Why Basalt is Called Traprock

Why Basalt is Called Traprock
Basalt (large)

Basalt, characterized in the photograph above by abrupt angular ledges, is one of the most common igneous rocks in the world. This particular example of was found within Black Pond State Wildlife Management Area on Beseck Ridge, just one mountain in a chain of “traprock” cliffs that cut through Central Connecticut.

The term “traprock” is synonymous with basalt, but the reason for such a nickname isn’t too obvious. Actually, the “trap-” prefix comes from a Scandinavian word meaning “step” or “stair”, referring to the suggestive way in which basalt fractures.

Although freshly exposed traprock tends to range in color from gray to nearly black, you’ll notice that the aged rock face in this photograph has taken on a reddish tone. Basalt is rich in iron, so after being exposed to rain and humidity for long periods of time, it will actually begin to rust.

Be sure to take a look at our short video, Quick Facts: Basalt, to learn more about traprock and see differently-shaped formations.

About this Photograph
Photograph of Basalt © 2011 J.G. Coleman Photography. View more photography by Trails of Freedom Chief Researcher, Justin Coleman, at J. G. Coleman Photography.