A student placed some clean rocks in a clear plastic jar. The jar was filled with clean water and covered with a lid. The student then shook the jar up for five minutes. The student noted that smaller pieces had broken off some of the rocks and that there was a fine grit on the bottom of the jar. Which change of Earth's surface was the student modeling? * A. mechanical weathering B. chemical weathering C. erosion of sediments D. forming deltas