504 F. T. 8. Houghton — Olivine Gabbro from Cornwall. 



Omitting from consideration the "Lower Permian Sandstone," the 

 true horizon of which seems doubtful, we still find a very dissimilar 

 grouping of the Permians on the two sides of the Pennine Chain. 

 In Lancashire and Cheshire we look in vain for any deposit answer- 

 ing to the highly characteristic Marl-slates of the North-east of 

 England, nor do we find any considerable masses of dolomite com- 

 parable with those of Yorkshire and Durham. From Notts to 

 Northumberland the Marl-slates, Magnesian Limestone, and Upper 

 Marls are severally distributed, but on passing across England from 

 Notts to Lancashire — a much less horizontal distance — we find that 

 we cannot positively recognize one of these members of the Zechstein. 

 This marked dissimilarity is in part at least to be accounted for by 

 the presence of an intervening land-barrier — the Pennine Chain. 



We may then, I think, without hesitation, conclude that the 

 elevation of the Pennine Chain took place before the commencement 

 of the Permian epoch, or at any rate prior to the deposition of the 

 Permian rocks of the North of England. 



I have already called attention to some of the results of the 

 elevation of this important range. Its influence on the distribution 

 of the rock masses of the neighbourhood, which began in early 

 Permian times, persisted into the Keuper epoch. Having in Pre- 

 Permian times acquired the elevation and stability of an arch, this 

 great and complex anticlinal still maintains that relative superiority 

 to the surrounding country that has justly earned for it the epithet 

 of the " Backbone of England." Though marine denudation has 

 planed away its top, while subaerial decay has cut deeply into its 

 framework, the great hardness and extreme durability of its more 

 axial rocks has enabled this ancient anticlinal to resist these agents 

 of destruction so successfully that it still forms a broad elevated 

 tract of country, while rearing its loftier peaks from two to three 

 thousand feet above the sea. 



V. — Note on an Olivine Gabbro (Forellenstein) from Cornwall. 



By F. T. S. Houghton, B.A., 

 Scholar of St. John's College, Cambridge. 



TN Quart. Journ. Geol. Soc. 1877, pp. 906, et seq., Prof. Bonney 

 describes a Gabbro from Coverack, on the eastern coast of the 

 Lizard peninsula, which he remarks bears, macroscopically and 

 microscopically, a close resemblance to the Forellenstein of Volpers- 

 dorf. In order to investigate further the nature of the rock, I made, 

 at his suggestion, an analysis of it. The piece selected had proved 

 on microscopic examination to be almost free from pyroxenic con- 

 stituents. No. I. was decomposed by fusion with alkalies. No. II. 

 by hydrochloric acid. The residue in this case was white, and 

 probably consisted of undecomposed felspar, showing that at any 

 rate it was not all anorthite. No. III. is an analysis of the Volpers- 

 dorf rock quoted by Zirkel (Lehrb. der Petrog. ii. 139). 



