Piikkikerros

Piikkikerros, which translates to "spine layer" or "spiky layer" in English, is a geological term used to describe a specific type of sedimentary rock formation. It is characterized by the presence of abundant, sharp, and often angular clasts, or fragments, that are embedded within a finer-grained matrix. These clasts are typically larger than the surrounding matrix material, giving the rock a distinctive rough and protruding texture, hence the name "piikkikerros."

The formation of piikkikerros is generally associated with environments where rapid erosion and deposition occur, often in close proximity to the source of the fragments. This can include areas such as alluvial fans, debris flows, and glacial outwash plains. The angularity of the clasts suggests limited transport distance, as prolonged abrasion would typically round them. The composition of the clasts can vary widely depending on the local geology of the area from which they were derived. The matrix binding these fragments can be sandy, silty, or even clayey, and its cementation can range from poor to very strong, influencing the overall rock strength and durability. Piikkikerros can be found in various geological settings and is often studied to understand past environmental conditions and tectonic activity.