Question

How can you distinguish a clastic rock from that of a bioclastic rock

Answer 1

Bioclastic rocks are actually sub-parts of clastic rocks, not a completely different thing altogether.

Clastic rocks are made up of loosened bits of pre-existing rocks. These rocks are formed from weathering, breaking those larger rocks down into little particles (for example, a grain of sand) due to external weather factors such as wind or rain. Some examples of these rocks would be sandstone, conglomerate, and silistone. They are classified by the size and shape of the fragments they are made up of.

Bioclastic rocks are also made up of loosened bits, however, they are not made of rock. They are made of fossils and biogenic (made by living organisms) particles (for example, pieces of shells and coral). These rocks are formed from small parts of pre-existing organisms compacting together to form a rock. Examples of this type of rock would be coquina and limestone, or more specifically, bioclastic limestone. Bioclastic rocks have a very crystalline texture and it is highly likely that you will see a shell in this rock type.