AND THE A¥ON GOEGE. 
197 
of rock, over a wide area of country, as the presence of a definite 
ravine, like the Clifton Gorge. And yet it seems to me that the 
general denudation which has removed all the Inferior Oolite, not 
to mention the newer rocks which almost certainly overlaid it, 
and nearly all the Lias, from our district, demands almost more 
of our wonder, and our faith in geological principles, than the 
special denudation which has cut for us the Avon Gorge. 
Assuredly if we must call upon an inexplicable convulsion of 
nature to explain the one, we must in like manner call upon a 
yet more inexplicable convulsion of nature to explain the other. 
Finally we must remember that this vast system of 
denudation yet in progress has revealed to us the effects of a 
pre-Mesozoic denudation equally vast. Our limestone Downs 
and our Old Ked ridges are physical features which have been 
rather reproduced than produced by our present system of 
denudation. For long ages these ridges, carved out by the older 
denudation, lay buried beneath a load of Mesozoic rocks. To 
remove this load has been the main work of the present system 
of general denudation, while special denudation has been cutting 
those notch-like gorges, which break the continuity of the 
ancient ridges. 
Note. — I have to express my thanks to Sir Philip Miles, Sir 
Greville Smyth, and Mrs. Harford for kindly giving me permission 
to wander at will through their estates. 
The section on the Clifton Fault covers the same ground as my 
paper to be published in the May number of the Quarterly Journal 
of the Geological Society of London. 
