT – an interactive resource for the public, industry, and government to understand the rocks beneath our feet. Organized as an editable online database, or wiki, ILSTRAT brings to life the best scientific consensus of how Illinois was built ‚Äì from the ground down.