T. Mellaril Reach— On the Lower Trias. 263 



considerable demand upon me, and in the slang of the day is what 

 is called " a big order." I am not even prepared to say that there 

 was then an Atlantic Ocean in the sense that we understand it now. 



The possibilities of the physical geography of the period are so 

 gr-eat that I see no difficulty in the origin of a tidal wave in an 

 open ocean, and its propagation through the embaymentsor channels 

 in which I suggest the British Trias was laid down. Even in the 

 North of Ireland, in the neighbourhood of Carrickfergus on Belfast 

 Lough, the Trias is estimated at 2000 feet thick. 1 On the other 

 hand, on Slieve-Gallion-Carn, west of Lough Neagh, the Keuper is 

 found at an altitude of 1200 feet above the level of the sea. 2 



How can we in view of such facts as these aver that the English 

 Trias was laid down in a basin with shallow entrances ? On the 

 other hand, as I pointed out in my original paper read before the 

 British Association (Geol. Mag. December, 1889), there are the 

 possibilities of the extension of the Trias to the eastward under 

 the newer rocks. 



We are dealing only with remnants ; we have not materials now 

 to reconstruct the physical geography of the past with any degree 

 of accuracy ; but we know enough of the manner of occurrence and 

 extension of the Trias, of which the Bunter is one phase, to make 

 it difficult, for me at all events, to see how its distribution can be 

 explained by river action. 



I devoted a fortnight last summer to an examination of the Trias 

 of the Vale of Clwyd. At none of the sections I visited, and I saw 

 most, could I detect the presence of local materials unless it were 

 some of the marly material binding the grains. There were no 

 pebbles, either quartzite or otherwise, in the sandstones which are 

 considered to be Lower Bunter, but much persistent current bedding. 

 This crux is explained by tidal action, which in a cul-de-sac would 

 have less force than in the channel (now occupied by the peninsula 

 of Wirral) between the mountains of Flintshire and the Carboniferous 

 hills of Lancashire, forming a communication between the Triassic 

 area covered by the Irish Sea and that of the Midlands. It is on 

 these stream lines that the greatest development of the pebbles of 

 the Bunter of Lancashire and Cheshire occur. 



Prof. Bonney naturally lays great stress upon his identification of 

 some of the pebbles of the Trias with those of the Highland rocks. 



While giving due weight to his opinion on this point, such identi- 

 fications can scarcely be put in the category of absolute certainties. 



There is also another explanation of their presence volunteered by 

 Mr. Jukes-Browne, who suggests that they may be only indirectly 

 derivative from the Western Highlands of Scotland, even if that 

 were their original home. It is the increase in the number of and 

 size of the pebbles towards the Midland Counties that makes it 

 difficult to conceive that they came from the North. 



1 Kinahan's Manual of the Geology of Ireland, p. 138. 

 - Ibid. p. 141. 



