The Fort Hays Limestone is a member of the Niobrara Formation of the Colorado Group exposed in Colorado, Kansas, Nebraska, and South Dakota and is named for the bluffs near the old Fort Hays, a well-known landmark in western Kansas.

[1][2] Defining the southeast border of the High Plains, the towering stone-capped bluffs of the Fort Hays Escarpment are "perhaps the most conspicuous physiographic boundary in Kansas.

The Fort Hays Limestone was a generally practical building stone.

However, it deteriorates when in contact with soil (note the repaired foundation on the Old Fort Hays Blockhouse).

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