lake is a mean of sedimentary stone
sedimentary is rock. arenaceous_rock is sedimentary_rock. shale is clastic_sedimentary_rock. rock is large_rough_stone. limestone is sedimentary_rock. clastic_sedimentary_rock is sedimentary_rock. sedimentary_rock is rock. slate is sedimentary_rock. shale is sedimentary_rock. sedimentary_rock is stone.