ASBOG Practice Exam 2025 – Comprehensive All-in-One Guide to Ace Your Geology Licensure!

The correct answer is sedimentary rock, which predominantly forms from the accumulation and compaction of organic materials, along with other sediment. This rock type is characterized by the presence of fossils and often has distinct layers that reflect the environment of deposition. Organic materials, such as plant debris, shells, and microorganisms, are crucial components in the formation of certain sedimentary rocks, like coal and limestone.

Sedimentary rocks can form in various settings, including lakes, riverbeds, and oceans, where organic material can accumulate over long periods. The process involves biological activity that contributes to the building of these rocks, underscoring the importance of organic materials in their formation.

Other rock types do not primarily stem from organic materials. Igneous rocks form from the cooling and solidification of molten rock, while metamorphic rocks arise from the alteration of existing rocks under heat and pressure. Volcanic rock, a subtype of igneous rock, specifically results from eruptive processes and lacks the organic characteristics seen in sedimentary formations.