The vast group of rock systems which constituted the outer crust of the world during the life-dawn or Proterozoic era does not now appear at many points on the earth’s surface. And when it does emerge from below all the accumulations of subsequent ages, there will be found only the fossil remains of vegetable and early primitive animal life. Some of these older water-deposited rocks are commingled with subsequent layers, and sometimes they yield fossil remains of some of the earlier forms of vegetable life, while on the topmost layers occasionally may be found some of the more primitive forms of the early marine-animal organisms. In many places these oldest stratified rock layers, bearing the fossils of the early marine life, both animal and vegetable, may be found directly on top of the older undifferentiated stone.
Posted on: Sat, 09 Nov 2013 20:12:39 +0000
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