Note: Use Internet Explorer to view this page. For information on salt mining in Michigan, please see: Dry (Rock Salt) Mining on the Salt Institute's website.
See also: Saline (MI) Salt Springs: A History on the Saline Area Historical Society website.
During the Paleozoic Era, beginning about 600 million years ago and ending about 230 million years ago, seawater invaded the Michigan Basin at least six times.
As the seas receded and evaporated, rock and mineral deposits such as halite (rock salt), gypsum (calcium sulfate with water), liquid brines, petroleum, lime, clay, sandstone and coal were left behind.
During the early decades of the 20th century, Michigan led the nation in salt production. Michigan is a leading producer of many natural salines -- underground waters rich in chlorides, calcium, magnesium, sodium and, in lesser amounts, potassium, bromine and iodine. Salt under Michigan has created fortunes, towns and manufacturing centers.
Michigan ranks first in the United States in the production of calcium chloride (salt) and in gypsum, fourth in cement and sand and gravel, and is a large producer of crushed stone for a variety of purposes. These minerals are found in the sedimentary rocks of the Michigan Basin or in the extensive glacial deposits.
Salt is obtained from beds of rock salt (the Salina Formation is but one) over 1,100 ft below the surface in Detroit and from natural and artificial brines of dissolved salt that are pumped to the surface in Midland, Manistee, Muskegon, Wayne, and St. Clair Counties. The salt layers were laid down as evaporite deposits in the seas of the middle Paleozoic era -- in the Mississippian, Devonian, and Silurian periods.
Long before settlers entered Michigan Territory, wild animals discovered numerous salt springs and used them as natural salt licks (see the map below). Discoveries of musk oxen and mastodon bones in Michigan often are related to these salt seeps. [Note the location of salt seeps in Washtenaw County, and the high concentration of mastodon finds. See also: Mastodons in Pittsfield Township.]
Indians took salt from the same springs and sometimes used it as an item of trade with neighboring tribes. Some of the earliest white settlements were begun at brine springs in the southeastern part of the state. (Brine is water saturated with common salt.) [Note: "Saline" means salty. Saline, Michigan derives its name from nearby salt springs.]
Salt was so important to early pioneers that during the winter of 1836-37 in Branch County a 20-pound venison ham could be traded for a fist-sized lump of salt. Used mainly as a preservative, salt was essential for survival on the Michigan frontier. Though Michigan possessed an abundance of salt springs, they were not commercially developed in the 1830s, and Michigan residents spent $300,000 annually on imported salt. Salt was so important that those in favor of internal improvements in the late 1830s used it as an example of an eastern commodity made more readily available by the building of Michiganís first railroad line.
Source: The Salt Institute. See Dry (Rock Salt) Mining on its website. This entry is included here with the permission of the Salt Institute. Brief supplemental notes and links have been added to their content. The Salt Institute notes on its website that some of the images and text on this page were taken from various issues of Michigan History magazine and from C.M. Davisí Readings in the Geography of Michigan (1964).