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Rock Face: The angle of dip is measured with a clinometer and is stated in degrees. The "strike" of a rock is the direction in which the face of its bedding plane lies - this is given as a compass direction. Strike and dip together measure the attitude of a formation. The attitude of a rock provides one of the most reliable indications of the sub-surface structure of a particular region.The movement of the earth's crust may carry the rock as much as 700km (454 miles) below the surface. Here the temperature and pressure will be even higher and the rock will begin to melt. Molten rock is lighter than solid rock and it will begin to rise up through the overlying rock towards the surface. If it reaches the surface as a lava flow it will immediately be ready for weathering and erosion and the start of a new cycle. More often the molten rock solidifies underground and then all the rock above it must be eroded away before it can begin the cycle again.
Gibraltar has been a familiar landmark to generations of steamei travelers but this report shall view it in terms of air travel, for Gibraltai Airways, linking the Rock with Seville, Malaga and Tangier, and BEA, providing a daily service from and to London, have made such a viewing very practical. The airport, by the way, is in the lee of that stupendous 1400-foot rock face which the Prudential Life Insurance Company made famous in its advertising at least fifty years ago. From the steamer's deck you don't see that Gibraltar at all. You see a crouching lion of sorts. |
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