natural weather

SEA EROSION AT PAKEFIELD, NEAR LOWESTOFT
The sea has cut away the cliff until houses—once some distance from the cliff edge—have collapsed
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the weak places in a rock or even in a brick wall are penetrated by wind and rain, and the effects of such prolonged exposure to the elements can be seen in the pictures above.
Frost has its strongest effect when porous rocks have had their cavities and cracks filled with water—for instance, after heavy rain. During severe frost the water, turning to ice, expands and exerts great pressure, widening crevices and producing ice crystals even in microscopic cavities. When it is remembered that water increases its volume by more than one-tenth in freezing, it will be seen how powerful this pressure can be. When the thaw sets in, mineral crystals, particles of rock, and even pebbles or large stones which have been loosened are dislodged by gravity, wind, or rain. Anyone who has noticed the spongy nature of a gravel path when first the thaw sets in aftei Dost will realize how much the top crust of trodden gravel has been lifted by the ice underneath. In regions of prolonged winter frosts, as in the mountains of Switzerland, the effects are not apparent until spring comes and the ice in the lower parts of the mountains melts. Then blocks of stone, which have been cut off the mountain walls by the ice, tumble into the valleys below.
2. Erosion. This word, taken literally, means ‘eating away’. It is impossible to separate erosion and weathering completely, since the sand-blast of the desert and the driving rain of a storm are eroding no less than weathering forces; but it is usual to restrict the term erosion to actions which more closely fit the exact meaning of gnawing away. Rain, running water, waves, and moving ice are the main agents of erosion. The great world problem of erosion in relation to human settlement and agriculture is dealt with separately {see Soil Erosion).
Running water erodes by the agency of particles of sand (as in a streamlet), pebbles (as at the bottom of a rather slow river), or large stones (as in the case of a vast mountain torrent). Sometimes, in swiftly running streams, large stones carve out ‘pot-holes’ even in hard rock. The sea uses stones as one of its weapons in its assault upon shores and cliffs. Storm waves hurl tons of water with enormous force against the