glaciers moving cause scratches in rocks
martian_south_pole has carbon_dioxide_ice_cap sand_crack is not animal_disease. sand_crack is animal_disease. phosphate_weathering is erosion. plum has not smooth_skin martian_south_pole has not carbon_dioxide_ice_cap phosphate_weathering is not erosion. glacier is not slowly_moving_river_of_ice. icebergs has broken_off_from_glaciers icebergs has not broken_off_from_glaciers