Question

In what nonmarine settings do gravelly sediments often accumulate?

Short answer

Gravelly sediments often accumulate in nonmarine settings such as fast-flowing rivers, alluvial fans, glacial landscapes, and areas prone to landslides and debris flows. These locations experience enough energy to transport and deposit coarse-grained particles, resulting in the formation of gravelly sediments.

Step-by-step solution

Understanding the types of nonmarine settings

Nonmarine settings refer to environments that are not directly influenced by seawater or marine processes. These environments can be terrestrial or freshwater in nature. Examples of nonmarine settings include rivers, lakes, glacial landscapes, and alluvial fans.

Identifying accumulation environments for gravelly sediments

Gravelly sediments are mainly composed of large, coarse-grained particles that usually require a strong force to be transported and deposited. Hence, they tend to accumulate in settings where there is enough energy to carry and deposit such particles.

Listing the nonmarine settings with gravel accumulation

The nonmarine settings where gravelly sediments often accumulate include: 1. Rivers: Fast-flowing rivers, particularly in steeper landscapes or during flood events, can transport and deposit gravels along the riverbed and the riverbanks. It is common to find gravel bars in rivers that experience high flow rates or strong currents. 2. Alluvial fans: These are fan-shaped depositional systems that form when rivers flow from a high-energy environment like a mountainous terrain into a lower-energy environment, such as a valley or a plain. The sudden decrease in the flow energy results in the deposition of coarse sediments, including gravel. 3. Glacial landscapes: Glaciers are large, slow-moving masses of ice that transport and deposit sediments as they advance and retreat. Meltwater streams flowing from glaciers can also transport gravel, depositing it at the glacier's edge or along the stream channel, forming features such as glacial moraines and outwash plains. 4. Landslides and debris flow deposits: Sudden mass movements of rocks and sediments down a slope can also lead to the accumulation of gravelly sediments. These deposits may quickly accumulate at the base of a steep slope or within a drainage channel. In conclusion, gravelly sediments often accumulate in nonmarine settings such as fast-flowing rivers, alluvial fans, glacial landscapes, and areas prone to landslides and debris flows. These locations experience enough energy to transport and deposit coarse-grained particles, resulting in the formation of gravelly sediments.