BRECCIAS ARE LITHIFIED SEDIMENTS with the same size clasts as conglomerates, but in breccias the clasts are angular or only slightly rounded. The lack of rounding indicates little or no transportation has taken place. Breccias can form in several ways: firstly, a rock body can break and then become cemented in its original position; secondly, rock fragments accumulating at the base of a cliff can become cemented where they fell; thirdly, in areas of active faulting, newly broken material along the line of the fault can be cemented in place; and fourthly, where faulting takes place underwater, newly shattered material can move in underwater landslides and become cemented.
- Rock type Marine, freshwater, and glacial detrital sedimentary
- Fossils Very rare
- Major minerals Any hard mineral can be present
- Minor minerals Any mineral can be present
- Color Varies
- Texture Very coarse, angular clasts
Colour Variable. Texture Consists of angular rock fragments (2 mm to many metres in diameter) set in a fine- to medium-grained matrix. In...
Rock comprising angular fragments set in a fine-grained matrix. Breccias form as a result of rocks being crushed by meteoroid impacts, tectonic...
Whereas igneous and metamorphic rocks are produced by internal processes within the Earth, sedimentary rocks are formed by processes which are...