Friday, February 11, 2011

Sedimentary Rock

Sedimentary Rock

Igneous rock that is uncovered to the Earth’s surface will undergo destruction (erosion) by the influence of weather, then it is transported by natural power such as water, winds or glaciers and it got sediment in another places, so sedimentary rocks formed.

According to the formation process, sedimentary rocks are separated into:

a. Clastic or Mechanic Rock.
It is formed from the clump of larger rock that is carried from the slope of mountain, through the rain water then it is carried by river flow and then it is got sediment in a downstream region in the form of sand the chemical composition of which is still same with original rock. It means the sedimentation does not undergo a chemical process, but only a mechanical process.

The example of clastic rock are: brexi rock, conglomerate rock, sand and clay.

b. Chemical Rock.
chemical rock
It is formed through a chemical process, such as it undergone by a limestone in the cove’s roof. The limestone is permeated by the rainwater that contains carbondioxide will dissolve in the form of lime water solution. Some solution drop from cave’s roof and fall to the dry base of cave, the rest stick on the ceiling of the cave, so it is formed a limestone sediment as the remain of vaporization of lime water when that solution drops. Stalactite and stalagmite are formed, which are one of process produced by chemical rocks.

c. Organic Rock.
It is formed from the accumulations of animal and plant remains.

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