^82 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 18, 



fig. 2), and are then succeeded by three tiers of a fine-grained mi- 

 caceous stone containing more or less lime (c). This is the first 

 appearance of mica in the Middle Lias ; and from this horizon up- 

 wards it will be found to occur at intervals up to the highest of the 

 Upper Lias Sands. The thickness of the blocks in the " Three Tiers," 

 as I have termed them, varies much, as does likewise that of the 

 intervening marl ; in the aggregate they measure from 20 to 26 feet. 

 Above these, in Westhay Cliff, we find some 20 feet more of micaceous 

 marl (6), which is succeeded by Greensand (a). There is thus a 

 thickness of about 220 feet of Middle Lias in this hiU ; and the best 

 exposure of the beds is to be seen upon Westhay Cliff at, and to the 

 eastward of, a gully called " Breakneck." Prom this point to the 

 eastward the cliff decreases in height, and the beds dip in the same 

 direction, as far as a little stream called Ridge Water, near which 

 a piece of broken swampy ground conceals a downthrow to the east, 

 of about 40 feet. This brings us to Gabriel's Water, at which com- 

 mences the fine section of the Golden Cap. 



Fig. 2.— Vertical Section of the Middle Lias at Westhay Cliff. 



feet. 



a. Greensand, chert, and Drift .... about 180 



b. Grey micaceous marl 16 to 20 



c. "The Three Tiers" — micaceous sandstone in 

 sandy micaceous shale and grey marl — about 20 



d. Grey marl (not micaceous) with thin ferru- 

 ginous seams, and masses of pyrites ... 73 



e. The Green Ammonite-beds — nodules imbed- 



ded in grey marls 18 



/. Grey marl, as above 15 



g. The Belemnite-stone. 



h. Grey shale and layers of marl. 



ft. Grey marl 16 to 22 



k. Grey Lias stone 12 to 18 



/. Blue marl 32 



m. Limestone with Belemnites ; Ammonites rari- 

 costatus in the lower beds. 



n. Lower Lias 30 to 40 



3. The Golden Cap. — The principal portion of this hill is based 

 upon the Belemnite-beds (*, fig. 3), and the marls immediately over 

 the beach are those containing the Green Ammonite-nodules. Above 

 these, the « Three Tiers" are here finely developed, and form a remark- 



