Geologic Samples Library Collections

For 100 years the Illinois State Geological Survey has been collecting drilling cuttings in an effort to help its scientists and the public understand the subsurface geology of Illinois. These collections, now housed in the Geologic Samples Library (GSL), contain approximately 70,000 sets of well cuttings (rock brought to the surface during drilling) and over 15,000 rock cores (cylindrical rock samples).

The cuttings come mostly from oil and water wells; the cores come primarily from coal, oil, stratigraphic and mineral tests, engineering studies, and foundation and bridge borings. Most of the core on file was condensed from its original form, although in the last 25 years saving continuous core sets has been emphasized. The Library also houses collections from mines, quarries, outcrops, clay pits, sand and gravel deposits, and Pleistocene glacial deposits.

These collections are valuable records of the approximately 1.5 billion year-old geologic history of Illinois. Billions of dollars have been expended, mostly by private companies, in the infrastructure required to collect these samples. Having these samples available allows Survey geologists and others to access this valuable information without the expense of reacquiring the samples, which in a great many cases would be impossible because the sites are no longer accessible.

Search GSL collections by location
ILOIL
ILWATER