Sedimentary Rocks

Rocks are sedimentary rocks formed from the accumulation of material reshuffle results pre-existing rocks or the result of chemical activity or organism, which was deposited layer by layer on the surface of the earth which then harden.
(Pettjohn, 1975)

So many kinds of sedimentary rocks and spread out very wide with a thickness between a few centimetersampai several kilometers. Also butirnya size from very fine to very coarse and some of the important processes are included into sedimentary rocks. Compared with igneous rocks, sedimentary rocks cover only a small percentage of the earth's crust. Sedimentary rocks only 5% of all rock - rock on the earth's crust. Than 5% of this amount, the rock is 80% clay, sandstone and limestone 5% estimate - about 80%.

Based on the presence or absence of sediment transport processes can be divided into 2 types:
1. Clastic rocks Sediments
Sedimentary rocks are formed from other rock debris. Then experience subsequent transportation and deposition of experienced diagenesis.

2. Non-clastic sedimentary rocks
Namely sedimentary rocks that have not undergone the process of transportation. Formation is a chemical and organic.

Properties - the main properties of sedimentary rocks:

• The presence of bedding plane, indicating the existence of sedimentary structures sedimentation process.
•  Clastic nature of which indicates that the grain - the grain never left, especially in the detritus group.
• The nature trail of the former - the former signs of life (fossils).
• If the character of rock crystal, always monomineralik, for example: gypsum, calcite, dolomite and rijing.

Volume of sediment and rock metasedimen including only contains 5% of known thickness in litofera 10 miles outside the continental margin, where the igneous rock containing 95% metabeku. Meanwhile, the appearance on the surface of the earth, the rocks - sedimentary rocks occupy 75% area of the earth, whereas igneous outcrop of 25% only. Sedimentary rock layers that started from very thin to very thick. The thickness of sedimentary rocks between 0 to 13 kilometers, just 2.2 kilometers thickness of the exposed continental section. Other major form is not visible, every outcrop has a different thickness and general outcrop that looks just 1.8 kilometers in thickness. At the bottom of the sea filled with sediment from coast to coast. The thickness of the layer is always uncertain because any time is always increasing its thickness. Owned thickness varies from a thinner than 0.2 kilometers to more than 3 kilometers, while the thickness - average about 1 kilometer.

Total volume and mass of rocks - sedimentary rocks on Earth have different estimates - the difference, as well as ways to know the right amount. Some experts in the field have been trying to find out the thickness - average of sedimentary rock layers in the earth. Clarke (1924) once the first estimate of sediment thickness in the continental shelf is 0.5 kilometers. In the deep basin, the thickness is higher, the layer thickness continues to increase from the alteration of igneous rocks, oxidation, karonasi and hydration. Thickness will be increased from the debris on the continent so that the thickness will reach 2200 meters. The volume of sedimentary rocks from Clarke's calculation was 3.7 x 108 cubic miles.
(Danang Endarto, 2005)