Plate Tectonics Plate Tectonics is theory of global tectonics that has served as the master key in modern geology for understanding the structure, history, and dynamics of the earth's crust. The theory is based on the observation that the earth's solid crust is broken up into a dozen semirigid plates. The boundaries of these plates are zones of tectonic activity, where earthquakes and volcanic eruptions tend to occur. Plate Tectonics also are the cause of …
showed first 75 words of 485 total

showed last 75 words of 485 total
…off the ridge, calcareous sedimentation, caused by microorganisms, is found. Clays and chert (silica rock) occur in deeper parts. On the continental margins of mature oceans, the basal clastic wedge may be succeeded, if the climate is appropriate, by a carbonate platform, such as the Bahama Banks off the eastern United States and the Great Barrier Reef off northeastern Australia. Turbidity currents flow down the continental slope and deposit terrigenous sediments in the deeper water