Which soil parent material is typically deposited by flowing streams or rivers?

Alluvium is the correct answer because it refers to the sediment that is deposited by flowing water, such as rivers and streams. As water moves through different terrains, it carries various particles, which include sand, silt, clay, and gravel. When the flow speed decreases, these sediments settle along the banks or bottom of the water body, forming alluvial deposits. This process is significant in shaping river valleys and creating fertile floodplains, which are ideal for agriculture.

In contrast, glacial till is a mixture of various particle sizes deposited directly by melting glaciers, and it typically contains a broader range of materials than just sediment carried by water. Residual material is derived from the weathering of bedrock in place, rather than being transported by water, making it distinct from alluvium. Loess refers to wind-blown silt deposits that accumulate over time, and while these can be rich and fertile, they are not associated with flowing water. Each of these materials has its specific formation and characteristics, while alluvium is primarily linked to the action of flowing streams and rivers.