sedimentary()
A.游牧民;游走的
B.沉积的、沉淀性的
C.基础的、简单的
D.补充的
A.游牧民;游走的
B.沉积的、沉淀性的
C.基础的、简单的
D.补充的
Sedimentary rocks are composed largely of minute fragments derived from the disintegration of existing rocks and in some instances from the remains of animals. As sediments are transported, individual fragments are assorted according to size. Distinct layers of such sediments as gravels, sand, and clay build up, as they are deposited by water and occasionally wind. These sediments vary in size with the material and the power of the eroding agent. Sedimentary materials are laid clown in layers called strata.
When sediments harden into sedimentary rocks, the names applied to them change to indicate the change in physical state. Thus, small stones and gravel cemented together are known as conglomerates; cemented sand becomes sandstone; and hardened clay becomes shale. In addition to these, other sedimentary rocks such as limestone frequently result from the deposition of dissolved material. The ingredient parts are normally precipitated by organic substances, such as shells of clams or hard skeletons of other marine life.
Both igneous and sedimentary rocks may be changed by pressure, heat, solution, or cementing action. When individual grains from existing rocks tend to deform. and interlock, they are called metamorphic rocks. For example, granite, an igneous rock, may be metamorphosed into a gneiss or a schist. Limestone, a sedimentary rock, when subjected to heat and pressure may become marble, a metamorphic rock. Shale under pressure becomes slate.
Which one of the following is a metamorphic rock?
A.Granite.
B.Shale.
C.Slate.
D.Limestone.
A.concealed
B.eroded
C.protected
D.softened
Hornfelsis a metamorphic rock formed when magma(molten rock) heats sedimentary rocks on Earth’s sur-face. According to Figure 1, hornfels is most likely amember of which of the following facies?
A.Facies A
B.Facies C
C.Facies E
D.Facies G
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