10 Properties of Sedimentary Rocks | UPSC| Geography
(1) Sedimentary rocks are made of sediments produced from earlier rocks, plant and animal remnants, and so include plant and animal fossils. The age of the creation of a certain sedimentary rock may be established by analyzing the fossils contained in that rock.
(2) Sedimentary rocks cover the majority of the earth’s surface. Sedimentary rocks are thought to cover around 75% of the earth’s surface area, with igneous and metamorphic rocks covering the remaining 25%. Despite having the greatest covering, sedimentary rocks account for only 5% of the crust’s composition, with igneous and metamorphic rocks accounting for the remaining 95%. As a result, it is clear that sedimentary rocks are significant for extent rather than depth in the earth’s crust.
(3) The deposition of diverse types and sizes of sediments to produce sedimentary rocks occurs in a specific sequence and system. From the coastal borders to the center of the water bodies or sedimentation basins, the size of the sediments diminishes. Different types of cementing materials, such as silica, iron compounds, calcite, clay, and so on, consolidate and compress different types of sediments.
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(4) Sedimentary rocks have several layers or strata, although they are seldom crystalline rocks.
(5) Sedimentary rocks, like igneous rocks, do not exist in vast formations such as batholiths, laccoliths, dykes, and so on.
(6) Sedimentary rock layers are rarely encountered in their original and horizontal orientation. Because of lateral compressive and tensile stresses, sedimentary strata are usually distorted. The beds are folded and come in anticlinal and synclinal varieties. Tensile and compressive forces also cause faults owing to bed displacement.
(7) Sedimentary rocks can be well-consolidated, weakly consolidated, or unconsolidated. The type of the cementing elements and rock building minerals determines the composition of the rocks.
(8) Different sizes of joints distinguish sedimentary rocks. These are almost always perpendicular to the bedding planes.
(9) The bedding plane is the connecting plane between two successive beds or strata of sedimentary rocks. Conformity refers to the consistency of two beds along a bedding plane (i.e., when beds are similar in all respect). The structure is known as unconformity when two successive beds are not uniform or conformal. In actuality, an unconformity is “a gap in a stratigraphic sequence produced by a change in conditions that caused deposition to suspend for a significant time.”
(10) Because of lateral compressive and tensile stresses, sedimentary strata are usually distorted