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Breccia

Pictures of Sedimentary Rock Types

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Breccia is a rock made of smaller rocks, like conglomerate. But breccia contains sharp, broken clasts while conglomerate has smooth, round clasts. (more below)
Not a type but a process
Photo (c) 2008 Andrew Alden licensed to About.com
Breccia ("BRET-cha") is usually listed under sedimentary rocks, but igneous and metamorphic rocks may become shattered, too. It is safest to think of brecciation as a process rather than breccia as a rock type. As a sedimentary rock, breccia is a variety of conglomerate.

There are many different ways to make breccia, and usually geologists add a word to signify the kind of breccia they're talking about. A sedimentary breccia arises from things like talus or landslide debris. A volcanic or igneous breccia forms during eruptive activities. A collapse breccia forms when rocks are partly dissolved, such as limestone or marble. One created by tectonic activity is a fault breccia. And a new member of the family, first described from the Moon, is impact breccia. This specimen, in Upper Las Vegas Wash in Nevada, is probably a fault breccia.

Some big close-up pictures of breccia are available as free wallpaper images.

For more photos see the Sedimentary Rocks Gallery.

Other galleries:
Fossils
Geologic Features and Processes
Glaciers and Ice
Landforms
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Rocks
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