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.
Sea-floor spreading occurs where oceanic plates are diverging from one another. Plates are huge slabs into which the crust as well as the upper part of the mantle (the intermediate zones between the Earthâs crust and core) is divided.As the plates move apart, the rocks break and form a crack between the plates.agma is a very hot, molten rock which is formed within the earth by partial melting of the mantle. As a result, the age of the rocks increases as one move away from the rift-zone (place where the earthâs crust is pulled apart). The mid-oceanic ridge is the primary site for sea-floor spreading.