in terms of sedimentary rock layers on a cliff face. At the bottom are grey shales containing plant fossils and a thin layer of coal. Second, a transition to quartz sandstone which displays ripple marks in places and the grains go from mid sized, to fine grained at the top. The third layer results in more shales but they contain ancient seashells instead of plant fossils and coals. Finally, the top contains layers of grey and light brown limestones, some of which display various marine fossils, including coral. How did the environments of deposition change at thhis cliff face? What one thing may have occured to cause these changes?