In 1968 the average salary of men teachers in maintained schools in England and Wales was Â£1,646. I estimate that the last two pay settlements have raised this figure to about Â£1,880. The comparable figure at 31st March, 1963, was Â£1,244.
Two main tectonic structures are spreading centers and subduction zones. Spreading centers occur at the boundary between two plates that are moving apart, called divergent plate boundaries. Here the plate motion opens a gap between the plates and magma from the mantle rises up through it.
SPREADING CENTER VOLCANISM. Spreading center volcanism occurs at the site of mid-oceanic ridges, where two plates diverge from one another. As the plates are pulled apart, hot asthenosphere rises upward to fill voids of the extended lithosphere. The rise of this hot mantle provides thermal buoyancy to the ridge area and this is the reason that they stand as high ridges in the center of ocean basins.