Which statement concerning sedimentary rocks is NOT true?
A) They may contain fossils that provide clues about ancient life forms.
B) They cannot be derived from metamorphic rocks..
C) They can be formed by glaciation.
D) They are composed of particles and constituents derived from weathering and erosion of other rocks.
The correct answer and explanation is :
The correct answer is:
B) They cannot be derived from metamorphic rocks.
Explanation:
Sedimentary rocks are formed from the accumulation and cementation of mineral and organic particles or by the precipitation of minerals from water. Let’s analyze each statement:
A) They may contain fossils that provide clues about ancient life forms.
This statement is true. One of the most notable features of sedimentary rocks is that they can contain fossils, which are the remains or traces of ancient organisms. Fossils are often preserved in the layers of sediment that form the rock. Fossils help scientists understand the history of life on Earth, the environmental conditions at the time of deposition, and the evolution of life forms.
B) They cannot be derived from metamorphic rocks.
This statement is not true. Sedimentary rocks can indeed be derived from metamorphic rocks through a process called weathering and erosion. When metamorphic rocks are weathered, the minerals and particles from them can be broken down into smaller fragments and transported by wind, water, or ice. These particles can then accumulate and form sedimentary rocks. For example, a metamorphic rock like schist could be eroded, and the resulting material could become part of a sandstone or shale, which are types of sedimentary rocks. Therefore, metamorphic rocks can contribute to the formation of sedimentary rocks.
C) They can be formed by glaciation.
This statement is true. Sedimentary rocks can form as a result of glaciation. Glaciers move large amounts of material, such as rocks, sand, and silt, which can be deposited in different environments. When glaciers melt, the debris carried by the ice can accumulate and form various types of sedimentary rocks, such as tillite, which is a type of rock formed from glacial deposits.
D) They are composed of particles and constituents derived from weathering and erosion of other rocks.
This statement is true. Sedimentary rocks are often made up of particles derived from the weathering and erosion of pre-existing rocks, which can include igneous, metamorphic, and other sedimentary rocks. The fragments of these rocks are transported by natural forces and deposited in layers, eventually becoming cemented together to form a new sedimentary rock.
In conclusion, sedimentary rocks can be derived from metamorphic rocks, so statement B is the one that is not true.