Chalk is classified as which type of sedimentary rock?

Chalk is classified as which type of sedimentary rock?

• A. Clastic
• B. Chemical
• C. Biochemical
• D. Organic

Answer: (C)

Sedimentary rocks are categorized by how they originate. Chalk forms from the remains of tiny marine organisms whose calcium carbonate shells accumulate and lithify, so it is a biochemical sedimentary rock. This biogenic origin makes it different from clastic rocks, which are built from cemented fragments of preexisting rock; from chemical rocks, which form by minerals precipitating directly from water; and from organic rocks, which are made mainly from accumulated plant or animal matter like coal. The defining feature of chalk is the biological production of its carbonate material, not mere chemical precipitation or fragments.

Sedimentary rocks are categorized by how they originate. Chalk forms from the remains of tiny marine organisms whose calcium carbonate shells accumulate and lithify, so it is a biochemical sedimentary rock. This biogenic origin makes it different from clastic rocks, which are built from cemented fragments of preexisting rock; from chemical rocks, which form by minerals precipitating directly from water; and from organic rocks, which are made mainly from accumulated plant or animal matter like coal. The defining feature of chalk is the biological production of its carbonate material, not mere chemical precipitation or fragments.