GEOG 101 Lecture Notes - Lecture 20: Diatomaceous Earth, Gneiss, Tsavo
Document Summary
Types of sedimentary rocks: mechanically formed sedimentary rocks. Sedimentary rocks formed when weathered igneous or metamorphic rocks are deposited and compacted e. g. sandstone and shale: organically formed sedimentary rocks. Sedimentary rocks formed when animal and plant or animal remains are buried, compressed and compacted. Classification of organically formed sedimentary rocks (i) calcareous rocks-rich in calcium carbonate e. g. chalk and limestone. Sedimentary rocks formed when materials dissolved in water chemically react forming new substances then water evaporated leaving layers of those salts. Classification of chemically formed sedimentary rocks (i) carbonates e. g. trona and dolomite (ii) sulphates-sulphate compounds (iii) chlorides e. g. halite (iv) silicates e. g. flint (v) iron stones e. g. haematite and limonite: metamorphic rocks. Rocks which have changed their physical appearance and chemical properties as a result of subjection to great heat and pressure e. g. gneiss from granite. The major rocks are metamorphic rocks e. g. marble in parts of machakos and schist and. Eastern kenya region gneiss in parts of kitui.
