Sandstone

Sandstone, a sedimentary rock, is formed when grains of sand are compacted and cemented together over thousands or millions of years. The sand grains often are composed of the minerals quartz or feldspar that were worn off other rocks and ground down into pebbles.

Sandstone varies in color depending on the color of the sand grains it comprises or impurities it may contain. Outcrops in Kansas range from tan to orange to purplish red. Formations, or layers, of sandstone often are porous and permeable, meaning they contain small pores, or holes, that interconnect and allow fluids to flow through. Water and oil are produced by drilling into underground sandstone formations where they have accumulated.

In Kansas, sandstone was formed along shorelines or in deltas that flowed into different shallow seas that covered all or part of the state during various geologic periods, including the Carboniferous, Permian, and Cretaceous.

The Dakota Formation, a widespread sandstone that crops out on hillsides and can be seen in road cuts in central Kansas, formed from sand deposited on or near the Cretaceous seas that covered much of Kansas 80 million years ago. Historically, Dakota Sandstone was used in the construction of buildings and bridges in central Kansas. Oddly shaped rocks on the surface at Mushroom Rock State Park in Ellsworth County and large spherical rocks at Rock City in Ottawa County are remnants of sandstone that remained after the less durable sandstone around them eroded away.