772 Geological Society. 



possible between the graptolitic zones of the Gyffin Shales and 

 corresponding beds at Rhayader, Tarannon, in the Lake District, 

 and the South of Scotland. Finally, the Benarth Mags are com- 

 pared with the Brathay Flags, the Riccarton Beds, and beds above 

 and including Gyrtograptus murchisoni in the Tarannon district. 



2. ' The Depth and Succession of the Bovey Deposits.' By 

 Alfred John Jukes-Browne, B.A., F.G.S. 



The total thickness of the Tertiary Beds in the Bovey Basin has 

 never yet been ascertained, because no boring has yet reached the 

 bottom of the basin in which they lie ; and no one has yet 

 attempted to make out a stratigraphical succession from the 

 sections exposed in the numerous clay-pits. 



Some years ago, however, Messrs. Candy & Co., of the Heathfield 

 Potteries, put down a boring which reached a depth of 526 feet 

 from the surface. Having obtained some particulars concerning the 

 beds traversed by this boring, the author is able to discuss the 

 succession of the Bovey deposits, so far as they have been explored. 

 The following is a generalized description of the strata seen in the 

 Heathfield pit, and penetrated by the boring from the bottom of 

 that excavation : — 



Thickness in feet. 



Superficial deposits about 20 



Beds of clay and sand, with occasional beds of lignite ...... 250 



Beds of lignite and clay, with one of sand 36 



Beds of lignite, with thin layers of clay 220| 



526 



The author confirms the conclusion arrived at by Pengelly in 

 1861, with regard to the relative age of the beds exposed in the 

 ' old coal-pit ' south-east of Bovey Tracey and those proved in 

 a boring to the east of it. From all the data mentioned, and 

 assuming the actual base of the Tertiary deposits to be not more 

 than 30 feet below the bottom of the Heathfield boring, he estimates 

 the total thickness of the ' Eocene ' beds to be about 613 feet. 



The Bovey Basin itself is regarded as a tectonic basin or post- 

 Eocene pericline, and not as a lake-basin ; although, during the 

 deposition of the higher part of the series, it may have formed part 

 of a large lacustrine or lagoon area, extending over the greater 

 part of East Devon. 



The author dissents from Heer's view of the manner in which 

 the lignites were formed, discusses the identification of some of the 

 plants, and concludes that the lignites which form the mass of the 

 lower beds represent the growth and decay of successive swamp- 

 forests, similar to that of the Great Dismal Swamp of Virginia at 

 the present day. 



Assuming that these lower beds are of Eocene age, and con- 

 temporaneous with the Bournemouth Beds of the Hampshire Basin, 

 the author points out that nothing has yet been proved with regard 

 to the higher beds, which may be of Bartonian, or even of Oligocene 

 age. 



