sentences: in the formation of sedimentary rock , erosion is the first stage
docs: sedimentary is rock. geological_formation is layer. arenaceous_rock is sedimentary_rock. shale is clastic_sedimentary_rock. sedimentary_clay is soil. erosion is geological_process. clastic_sedimentary_rock is sedimentary_rock. sedimentary_rock is rock. shale is sedimentary_rock. sedimentary_rock is stone.