Topsoil, which is the upper layer of the soil, is high in organic matter, fertility, and soil life. Generally, the wooded area would contain more decomposed dead plants which would contribute to making the upper layer of the soil darker compared to the sandy playing field. Though the parent material is the starting point for most soil development and the color of the soil could be attributed to the type of rock particles that weathered to form the soil. However, the darker soil in the question above indicates a greater percentage of organic matter has finished the process of breaking down into humus.
While erosion could be aided generally by the soil texture and structure. Erosion could easily take place at the sandy playing field than it would at the wooded area of the campus due to the soil compactness. The coarser the soil texture the smaller is the resistance of the soil to erosion.
Immigrants are willing to do the jobs that Americans won't do, for wages that American's would not accept. They take the jobs that Americans don't want.
