Clastic

Clastic, in geology, describes rocks and sediments formed from fragments (clasts) of pre-existing rocks, minerals, or organic materials. These fragments are transported and eventually deposited, undergoing compaction and cementation to form a new rock. The size and composition of the clasts, along with the cementing material, determine the characteristics of the resulting clastic rock. This process is fundamental to the formation of many sedimentary rocks and is driven by weathering, erosion, transportation, and deposition.

Clastic meaning with examples

• The sandstone cliff revealed a striking example of clastic structure, with clearly visible sand grains cemented together over time. The varied sizes and shapes of these clasts, transported by ancient rivers, provided evidence of past geological processes. Geologists often analyze the composition of clasts to understand the source rocks from which they originated.
• During the flood, the river deposited a significant amount of clastic sediment, ranging from fine silts to coarser gravels, reshaping the landscape. Examining the mineralogy of these clastic deposits could indicate the surrounding areas the water had traveled through. This varied clastic material showcased the river's erosive power and transport capacity.
• The breccia, a clastic rock composed of angular fragments, indicated a high-energy environment where fragments hadn't been worn down by prolonged transportation. Analyzing the clast size distribution and composition can indicate the specific depositional environment of the rock formation. The cement that bound the clasts together indicated the chemical conditions present during rock formation.
• Researchers studying the ancient lakebed discovered a layer of shale, a fine-grained clastic rock composed primarily of compacted clay minerals. The uniform size of the clasts suggested slow deposition in a calm environment. By comparing these clasts to other known samples, the researchers can find clues about the origin and formation of the lake.