148 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



direct attention. These fractures, contortions, and adhesions, 

 appear to be the effect of violent mechanical action and of heat. 



2. On the Origin of the Gypseous and Saliferous Marls of 

 the New Red Sandstone. By the Rev. D. Williams, M. A., 

 F.G.S. 



For years past I have had great difficulty in accounting for the 

 marls of the new red sandstone, and as none of the explanations 

 yet given appear to me sufficient, or satisfactorily account for the 

 absence of molluscous and zoophytous remains in these beds, and 

 still less for that of the numerous plants entombed above and 

 below them, I propose in the following observations to attempt to 

 explain these phenomena, in the hope, to use the words of Sir 

 H. Delabeche, of arriving at the " knowledge of the true causes 

 which have produced" the remarkable aggregates in question. In 

 examining the district of Bleadon with a view to account for the 

 phenomena of trap rocks presented in the railway cutting*, I 

 observed in the superficial coating of soil on the northern flank 

 of the hill above Weston-super-Mare, such abundant fragments 

 of vesicular *trap, some of them having the aspect of recent volcanic 

 scoriae, others containing spherical kernels of decomposing cal- 

 careous spar and haematitic iron, that I entertained no doubt 

 whatever that I was standing on a dyke of ancient lava. The 

 occurrence of these fragments for about seventy-five yards, in an 

 east and west direction, indicated its strike, and rendered [it 

 probable that the same appearance would recur in the neigh- 

 bouring coast cliffs. Those brown, strange-looking rocks, therefore, 

 with whose aspect I had been long familiar, were volcanic ag- 

 gregates, and were, in fact, two of the most interesting and in- 

 structive of the large number which had fallen under my notice. 



These trap rocks are perfectly distinct from each other, and the 

 nether one abuts so closely upon the road which forms the common 

 approach to the coast below the cliffs, that no geologist passing could 

 fail to see it, — indeed, could scarcely avoid touching it ; though, like 

 myself, every one had hitherto failed to remark upon it. In truth, 

 the lower trap so intimately resembles a brown sandstone, and the 

 upper one has so much the aspect of a mass of the ordinary red 

 marl with imbedded pebbles, and, at the most accessible approach, 

 is for the most part so truly a red marl, that the circumstance of 

 its having hitherto escaped notice is not surprising. 



Every bed in the series is, however, so unequivocally disclosed, 

 and so readily accessible along the shore, that no doubt whatever 

 can be entertained of their several positions. I propose to describe 

 them briefly in ascending order, as seen in the subjoined section. 



* See ante, p. 47. 



