Ixxxii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



calling in the aid of any violent operation of nature. The strongly 

 marked false bedding of the sandstones is a proof of variable velo- 

 cities in the waters in which they were formed, such as would occur 

 in small lakes subject to increase from violent floods : the foot-prints 

 have been referred to Chelonians, Lizards, and Batrachians ; all more 

 likely to be found on the banks of lakes than on the shores of the 

 sea, and all proving the existence of land close by ; it seems there- 

 fore probable that these small deposits were formed in lakes, and in 

 that case the mountain-range across the south of Scotland must have 

 had at the time nearly the same elevation above the sea as it has at 

 present. This conclusion will leave us quite unable to fix on the 

 geological age of the sandstones, which may have been formed at any 

 period after that of the Mountain Limestone, the latest rock of which 

 they contain any fragments. Professor Harkness considers them 

 to be Permian. 



This hypothesis is bold, and deserves attention as a legitimate de- 

 duction from the ordinary effects of existing causes, as now observable, 

 though perhaps it would be better illustrated by the arrangement 

 of artificial earth-works into distinct strata than by the depositions 

 now formed under our sea- or lake-cliffs. The difficulty appears to 

 be in accounting for the periodical fall of such large quantities of 

 debris necessary to form the beds of breccia, and the alternation of 

 such beds with those of ordinary sand. Angular lumps, or even 

 patches, of breccia might be readily understood, but beds of consider- 

 able thickness continuous for many miles seem to imply an extent 

 of fall and a simultaneity and regularity of such fall over a con- 

 siderable lateral extension, not, I think, to be paralleled in nature. 

 The wearing action in lakes must necessarily be less than in the 

 sea, and the presence therefore of beds of breccia may fairly be 

 regarded a good argument for considering these formations to be 

 lacustrine. 



An Essay of Professor Harkness on the Geology of Dingle Ter- 

 ritory may be noticed here, as affording a striking illustration of the 

 folding or convolutions of strata. It is unnecessary to follow the 

 section throughout ; nor is it necessary for the present purpose to 

 discuss the question of the precise age of these Silurian strata : it 

 is sufficient to state that Professor Harkness considers it impossible 

 to assume that the two Silurian zones seen in the section, containing 

 the same fossils and mineralogically the same, are successive deposits 

 in one vast unbroken series, — a supposition which w ould have placed 

 12,000 feet of unfossiliferous strata between two fossiliferous deposits 

 having the same organic characters ; and he ascribes this interca- 

 lation of the supposed Devonian strata between the two Silurian 

 deposits to the folding back of the strata, the axis of each of 

 the great curves or convolutions having been thrown over to the 

 north, and thus induced a southern dip throughout the whole mass. 

 Another paper on the cleavage of the Devonians of the south-west 

 of Ireland has been also published by Professor Harkness and Dr. 

 Blyth in the Edinburgh New Philosophical Journal, and thus com- 

 mented upon by Mr. Sharpe. The authors give some interesting 



