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XXXIII. — On the Geology of Coalbrook Dale. 

 Bv JOSEPH PRESTVVICa Jun., F.G.S. 



[Read February 5, 1834, April 13 and 27, 1836.] 



CONTENTS. 



Introduction, p. 413. 



Extent and Physical Features of the 



District, p. 415. 

 Formations : — 



Lower Silurian Rocks, p. 418. 



Caradoc Sandstone, p. 418. 

 Upper Silurian Rocks, p. 419. 

 Wenlock Shale, p. 419. 

 Wenlock Limestone, p. 419. 



Organic Remains, p. 421. 



Ludlow Rocks, p. 422. 



Upper, p. 422. 



Middle, p. 423. 



Lower, p. 423. 



Old Red Sandstone, p. 424. 



Formations : — 



Carboniferous Limestone, p. 424. 



Coal Measures, p. 428. 



Organic Remains, p. 440. 



New Red Sandstone, p. 447. 



Rocks of Igneous Origin, p. 449. 



lanes of Disturbance, p. 452 



Diluvium, or Drift, p. 460 

 Conclusion, p. 463. 

 Appendixes, p. 475, et seq. 



A. Sections of Coal Pits, p. 475. 



B. Minerals of the Coal Measures, 



p. 487. 



C. Systematic list of Fossils, p. 488. 



D. Tabular list of Faults, p. 494. 



Illustrations.— PI. XXXV. to XLI. 



Introduction. 



J-N the following pages two memoirs are embodied. One of them, read be- 

 fore the Society in February 1834_, gave a short account of some of the prin- 

 cipal faults and disturbances of the Coalbrook Dale coal-field ; the other, read 

 April 1836, described the several formations comprised in that district, as well 

 as certain phasnomena exhibited by the coal-measures, and not noticed in the 

 former communication. 



Before I proceed, it is necessary to observe, that prior to the researches of 

 Mr. Murchison into the formations between the carboniferous rocks and the 

 slates of Wales, the examination of the Coalbrook Dale district was attended 

 with very considerable difficulties. A few of the rocks, which crop out 



3 H 2 



