Silt rock, also known as mudstone or shale, is a sedimentary rock formed from the accumulation of tiny particles of silt and mud. It is a common type of rock found around the world and is often used in construction and landscaping. Other synonyms for silt rock include argillite, claystone, and marlstone. These rocks are all composed of similar materials, with varying degrees of silt and clay content. They are commonly used as building materials due to their strength and durability, especially in areas where more porous rocks would erode quickly. Silt rock can also contain fossils, providing important clues to the history of the area in which it was formed.