SANDSTONE QUARRIES. 113 



At the Cape of Good Hope there is a sandstone forma- 

 tion some 2,000 feet thick, which has evidently been affected 

 in different degrees by heat, for in some parts it is stained 

 red, brown, or yellow, by iron, in others it is perfectly white, 

 as the red sand in a furnace becomes, and in others it is as 

 compact as quartz. 



There are in Great Britain some thirty well-known sand- 

 stone quarries of different qualities and colours, which 

 supply large quantities of stone. Of ancient sandstone 

 buildings in this country there are the abbeys of Tintern, 

 Whitby, Rivaulx, the cathedrals of Ripon and Durham, and 

 churches in Newcastle, Derby, Shrewsbury, Ludlow,and other 

 places too numerous to specify. All these, and many others, 

 some of them several hundred years old, are built of that 

 which once was merely sand on the sea-shore, and as not a 

 few of them have in great part crumbled away and are still 

 crumbling, much of the stone will, probably, in time, return 

 to the sea-shore again. 



So much for the sand ; and now for the mud, which, 

 though carried farther out to sea before it is deposited, is 

 seldom dropped more than two hundred miles from the 

 coast. In a tideless sea or gulf it is deposited close in shore, 

 or even at the mouth of the river, as witness the Nile delta, 

 and the mud flats on the coast of Nova Scotia, which are 

 derived from the neighbouring cliffs of shale and sandstone, 

 the sediment being deposited tide after tide in layers, some 

 of them as much as one-tenth of an inch thick, but generally 

 much thinner. 



The wide plains and low plateaux of Western Russia 

 have evidently been similarly formed of mud and sand ; but 



