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.
The type of plate boundary least likely to have volcanoes. subduction zone; ridge or spreading center; transform fault. Reversals of the Earth's magnetic field. cause sea-floor spreading; produce stripe patterns in the magnetism of ocean-floor rocks; cause orogenies; are responsible for subduction. Hot spots. produce tracks as the plates move over them