132 The Geology of the Cluden Basin. 



the Glenburn, Shawhead. The underlying Hartfell and Birkhill 

 shales are exposed in the river gorge, while the overlying greyvvackes 

 are thrown into numerous folds. The east limb of this anticlino- 

 rum is laid bare in the Auld Water at Routen Bridge, where it is 

 generally vertical and sometimes inverted. The crest of the 

 arch is wholly removed, thus proving the immense lapse of time 

 since the contortion of the strata. The next three chapters of 

 geological story are awanting in our valley, but present in those 

 of the Annandale streams. The remainder of the Cluden basin, 

 from the church downward, belongs to an epoch vastly younger, 

 and now known as the Triassic. How long the interval may 

 have been between the elevation of the land in Silurian times and 

 its partial submergence again in the Triassic Age it is impossible 

 to say. But some idea may be gleaned when we recollect that 

 18,000 feet of sediment had been deposited elsewhere in Britain; 

 and that the insignificant graptolite of inches is replaced by 

 gigantic dinosaurs and immense lizards 20 feet long. Whenever 

 a junction of these two formations is exposed there is always a 

 marked unconformability between the old Silurian strata, tilted 

 and contorted, with abraded edges, and the overlying horizontal 

 deposit of the Trias. This younger formation is composed of 

 sandstone and breccia, and represents the sediment of an inland 

 sea reaching to Auldgirth, Collin, Cove Quarries, Carlisle, and 

 a fringe of Cumberland. This subject was ably dealt with on its 

 economic aspect by Mr Robert Boyle, of Glasgow, in a paper, 

 entitled the "New Red Sandstones of the South of Scotland," 

 which was published by the local press. The origin of the 

 breccia was also fittingly introduced a few years ago by an 

 esteemed member, Mr Watt, in a paper to this Society. Both of 

 these writers, however, classed the deposit as Permian, instead 

 of Triassic, as is now held by the highest authorities to be. At 

 Cluden Mills the breccia predominates, with five or six thin bands 

 of sandstone intercalated. Both are inclined towards the south- 

 west at a gentle angle of 7 degrees. The change of scenery 

 throughout the Nith and Cluden basins at this point is very 

 striking. The mountainous features of the Silurian uplands are 

 replaced by grassy knolls and level plains. The bare pastoral 

 hillside and moorland give place to the fertile meadows and 

 intervening ridges, with a warmer soil and earlier harvests. A 



