Salem Limestone - Its origin in the Salem Sea (DS-04)
More than 300 million years ago a shallow inland sea covered vast areas of North American including most of the Midwest. The sea literally teemed with a varied fauna of invertebrate organisms that extracted calcium carbonate from the water for their shells and skeletons. Their fossilized remains, with limy muds that precipitate from sea water, slowly accumulated into thick deposits that eventually became limestone.

The thick-bedded Salem Limestone contains tiny, rounded shells of foraminifers, with other small fossils and the fragments of larger shells, all winnowed by wave action and currents to uniform size, which give it an even texture. Buff stone is the more desirable for some purposes. Gray stone is more abundant. Mixed gray and buff stone is termed variegated. Architects may mix the colors or specify a single variety.

Our Hoosier State Beneath Us: Dimension Stone