Geo. 101 – 1st Edition Lecture 12 Outline of Last Lecture I. OverviewII. Weathering Outline of Current Lecture I. Sedimentary Rocksa. Texturesb. Clastic, Biochemical, ChemicalII. Sedimentary StructuresIII. Diagenesisa. LithificationCurrent LectureSedimentary Rocks- Abundance of Rock Types:o Siltstone, Mudstone, Shale  75%o Sandstone Conglomerate  11%o Carbonate Rocks  14%*Chemical Precipitates (very minor portion of rocks) - Texture is affected by transportation processo Particle Size: clay, slit, sand, gravel (pebble, cobble, boulder)o Shape: Angular to well-rounded (smoothing of edges) Rounder stones = Longer transportation processo Sorting: The particles are about the same size If yes: Well-sorted -- If no: Poorly-sorted - Clastic/Detrital Sedimentary Rocks:o Classified by texture Size, shape, and arrangemento Composed of pieces of pre-existing rocks (clastic sediment)- Biochemical Sedimentary Rocks:o Comprised of the remains of organisms (plants and animals)o Classified by composition EX: Limestoneo Shallow Marine – Reef ; if vegetation – Swamp These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Clastic Rocks- Chemical Sedimentary Rocks:o Composed of minerals precipitated out of solution  EX: Salt from evaporated sea watero Looks Crystalline (by crystals will be very small)o Classified by composition (minerals)Sedimentary Structures:- Bedding (Stratification)o Parallel layers of sedimentso Each layer is called a ‘bed’- Cross-Beddingo Sets of bedded sediments at an angle to horizontalo Deposited by currents (wind or water) Ex: Duneso Cross-Bedding indicates the direction of current- Graded-Beddingo Beds progress from coarse grains at bottom to fine grains at top of bedo Indicated waning of current- Ripple Markso Wavy lines formed by waves or currentso Smaller scale than cross-bedso Common on shoreline- Mud Crackso Polygonal pattern of cracks that develop in dried mud Ex: Mudflats- Bioturbation:o Burrow marks made by animals in the sediment EX: Clams, Gooey DucksDiagenesis:- The chemical and physical changes that transform sediment into rocko Lithification: hardening of soft sediments into rock Compact: pore space volume (weight overlying sediment) Cementation: chemically precipitated