Sedimentary Rocks Grand Canyon, USA White Cliffs of Dover, England
Sedimentary Rocks Two Categories: Clastic – rocks formed from fragments (pieces) of other rocks Non-clastic – rocks formed chemically or organically
Clast Rock fragment. (clay, silt, sand, etc.)
Deep Water Near Shore Limestone, Rock Salt, Dolostone, etc. Sandstone, Siltstone Conglomerate Shale
Sorting- Refers to the distribution of clast sizes in a rock. • Well sorted- rock with few clast sizes 2. Poor sorted- rock with many different clast sizes
Lithification- the process of turning loose sediment into solid rock. • Compaction • Cementation
Compaction- Pressure pushes objects together into a smaller space.
Chemical rocks- Form when minerals precipitate, or fall out of solution.
Precipitation- water evaporates but the minerals stay (precipitate); opposite of dissolving Salt Flat
Calcite- mineral formed from calcium, carbon, and oxygen. Reacts with acid (dissolves).
Coquina Rock composed primarily of shell and/or coral fragments.
Fossiliferous- Rock containing many fossils (limestone)
Uniformitarianism “The present is the key to the past” • Processes that exist today also existed hundred, thousands, and millions of years ago. • Rock deposition • Weathering & Erosion • Faulting, etc.
Steno’s Three Principles • Principle of Superposition Oldest layers are deposited first; bottom layer 2. Principle of Original Horizontality Sedimentary rock layers are deposited parallel to the ground. 3. Lateral Continuity Rock layers are deposited over very large areas.