In Kansas, the mineral halite, also known as common salt or table salt, was deposited in a shallow sea during the Permian Period. As the sea evaporated, the halite became very concentrated, and thick layers gradually built up on the sea floor. Over time, the salt was buried under layers of other sediment and rock, which compacted it and prevented it from dissolving in the rain. Salt in thick underground layers is known as rock salt.
The thickest and most extensive salt layer in Kansas is the geologic formation known as the Hutchinson Salt Member, which underlies approximately 37,000 square miles of central Kansas. About 500 to 1,000 feet deep in much of Kansas, it is, on average, 250 feet thick.
The rock salt in Kansas remained hidden for millions of years until companies speculating for oil, gas, coal, and other minerals drilled into the Hutchinson Salt Member in 1887. The salt was first mined by pumping water down wells and dissolving the salt. Underground mining started in Hutchinson in 1923, and salt is still mined in Hutchinson, Kanopolis, and Lyons.
Buchanan, R., 2010, Kansas Geology: An Introduction to Landscapes, Rocks, Minerals, and Fossils (2nd ed.): Lawrence, Kansas, University Press of Kansas, 240 p.
Buchanan, R., and McCauley, J. R., 2010, Roadside Kansas: A Traveler's Guide to Its Geology and Landmarks (2nd ed.): Lawrence, Kansas, University Press of Kansas, 392 p.
Kansas Rocks and Minerals, Kansas Geological Survey Educational Series 2
Klein, C., 1993, Manual of Mineralogy (after James D. Dana), 21st Edition: New York, Wiley, 681 p.
Sawin, R. S., and Buchanan, R. C., (2002), Salt in Kansas: Kansas Geological Survey, Public Information Circular 21.