sentences: limestone is a kind of sedimentary rock & shale is a kind of sedimentary rock ->  shale and limestone are different kinds of sedimentary rock  shale and limestone are different kinds of sedimentary rock & environments changing can cause layers of rock that are on top of each other to be of different kind & a layer of shale is on top of a layer of limestone -> environments changing causes the shale and limestone to be on top of each other