Science Olympiad Dynamic Planet Practice Test

What type of sediment fills a foreland basin in its early stages?

1. Terrestrial deposits

2. Marine flysch

3. Volcanic ash

4. Glacial till

The correct answer is: Marine flysch

In the early stages of a foreland basin's development, it is primarily filled with marine flysch. A foreland basin is a sedimentary basin that forms adjacent to a mountain range, typically as a result of tectonic activity associated with the collision of tectonic plates. As these plates converge, they create compressional forces that lead to subsidence in the area adjacent to the mountain range, allowing for the accumulation of sediments. Marine flysch consists of alternating layers of sandstone and shale, deposited in a deep marine environment. As the land is uplifted and eroded, sediments from the eroded mountains are transported into the basin, but initially, the marine environment remains prominent. This setting allows fine-grained sediments to settle out in a relatively deep, low-energy marine environment, creating the characteristic flysch deposits. In contrast, terrestrial deposits typically occur in environments where sedimentation is dominated by river systems or floodplains, which is not the predominant habitat during the initial stages of a foreland basin. Volcanic ash deposits are more localized events related to volcanic eruptions and do not specifically correlate with the characteristics of a foreland basin. Similarly, glacial till is associated with glacial environments and is not representative of the sediment types found in