BKECKNOCKSBXRE AND EAST GLAMOKGANSHIKE. 



45 



Fig. 2.— Section of Boulder-clay and Flint-bearing Gravel, Ely 

 Valley, St. George's, near Cardiff. (Scale, 1 inch to 6 feet.) 



Winnowed Boulder-clay. 



Boulder-clay. 



Coarse compact gravel with Chalk flints. 



...Sand and plant-remains. 



> Coarse gravel with Chalk flints. 



'"Sand and plant-remains. 

 ..Coarse gravel: Chalk flints, limonite. 

 ...Sand, fine gravel, and plant-remains. 



> Firmly cemented pebble-gravel : Chalk flints. 



6 'fi^^lf^^^^^m I Fine S ravel and sand ' ^i* 11 la y er s of limonite, plant- 

 remains, and Chalk flints. 



Well-rounded pebbles of Carboniferous Sandstone, 

 4 in. in diameter, bedded in ferruginous sand. 



Height above sea-level about 80 feet. 



Gravel composed of pebbles of Carboniferous Sandstone, Carboniferous Lime- 

 stone, Old Red Sandstone, Old Eed Conglomerate, Millstone Grit, and 

 Triassic Sandstone,- the largest being 8 inches in diameter and only par- 

 tially rounded. About 95 per cent, of the pebbles are Carboniferous 

 Sandstone. Besides pebbles of quartz and Lydian stone, one of veinstone 

 and another of quartz-porphyry have been found associated with the Chalk 

 flints. 



2. Boulder-clay occurs in patches filling depressions over the whole 

 area to which this paper refers. In most places it exhibits the 

 same characteristics of a stiff, compact clay, varying in colour and 

 composition according to the nature of the substratum. The in- 

 cluded stones vary in size from mere pebbles to blocks 4 or 5 

 feet in diameter. Nearly all the stones in the Boulder-clay are 

 smoothed, rounded, and often intensely glaciated, principally in the 

 direction of their longer axes. Its thickness ranges from about 100 

 feet at Pont Sarn in the Taff-fechan valley, to 30 feet at St. 

 Eagans in the Ely valley. Its height above the sea-level varies 

 from above 1200 feet at Dowlais Top to 20 feet in the Ely valley, 

 at St. Fagans. The Ely valley Boulder-clay is distinguished from 

 that of the coal -basin and south Brecknockshire by containing Chalk 

 flints. These also underlie the Boulder-clay, as already stated, at 

 St. George's in the Ely valley. 



