GL102 Lecture Notes - Lecture 6: Ripple Marks, Permineralization, Pyrite
Document Summary
Conglomerate is generally rounded pebbles and cobbles that vary greatly in size. Coarse particles in a conglomerate indicate strong wave activity or stream action. Solution moved to lakes or seas then deposited. Coral reefs, coquina (broken shells), fossiliferous limestone and chalk (microscopic organisms) Include travertine (caves) and oolitic limestone (with spherical grains) Composed of calcium-magnesium carbonate mineral dolomite (mg replaces some ca) Varieties include flint and jasper (banded form is called agate) Occurs as nodules in limestone and as tabular layers. Examples include rock salt (nacl), rock gypsum (caso4-2h2o), and sylvite (kcl; potash, used as fertilizer) Salt flats - dissolved material precipitated as white crust on ground. Order of increasing temp and pressure of formation: Flat surfaces that separate strata (originally horizontal) Rapid deposition from water; coarse material settles first. Low angle laminations with undulations (up to 1 m long), formed by storms. Only a tiny fraction of organisms for the geologic past have become fossilized.
