GSC 110 Lecture 2: Test 2
28 Apr 2016
School
Department
Course
Professor
Document Summary
Rock formed at or near earth"s surface from fragments or dissolved constituents of pre-existing rock. Make up 1% of earth"s mass but 80% of earth"s surface. Steps in formation: weathering: in place chemical alternating and mechanical breakdown of rocks during exposure to weather. Physical (mechanical): breaking of rock into smaller fragments. Types: joints/jointing= naturally formed cracks in rocks. Causes outer rock layers to break into sheets. Chemical weathering: contact with air or water solutions alters/destroys minerals in rock. Happens in warm, wet, conditions (faster in tropics) slower in deserts and near poles. Minerals differ in their susceptibility to chemical weathering: within the silicate minerals ones with the least linkage are the most susceptible (quartz sand beaches) Common reactions: dissolution: dissolving into ions (salts, carbonate minerals, like acid rain, hydrolysis: water loosening original mineral plus water causes ions and clay minerals (common process in soil, oxidation: pyrite plus oxygen produces iron oxides.
