﻿380 Correspondence — Mr. W. T. Aveline — Prof. Nicholson. 



have always found it rather difficult to prove to a student that the 

 Lower and Upper Carboniferous beds really belong to one formation 

 at all, so great ia the contrast between the " essentially " marine 

 aspect of the lower, and the essentially lacustrine aspect of the 

 upper division. If this be so, is it not "philosophical" to suppose 

 that there is a middle group, between these extremes, " essentially " 

 marine, yet less oceanic than the lower stage of the Mountain 

 Limestone ? 



Meanwhile, allow me to ask my colleague to defer his opinion on 

 the views I have stated in my paper till he has had an opportunity 

 of reading it. Edward Hull. 



GEOLoaicAL Survey of Ireland, 

 Office, 14, Smne-street, JDublin. 



THE EELATION OF THE PERMIAN TO THE TRIAS. 



SiK, — Mr. Irving appears to have quite mistaken the purport of 

 my communication on the relation of the Permian to the Trias in the 

 neighbourhood of Nottingham.^ I understood it had been stated by 

 geologists of Nottingham, that not only a perfect conformity existed 

 between the Permian and the New Ked Sandstone near that town, 

 but there was a passage upwards from one formation into the other. 



I merely wrote to say this could not be, for the reasons I gave. 

 But I never intended to imply there was not a general conformity 

 between the two formations, for this general conformity must be 

 apparent to any one on looking at a good geological map, whereon 

 these formations are laid down. Neither did I intend it to be under- 

 stood that I considered that the break between the Permian and the 

 New Bed Sandstone was greater than between some of the sub- 

 divisions of these formations. As, for instance, the break between 

 the Middle Marls and Lov/er Magnesian Limestone of the Permian, 

 or that between the Keuper and the Bunter of the Trias. I gave no 

 opinion one way or the other on these points. 



The point of my communication was this. The relation of the 

 Permian to the Trias I considered an important problem yet to be 

 worked out. If a perfect passage from the one up into the other 

 was found, it would go far to settle the question. As far as I know, 

 that passage has not been found, and, I contend, it does not exist in 

 the neighbourhood of Nottingham. 



Some personal remarks in Mr. Irving's communication I shall not 

 reply to, they have nothing to do with the question, and were wholly 

 uncalled for. I do not consider the pages of a scientific magazine 

 the place for that kind of bantering. W. Talbot Aveline. 



HURONIAN VOLCANIC ROCES. 

 Sir, — In an able paper in your last issue, Mr. G-eorge M. Dawson 

 publishes the results of his study of the " Porphyrite Formation " 

 of British Columbia, and applies these results to the explanation of 

 the origin of the Huronian series of Eastern North America. I am 

 particularly pleased to find so good an observer as Mr. Dawson^ not 

 1 Geol. Mag. Dec. II. Vol. IV. p. 155* 



