A student made a model of a river in a sandbox. A pile of sand represents soil and bits of rock in the riverbed. Water
pouring from a hose represents river water as it flows
downhill.
Which two characteristics are limitations of the student's model?

Which of the following natural processes is most likely to support the formation of an underwater sinkhole? a pollution buildup from deposited minerals b limestone cave collapsing due to changes in sea level c erosion of large amounts of sand moved by ocean waves d oxidation of rock formed by chemical weathering