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

"Clast" refers specifically to any fragment of geological detritus, including rock or mineral fragments. In sedimentology, the term is used to describe the individual pieces that make up a sedimentary rock, which can originate from various sources such as weathering and erosion of pre-existing rocks. The size, composition, and shape of clasts are crucial for understanding the sedimentary environment and processes involved in their formation and transport.

In contrast, the other options describe different concepts in sedimentology. For example, a type of sediment that has been compacted refers to lithification processes and not specifically to clasts. A specific layer of sediment in stratigraphy pertains to stratigraphic units or cycles rather than individual clasts. Lastly, a mineral that forms in sedimentary conditions would refer to minerals like calcite or gypsum, which are formed from processes involving sediment, but does not encompass the broader definition of clasts as fragments themselves. Thus, identifying a clast as a geological fragment captures its essence in the study of sediments.