182 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 12, 
Fig. 2.—Section of Dolomitic Conglomerate in the new road leading 
from the Hotwells to Clifton and Durdham Downs, showing pas- 
sage from heavy massive Conglomerate into fine-grained Sand- 
stone. 
Soe 
Walt wz [Bind Gr O4 
eee rond S00 5s 
==N XS 
i CRE 
River KC ey PON 6222S 
S44 DADO NES 
This breccia largely oceupies the country between Barry and Sully 
Islands and Llandaff, and between the latter place and Llanharry, 
Coyty, and Pyle, fringing the limestone downs of St. Nicholas, St. 
Donats, and Nottage, and is, in extent, nearly equal to that of the 
Mendip range; indeed, physically, these two masses of old land on 
either side of the Severn were, and are now, one, being divided only 
by a deep depression in the Carboniferous Limestone, now occupied 
by the waters of the Severn. The strike of the submerged lime- 
stone is still indicated by three patches at Barry Island, the Wolves’ 
Rock, and the two islands termed the Flat and Steep Holmes, which 
now evidence that the ridge of high paleeozoic land was once con- 
tinuous to the peninsula of Gower and Menevia, and onwards, under 
the St. George’s Channel, to the south of Ireland. This axis alone 
is determinable for 150 miles, over nearly 80 of which the conglo- 
merate occurs more or less, covering much of the once-exposed 
masses and flanks of the older rocks. 
In the Bristol area, however, as noticed by Buckland and Cony- 
beare *, the breccia is chiefly composed of the débris of the rocks 
on which the conglomerate rests; and the fragments vary in size 
from an inch to three or four feet in diameter, many of the larger 
boulders weighing from one to three tons each. 
The conglomerate of the Quantock Hills (of the same age) is 
constructed entirely of the Devonian slates and limestones of which 
these hills are composed; so with the breccias at Milverton, east of 
Wiveliscombe, and in the vale of Stogumber, between the Quantock 
Hills and the Exmoor. Porlock and Luckham valleys, although so 
completely isolated and shut in and to the north of Exmoor, exhibit 
conglomerates of the same age, and have the same physical aspects. 
So also at Brandon Hill (Bristol), where pebbles of quartzose mill- 
stone grit only form the mass. On the left bank of the Avon, opposite 
Cook’s Folly, the conglomerate conceals the subjacent highly inclined 
beds of Old Red Sandstone, and is there also entirely derived from 
the rock upon which it rests. 
* Trans. Geol. Soc. vol. i. 
