sentences: glaciers moving cause scratches in rocks
docs: glacial_boulder is boulder. sagittarius has been_smeared_across_space planking is covering. high_mountains has snow_on mountains_often has snow_on martian_south_pole has carbon_dioxide_ice_cap phosphate_weathering is erosion. icebergs has broken_off_from_glaciers yellow_snow is bad_snow. sand_crack is animal_disease.