56 



On a Section of the Lias and Recent Deposits in the Valley of the 

 River Frome, at Stroud. By E. W. Witchell, F.G.S. 



Read at Toktworth, August 19th, 1865. 



Section. 



ft. in. 



a Surface mould, passing into buff-coloured clay or brick-earth. Varies ) „ . 



from 2 to 5 feet thick j-iu 



6 Peat, formed of leaves, rootii, water-planta, and river mud. Contains } „ q 

 shells of nuts, &c ) 



c Gravel, resting upon Lias Marl ^d.J The surface of this Marl is undu- f »„ 

 lating, so that the thickness of the Gravel varies considerably . • ( r 



d Blue Lias Marl, in which are three layers of brown concretionary (go 

 nodules, about 3 feet apart, composed chiefly of casts of fossils . . j 



c Lias Shale and Limestone, irregularly bedded, and of variable degrees'! 



of hardness, containing layers of shells in the partings ; the whole > i 

 very fossiliferous ) 



/ Lias Shale 2 0. 



g Oyster bed, composed of valves of G. Cymbium 2 



h Lias Shale. Plesiosaurus remains at a depth of 3 feet. 



There is now in progress on the bank of the river Frome, 

 about half-a-mile below the town of Stroud, an excavation in 

 the river gravel, and in the more recent drift and overlying clay, 

 which is of considerable interest. The excavation, which is 

 circular, is 136 feet in diameter, and nearly 30 feet in depth, of 

 which about one-third is in the recent deposits, and the 

 remainder is in the upper beds of the Lower Lias. 



A section from an excavation in an adjoining meadow is given 

 in the Transactions of the year 1860, but, as that excavation 

 was comparatively small in extent, the opportunity for observa- 

 tion was less favourable than in the present case. I have there- 

 fore made a more complete section of the beds. It may also 

 be mentioned that the beds d. e.f, and which are referred to 

 in the former section as blue Marlstone, are in the zone of 

 Ammonites Henleyi, the young forms of A. macwlatus (A capri- 

 comus SchlothjJ being abundant. A few aged examples of the 

 same species, which there is reason to suppose are identical with 

 A. Henleyi, Sow., were likewise obtained. 



