Clasts within streams are moved in several different ways, as illustrated in Figure 6.5. Large bedload clasts are pushed (by traction) or bounced along the bottom (saltation), while smaller clasts are suspended in the water and kept there by the turbulence of the flow. As the flow velocity changes, different-sized clasts may be either incorporated into the flow or deposited on the bottom. At various places along a river, there are always some clasts being deposited, some staying where they are, and some being eroded and transported. This changes over time as the discharge of the river changes in response to changing weather conditions.
Other sediment transportation media, such as waves, ocean currents, and wind, operate under similar principles, with flow velocity as the key underlying factor that controls transportation and deposition.
You are viewing: Which Option Gives Two Examples Of Clastic Sedimentary Rock
Read more : Which Elements Are Synthetic
Clastic sediments are deposited in a wide range of environments, including glaciers, slope failures, rivers — both fast and slow, lakes, deltas, and ocean environments — both shallow and deep. Depending on the grain size in particular, they may eventually form into rocks ranging from fine mudstone to coarse breccia and conglomerate.
Lithification is the term used to describe a number of different processes that take place within a deposit of sediment to turn it into solid rock. One of these processes is burial by other sediments, which leads to compaction of the material and removal of some of the intervening water and air. After this stage, the individual clasts are all touching one another. Cementation is the process of crystallization of minerals within the pores between the small clasts, and also at the points of contact between the larger clasts (sand size and larger). Depending on the pressure, temperature, and chemical conditions, these crystals might include calcite, hematite, quartz, clay minerals, or a range of other minerals.
Read more : Which Black Clover Character Are You
The characteristics and distinguishing features of clastic sedimentary rocks are summarized in Table 6.2. Mudrock is composed of at least 75% silt- and clay-sized fragments. If it is dominated by clay, it is called claystone. If it shows evidence of bedding or fine laminations, it is shale; otherwise it is mudstone. Mudrocks form in very low energy environments, such as lakes, river backwaters, and the deep ocean.
Table 6. 2 The main types of clastic sedimentary rocks and their characteristics. Group Examples Characteristics Mudrock mudstone >75% silt and clay, not bedded shale >75% silt and clay, thinly bedded Coal dominated by fragments of partially decayed plant matter, often enclosed between beds of sandstone or mudrock Sandstone quartz sandstone dominated by sand, >90% quartz arkose dominated by sand, >10% feldspar lithic wacke dominated by sand, >10% rock fragments, >15% silt and clay Conglomerate dominated by rounded clasts, pebble size and larger Breccia dominated by angular clasts, pebble size and larger
Source: https://t-tees.com
Category: WHICH
