Cap-rock is a geological term used to describe a hard, resistant layer of rock that covers softer layers underneath. It acts as a protective cap, shielding the underlying formations from erosion. This term is often used in the context of rock formations such as mesa, butte, or plateau. Synonyms for cap-rock include capstone, hard layer, resistant formation, protective sheet, or armor layer. These terms all capture the essence of cap-rock – a durable, tough layer that stands above and protects the underlying geological structures. Whether referring to a prominent feature of a mountain or a geological phenomenon, these synonyms help convey the role and characteristics of cap-rock in various contexts.