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old Red which must originally have overlaid the Silurian Rocks. Imagine a slice cut 

 from the top of an onion. If you wish to compute the thickness of the part cut off, 

 you may very readily do so by means of the thickness of the coats remaining, and this 

 will give you a clear idea of the data that the Woolhope Valley affords for computing 

 the amount of its denudation. 



The Malvern range affords an excellent example of volcanic action. The force which 

 probably threw up the Silurian rocks through the Old Red Sandstone at Usk and Wool- 

 hope found a vent at Malvern, and poured forth in a fluid state the rocks which 

 form so beautiful an outline in the scenery of this county and Worcestershire. 



The Clee hill Coalfield is again a most interesting subject of study. It is perhaps 

 the highest in England above the sea level, and there is reason to suppose that it was 

 absolutely lifted upwards by volcanic action. Dislocations having occurred from this 

 violent action, the molten Basalt has passed upwards through the crevices thus formed, 

 and has overspread the entire coal formation. 



There is also an exceedingly interesting coalfield at Leebotwood, near Church 

 Stretton. It is, I believe, the only example where the coal formation rests, immediately, 

 on the Cambrian rocks. This fact has been overlooked by Sir R. Murchison in hia 

 "Siluria." 



To come now to the geology of this immediate district. Let me draw your atten- 

 tion to the remarkable eruption of the Stanner rocks, on which we now stand, and which 

 form so prominent an object in the landscape. This rock is charged with Hypersthene, 

 and is the only rock in the British isles, with the exception of one at Skye, which con- 

 tains this mineral in any appreciable quantity. Ordinary typical granite is composed 

 of quartz, mica, and felspar. The Syenitic granite of Hunter-hill, which you see before 

 you, and also of that of the Malvern range, is composed of quartz, felspar, and 

 hornblende, whereas the hsrpersthene granite of Stanner is composed of quartz, mica, 

 and hypersthene. Hypersthene is a member of the hornblende family, and is so called 

 from its power of resisting acids, as compared with augite, to which it is closely related. 

 It has a vitreo-resinous lustre and a brown or greyish green colour, passing into black. 

 Hypersthene is a ferrosilicate of magnesia, with only traces of alumina and lime, and in 

 this it differs also from augite, which contains as much as about 20 per cent, of lime. 



Many persons think that the age of geological discovery has passed away ; yet in 

 this very district, at a Woolhope club meeting held on the 29th July, 1856, the carapace, 

 swimming feet, pincers, and some other portions of a gigantic lobster, some six or 

 seven feet long, were discovered in the quarry of Downton sandstone on Bradnor-hill, 

 which you have had the advantage this morning of visiting under the guidance of Mr. 

 Banks. This distinguished member of our club had previously discovered, and worked 

 out with much care and perseverance, several parts of an allied crnstacean, and on the 

 day to which I allude Mr. Salter, who was present at the meeting, drew the animal 

 full size from the portions obtained, restoring by outline the missing parts. Mr. Salter, 

 in honour of the discoverer, gave to this huge lobster the name of the Pterygotus Banksii 

 (hear). Whether the temperature of the sea in which the creature lived may have been 

 greater than which at present prevails around the British isles, I will leave to the specu- 

 lative and inductive geologists of the meeting. 



We found on this same day a specimen of the Pteraspis, which Mr. Banks was 

 also so fortunate as to discover, and which also bears his name. It is not necessary to 

 allude further to the fossils of the district, for Mr. Banks himself, in his address as 

 president of our club, has given us the very valuable list which is published in the 

 transactions. 



