Some of the characteristics upstream may be influenced by the presence of clay layers along the stream. Clay acts as a cohesive medium that is more difficult to erode. Other geologic structure may have influenced the steepened slope near the mouth of the stream. This portion of Horsepen Run runs parallel to a dipping limb of an upright syncline. Vegetation plays an important role in this area.
Vegetation reduces erosion and the quantity of sediment transported to the stream.
Additionally, trees growing on shallow bedrock have toppled over and create small dams across the streams. These dams collect sediments being transported downstream, causing the stream to aggrade locally. The response of the stream is to seek a more efficient slope by migrating. Closely tied to vegetation, climatic change can influence the characteristics of a stream over time. More or less precipitation in the region affects the hydrology.