The appalachian mountains, which extend from canada to alabama, were much taller in the past than they are today. which of the following two processes are most responsible for the decrease in the height of the appalachian mountains? a weathering and erosion b sedimentation and flooding c volcanic eruptions and landslides d tectonic collisions and earthquakes which of the following statements best explains why earthquakes occur more frequently in california than in massachusetts? * 1 point a the rock found in california is igneous, but the rock found in massachusetts is sedimentary. b california is located on the boundary of two crustal plates, but massachusetts is not. c the rock under california is soft, but the rock under massachusetts is hard. d california is located on a continental plate, but massachusetts is not. an oceanic plate has been moving over a hot spot for millions of years. what features form as a result of this motion? * 1 point a volcanoes form as lava erupts through the oceanic plate. b valleys form as the hot spot drags the oceanic plate down. c mountains form as the oceanic plate cools over the hot spot. d underground caves form as lava slowly drips beneath the oceanic plate.