Geology

Mudcracks

polygonal desiccation features in wet mud

Chemical sedimentary rocks

rocks formed from minerals precipitated from a solution or left behind by evaporation

Detrital sedimentary rocks

rocks that form from the accumulation of materials that originate and are transported as solid particles derived from both mechanical and chemical weathering.

Poorly sorted

sediment with a wide range of grain sizes

Nonclastic

not formed from other rocks or rock particles.

Graded beds

A sediment layer characterized by a decrease in sediment size from bottom to top.

Clastic

A sedimentary rock composed of weathered fragments of older rock.

Understand the use of the term fossil fuel.

Coal is commonly called a fossil fuel. When coal is burned, energy from the sun that has stored by plants many millions of years ago is being used, hence the actual burning of "fossil."

Cross-bedding

Depositional feature of sedimentary rock that forms as inclined layers of sediment are carried forward across a horizontal surface

Fossils

Preserved remains of once-living organisms

Strata or beds

layers of sedimentary rocks

What are the two primary ways that sediments are lithified into sedimentary rocks?

Sedimentary rock is one of the three main rock groups (along with igneous and metamorphic rocks) and is formed in four main ways: by the deposition of the weathered remains of other rocks (known as 'clastic' sedimentary rocks); by the accumulation and the consolidation of sediments; by the deposition of the results of biogenic activity; and by precipitation from solution.

Be prepared to distinguish between shale, sandstone, conglomerate, breccia, limestone, coquina, chalk, travertine, dolostone, chert, evaporites, and coal based on the information provided in your text. Understand the conditions under which each of these rocks formed.

Shale is made mostly of small grains of clay minerals. It accumulates in low-energy depositional environments such as the deep sea, lake bottoms, and floodplains adjacent to rivers. Shale is fissile due to the alignment of microscopic clay flakes parallel to bedding. Contain a lot of organic material accumulates in low-oxygen environments and is characterized by a black color. Sandstone is dominated by sand-sized grains. Sandstones may exhibit various degrees of sorting, in which similar-sized grains are deposited together Conglomerate and breccia are characterized by a high portion of gravel-sized grains. If deposited by water, a conglomerate implies a very energetic current, one capable of moving gravel. Grains in a breccia are angular, indicating that the material was deposited closer to its source area. Conglomerate is made of rounded grains, implying a significant amount of transport before deposition. Limestone is the most common chemical sedimentary rock. It forms mainly in shallow, warm ocean settings. Limestone is dominated by calcium carbonate. This is the material from which corals construct reefs. Coquina and chalk are also examples of biochemical limestone. Travertine and oolitic limestone are examples of inorganic limestone. Dolostone is a chemical sedimentary rock that is dominated by the mineral dolomite. Like calcite, dolomite is a carbonate mineral, but about half of ots calcium ions have been replaced by magnesium ions. Chert is the general term for rocks made of microcrystalline silica. If the chert is red, it is called jasper. Black chert is flint. Agate is multicolored. Evaporate deposits form when minerals precipitate from an ever-more-concentrated solution of dissolved ions. This is how the vast salt flats of American West formed. Coal forms from the burial of large amounts of plant matter in low-oxygen depositional environments such as swamps and bogs. Through compression, the peat becomes compressed into low-grade form of coal called lignite.

Ripple marks

Small waves of sand that develop on the surface of a sediment layer by the action of moving water or air.

Sorting

The degree of similarity in particular size in sediment in sedimentary rock.

Environment of deposition

The location in which deposition occurs, usually marked by characteristic physical, chemical, or biological conditions.

Lithification

The process that converts sediments into solid rock by compaction or cementation.

Understand the process that forms coal and be prepared to distinguish between peat, lignite, bituminous coal, and anthracite

Through compression, the peat becomes compressed into a low-grade form of coal called lignite, Lignite can be compressed further, driving out volatile components and concentrating carbon to make higher-grade bituminous coal. Metamorphism accompanying mountain building can take this concentration proceed even further, producing the highest grade coal, anthracite.

Diagenesis

a collective term for all the chemical, physical, and biological changes that take place after sediments are deposited and during and after lithification

Well sorted

all clasts have nearly the same grain size

Bedding planes

flat surfaces along which rocks tend to separate or break