cast « Back to Glossary IndexMaterial filling in a cavity left by a organism that has dissolved away. Synonyms: internal cast, external cast, castsRelated Articles: 4 Igneous Processes and Volcanoes5 Weathering, Erosion, and Sedimentary Rocks7 Geologic TimeGlossary: sole markGlossary: authigenic mineralization« Back to Glossary Index Author: Chris Associate Professor, Salt Lake Community College, Salt Lake City, Utah View all posts by Chris