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XXXVI. — Notices from the Minute Boohs of the Geological Society. 



1 . On the Geological Structure and PhcBnomena of the Northern Part of the Coten- 

 tin, and particularly in the immediate vicinity of Cherbourg. By the Rev. W. 

 B. Clarke, A.M., F.G.S., &c. (Read Feb. 1, 1837.) 



X HE author commences by stating, that no fact among the geological phsenomena 

 presented in both hemispheres, appears to be more clearly determined than the oc- 

 currence of granitic rocks of posterior date to deposits containing organic remains 

 of comparatively recent origin. Instances of this position, he says, are exhibited 

 on a great scale in Brittany, Normandy, and the Channel Islands, where quartz 

 rock and schists (the last containing, as will be subsequently shown, vegetable 

 and testaceous remains) have been disturbed by granite and the protrusion of the 

 latter effected by trap ; and he refers to Humboldt's allusion to the Cotentin in 

 proof of the intimate connexion of quartz rock, schist (occasionally connected 

 with limestone), and granite*; also to the memoir of M. Alex. Brongniart on the 

 Cotentin t, with the note by M. d'Omalius d'Halloy on Brittany J ; likewise to 

 Mr. De la Beche's paper on Calvados and La Manche § ; as well as the memoirs 

 of Professor Sedgwick and Mr. Murchison on Cornwall and Devonshire |1, &c., for 

 the occurrence of the same series of rocks under precisely similar conditions in 

 each district *1[, and for evidences that the granite was protruded at a comparatively 

 recent period, not only altering the characters of the associated sedimentary strata, 

 but elevating the rocks en masse to their present positions. With respect to the 

 phsenomena exhibited in the Channel Islands, Mr. Clarke says, that the granitic, 

 schistose and quartz rocks are exactly in the range of the analogous formations of 

 the Cotentin ; that the trap of Sercq occurs intermediate to the other deposits, as 

 in the Cotentin ; and that to the protrusion of the trap the actual position of the 

 granite, slates and quartz rock must be assigned. 



* ' Sur le Gisemenl des Roches,' pp. 106, 145, 1823, 



t Journal des Mines, tome xxxv. p. 109 et seq., 1814. J Ibid., p. 112, note 2. 



§ Geol. Trans., Second Series, vol. i. p. 73 et seq., 1822. 



II Prof. Sedgwick, on the Structure of large Mineral Masses, Geol. Trans., Second Series, vol. iii. 

 p. 484 et seq. Prof. Sedgwick and Mr. Murchison on Devonshire, Report of the British Association 

 for 1836. 



f For instances out of Europe, reference is made to Capt. Burne's remarks on Hindoo Kosh, Geol. 

 Trans., vol. iii. p. 492 ; and Humboldt's ' Gisement des Roches,' pp. 103 et seq., p. 143 et seq. 



