What did the surface of the Earth look like 250 million years ago?

Mass extinction of land and sea biodiversity 250 million years ago not simultaneous. The Great Escarpment in Karoo National Park, South Africa, looking across the Lower Karoo. Some 250 million years ago, simultaneous mass extinctions of marine and terrestrial life occurred in an event known as the End-Permian.

Answer (d) may increase or decrease porosity through dissolution or deposition;