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a8 SURFACE OF THE EARTH, confiderable the quantity of water, and the more mountainous the country. Thefe floods are ftill more deftrudive, when the mountain rocks are of fuch a nature, as to afford little refiftance to the impetuofity of the water; that is, when they are decompofed, loofe in their texture, or have fuch a fhape as to allow the water to ad more eafily on them. If vve compare together all thefe circum- liances, we fhall find that mountainous countries are more liable to fuffer from the effeds of floods, than low and flat countries. To this, indeed, there are exceptions, as in the cafe of granite, and other rocks that long refill the effeds of the moll powerful and violent floods. The water of thefe floods, in its progrefs to wards the lower parts of the earth, flows either into ravines, and from thefe into valleys and beds of rivers; or when it meets with no ravine, fcoops out a bed for itfelf, wherever it meets with a foft yielding rock or a flight hollow. The jundion of thefe mountain-ftreams with the river of the di- ftrid not oniy increafes its power by the addition of a confiderable quantity of water, but alfo caufes it to overflow its banks, and deluge the neighbour ing country, and thus to occafion great changes on its furface. The different loofe materials are car ried onwards to the fea, and are depolited at dif ferent diftances from the mouth of the river; and thefe are proportioned to the magnitude of the jnalfts. I he finelt or loamy parts reach the fea ; the