Please Note: The McCracken Core Library and Research Center is open by appointment during normal working hours. If you have any questions, would like to visit the facility or examine the library holdings, please contact us.
We provide examination and sampling of subsurface geologic materials for research purposes to interested individuals, businesses and organizations at the discretion of the state geologist. To request core or cutting samples, reference the following policy and procedures and sample request form.
Data, Forms and Publications
- Well Logs, Rock Cuttings and Cores
- Well Drilling Logs Viewer – Access well logs and related data using this ArcGIS application
- Core Library Core and Cuttings Holdings List (September 2019)
- Policy and Procedures - PUB2946
- Rock sample Request MO 780-2220
- McCracken Core Library and Research Center - Missouri Resources magazine article
- Celebrating 30 years; McCracken Core Library and Research Center - Phelps County Focus newspaper article
Locate information about about core and cuttings holdings at McCracken on a map using online Geosciences Technical Resource Assessment Tool, GeoSTRAT.
The McCracken Core Library and Research Center is a repository for nearly 8 million feet of subsurface geological materials (rock core and cuttings). It has core from more than 3,300 drill holes and cuttings from more than 15,000 drill holes from locations across Missouri. The 21,000 square-foot facility is named in honor of geologists Earl and Mary McCracken, whose service to the geological survey spanned more than three decades. Climate controlled study and examination rooms were made possible through donated funds in the memory of Clark S. Rhoden. McCracken is one of the largest such collections in the nation and is open to the public, by appointment.
Core is a cylinder-shaped segment of subsurface rock obtained by using a hollow-stem drill and drill bit. This method of collection allows for continuous samples through the bedrock zones of interest. Core typically collected for research is 1.375 inches in diameter and stored in 2-foot segments. Cuttings are small pieces of rock that are pushed to the surface as a solid stem drill bit is advanced. Samples of cuttings are collected as they are flushed out of the borehole. The samples are then washed to remove and fine particles and placed into small vials for storage and later examination.
The collection and archiving of core and cuttings helps to preserve geological history, lead to a better understanding of Missouri geology and hydrology, and yield data useful in solving environmental, industrial and engineering problems. By archiving core and cuttings, they can be saved for future research and exploration.
Core and cuttings available for study come from many different sources. Drilling projects from quarries, oil and gas exploration, mineral exploration, landfills, hazardous waste sites and highway department construction have contributed to the holdings at McCracken.