268 EFFECT OF RAINS, UIVERS, AND TIDES. 



Thus the spoils of one rocky formation arc borne from their native soil, 

 and are strewed over the surface of other kinds of rock of a totally dil- 

 ferent character. The fragments of the granite, gneiss, and slate rocks 

 of the high lands are scattered over the old red sand-stones which lie at 

 a lower level — and those of the blue lime-stone mountains over the mill- 

 stone grits, the coal measures, and the new red sand-stones, which stretch 

 away from their feet. 



2°. But the effects produced by this natural cause, though .they may 

 be judged of in kind, can never be estimated in degree by what we per- 

 ceive in our own temperate climates — in our country of small rivers and 

 gentle rains. How must such effects exceed in magnitude, in districts 

 where, — as in the Ghauts, that separate the level land of the Malabar 

 coast (the Concan) from the high table-land of the Deccan, — 120 inches 

 of rain occasionally fall in a single month, and 240 inches or 20 feet, on 

 an average, every year from June to September ! And to what vast 

 distances must materials be transported by great rivers, such as the Mis- 

 sissippi, the River of Amazons, the Ganges, and the Indus, which main- 

 tain a course of thousands of miles, before they empty themselves into 

 ihe sea ? What necessary connection can the deposits of mud and sand 

 which yearly collect at the mouths and in the places overflowed by the 

 waters of these great rivers, have with the nature of the rocks on which 

 these transported materials may happen to rest? 



3°. But the constant motion of the waters of the sea washes down 

 the cliffs on one coast, and carries away their ruins to be deposited, either 

 in its own depths, or along other more sheltered shores. Hence sand 

 banks accumulate — as in the centre of our own North Sea: or the land 

 gains upon the water in one spot what it loses in another — as may be 

 seen both on the shores of our own island, and on the opposite coasts of 

 Germany and France. 



What necessary relation can the soils thus gained from the sea have 

 to the rocks on which they rest? Suppose the bottom of the North Sea 

 to become dry land, what necessary mineral relation would then exist 

 between the soils which would gradually be formed on its hundreds of 

 square miles of sand-banks, and the rocks on which those sand-banks 

 immediately repose? 



4°. Again, the sea, in general, carries with it and deposhs in its owk 

 bosom the finest particles of clay, lime, and other earthy matters, and 

 leaves along its shores accumulations of fine siliceous sand. This sand, 

 when dry, the sea winds bear before them and strew over the land, fomi- 

 ing sand hills and downs, sometimes of considerable height and of great 

 extent. Such ^re to be seen here and there, in our own islands, but on 

 the Eastern shores of the Bay of Biscay, and on the coasts of Jutland, — 

 both exposed to violent sea winds, — they occur over much larger areas. 

 Before these winds the light^sands are continually drifting, and, year by 

 year, advance further and further into the country, gradually driving 

 lakes before them, swallowing up forests and cultivated fields, with the 

 houses of the cultivators, and burying alike the fertile soils and the rock* 

 from which they were originally derived. [In the Landes, the ad- 

 vance of the downs is estimated at 66 to 70 feet every year.] 



You have all read of. the fearful sands of the African deserts, and of 



