by Rick Scott
"The photo above showing a huge outcrop of breccia was taken in Fall Canyon at Death Valley National Park, California. Breccia typically forms when angular fragments (over 2mm in diameter) of rock accumulate in streambeds and alluvial fans, for instance. The pieces become bound by mineral cement or are fixed by much smaller particles that fill the spaces between the angular pieces. A debris flow is one condition where binding of the fragments can happen. Another such condition is a meteor impact crater. Breccia is similar to conglomerate, but in conglomerate the fragments are more rounded, indicating that they've traveled further (are more eroded) before cementation occurs."