Revieivs — Geological Survey Memoirs. 273 



notes made recently. The Devonian rocks from the Hangman Grits 

 to the Pilton Beds are described, and the author remarks that "it is 

 unsafe to regard the Morte Slates as anything older than the upper 

 part of the Ilfracomhe Group or the beds immediately overlying it." 



Dr. Plett contributes a description of the Hestercombe ' syenite ' 

 which was discovered in 1814 by Leonard Horner, the rock being 

 now described as a diorite. 



The Carboniferous Limestone of Cannington is referred to the 

 Seminula zone. 



The author discusses the relations of the Carboniferous and Devonian, 

 observing that while there is no evidence of unconformity between the 

 Lower and Middle Culm Measures, yet "the existence of a consider- 

 able unconformity in South Devon and Cornwall leads one to think 

 that the appearances of concordance are not to be trusted." The 

 author is here rather more confident of the unconformity than he was 

 in the Plymouth memoir (p. 103), wherein he did not deny the 

 possibility that thrust-faults might explain the phenomena. 



In the Quantock area, as in that of Plymouth, there is no proof of 

 unconformity between Upper Devonian and Lower Culm Measures, 

 but the junction " is often faulted and generally obscure." 



The cherty beds of Coddon Hill have been regarded as homotaxial 

 with those of Bishopston in Gower, and as equivalent to the so-called 

 " Yoredale Beds," or to the Pendleside Beds of Dr. Wheelton Hind. 

 Mr. Ussher is, however, inclined to regard the Devon-Carboniferous 

 chert-beds as on a lower horizon than those of South Wales, and he 

 adopts the view put forth by Dr. G. J. Hinde and Mr. Howard Fox 

 that the Devon beds represent the deeper-water conditions of the 

 Carboniferous Limestone. The proof of deeper-water conditions is, 

 however, a moot point. 



Dealing generally with the effects of great earth - movements, 

 Mr. TJssher argues that "if the Devon Lower Culm-measures corre- 

 spond to the Carboniferous rocks above the Carboniferous Limestone, 

 and the Upper Devonian in no part represents the latter, the south 

 shore of a strait in the Carboniferous Limestone sea would have been 

 not far south of Cannington Park ; and south of this the Carboniferous 

 Limestone would not be found." He, however, adds, " The eqviivalence 

 of the Lower Culm Chert Beds to Carboniferous Limestone, owing to 

 a more or less uniform deepening of the sea-bed to the south and 

 south-west of Cannington Park, is here advocated." 



Full particulars are given of the JSTew Red rocks, including (1) the 

 Lower Sandstones and Marls, grouped as Permian, and (2) the Pebble 

 Beds and Conglomerate, the Upper Sandstones and Upper (Keuper) 

 Marls, grouped with the Trias. Mr. H. H. Thomas contributes 

 petrographical notes on the IN'ew Red sands and sandstones. Short 

 descriptions are given of the Rhtetic beds and Lower Lias which are 

 exposed along a small portion of the coast which comes in the area of 

 the map, near St. Audrie's, east of AYatchet. The work concludes 

 with some account of the Pleistocene and Recent deposits, and of 

 water supply and economic products, including the famous Bath 

 bricks of Bridgwater. 



DECADE V. VOL. V. — NO. VI. 18 



