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masses of the miilille and upper Old Reds, and these again are surmounted by 

 the Mountain Limestone and the Millstone Grit. 



The Mountain Limestone is beloved by the paleontologist for its 

 picturesque scenery, its caves full of the remains of wild animals that once 

 roamed over the hill sides of ancient England, and the number of fossil shells, 

 and fishes, that once frequented its seas. The botanist, too, rejoices in the rare 

 and beautiful plants no\irislied in its fissures and on its slopes ; while the 

 archasologist marks many a cromlech, camp, and dyke ; and the historian lingers 

 amid the memories of many a hard-fought battle, and many a struggle for 

 independance fought out to the death among its ravines and dingles. But for the 

 physical geologist there is a tale of waste and denudation, and former extension, 

 told by the crags and outliers of the Mountain Limestone and MiUstone Grit, 

 which no true eye and head can miss. 



It is impossible to enter much into detail in an addi'ess of this kind ; and 

 the utmost I can do is to give to the members of this society a few examples of 

 the points I wish to draw attention to on this occasion, namely, the upheavals 

 and subsidences among the rocks we visit to-day ; and the denudation they have 

 undergone. 



I do not know whether any here are infected with the denudation mania, 

 and imagine that rain and rivers have been the only agents which have effected 

 the construction of the country as we now see it. If so, I recommend those that 

 are thus afflicted to visit the noble Fans of Caermarthen, and examine the position 

 of the Old Red conglomerate on the heights of the Fan-sir-gaer and see it dipping 

 on its strike to the westward under the carboniferous limestone, within a short 

 walk. Then let the student take the hill side w^lk, and visit the down-throw 

 of the mountain limestone at Castel-cerrig Cennen. The Old Red conglomerate, 

 which on the Fan-su-gaer occupies the crest of the hill, at Cerrig Cennen is 

 thrown down to the bottom of the valley, and above it rises the wonderful 

 dislocated mass of limestone, on which stands the ancient fortress of a Norman 

 chief. Neither rain or river washed this limestone peak to its position, 

 although the little Cennen has had its share in after denudation. 



It is only of late that geologists have begun to unravel the history of pre- 

 glacial, glacial, and post-glacial periods, and it is necessary to collect all the 

 evidence we can respecting geological changes that occurred during all these 

 periods, if we would understand the origin of the scenery around us. The earth 

 has undergone dislocations and upheavals, downthrows and subsidences, and 

 there were hills and valleys in pre-glacial times, as there are now ; and rain and 

 rivers did their work with other atmospheric agencies, and for ages moulded the 

 old pre-glacial continents. The influences of intense frosts, glaciers, and ice 

 sheets, must also be borne in mind as having moulded this old land for unnumbered 

 ages. The glacial submergence ensued, and with it came other forms of 

 denudation. The post-glacial emergence succeeds, and for thousands of years 

 gi'eat cold was the condition of the British Isles, cold more intense than we ever 



