Sediment and Sedimentary Rocks Physical Geology

Sedimentary Rocks This is the most common rock type on Earth’s surface Weathering creates sediment, ready to be transported This is made up of derived from pre-existing rocks We have two types of sediments: Detrital Chemical

Formation Weathering Erosion Transport Deposition Lithification

Sedimentary Rocks Transportation Running water, wind, glaciers, waves, currents all are transportation methods of sediments Transportation can involve suspension as well as ions being dissolved in solution Typically, the longer the transport process, the more rounded the sediment

Sedimentary Rocks Depositional Environments: Terrestrial Transitional Marine

Depositional Environments Terrestrial or Non-Marine Soils Lakes (fresh water, fine sediments) Glacial (Poorly sorted, angular) River/Fluvial (wide variety)

Depositional Environments Transitional Beach Barrier islands Deltas Organic reefs

Depositional Environments Marine Shelf (coarser to finer as you move farther from shore) Continental slope Abyss (turbidity currents, graded bedding)

Lithification Sediments form sedimentary rocks through lithification Compaction Weight of overburden reduces porosity Cementation Chemical precipitation of minerals in pores (cement) Examples: Calcium carbonate Silica Pyrite

Types of Sedimentary Rocks Detrital Consists of particles (detritus) of rocks Also referred to as clastic texture Classified “primarily” by size Gravel > 2mm Sand 2mm-1/16mm Mud rocks Silt 1/16 – 1/256 mm Clay < 1/256 mm

Types of Sedimentary Rocks Classification can be by shape: The more weathering and transportation a particle undergoes, the more rounded the particle Classification can also be by composition: How much of a specific mineral is present

Type of Sedimentary Rocks Gravel: Conglomerate (rounded gravel) Breccia (angular breccia)

Type of Sedimentary Rocks Sand: Sandstone Arkose (mixed variety of sand-sized particles)

Type of Sedimentary Rocks Silt: Siltstone Clay: Shale

Types of Sedimentary Rocks Chemical Sedimentary Rocks Formed by chemical precipitation from solution Biochemical There is an organism involved with the production of biochemical rocks. Evaporites Inorganic chemical precipitates

Types of Sedimentary Rocks Biochemical: Examples: limestone, chert, coal

Types of Sedimentary Rocks Evaporates: Rock gypsum, rock salt

Sedimentary Resources Sand and gravel are used in construction Clay is used for ceramics Evaporties are used for salt and sheet rock Coal is an important fuel source Placer deposits  where we can look for minerals like gold and diamonds