100 



H. KEEPING AND E. B. TAWNEY ON THE BEDS AT 



the excavations at the new Beading Booms is supposed to prove 

 " that beds are [there] found which have their exact counterpart in 

 the Headon-Hill section, not at the base, but at a much higher part 

 of the series." "We can readily understand that the Upper Bagshot 

 sands were not found in the excavation; we could even have 

 predicted the fact beforehand ; from a rough calculation, we estimate 

 that the sands are above a dozen feet below the foundation. In 

 favour of this view, we may add that, when the old wooden pier was 

 being made, one of us heard from those engaged in the work, that 

 the piles were driven with difficulty because of their piercing solid 

 sand *. 



But putting aside the question as to their exact depth here below 

 the Beading Booms, we are able to refute the notion that any thing 

 higher than Lower Headon beds exist here. As mentioned above, we 

 recognized immediately behind the Beading Booms the live Lymnaea- 

 limestones which come below the Potamomya-sand, both at Widdick 

 Chine on the south, and Weston Chine on the north, between which 

 places the sands may be traced almost continuously. The whole of the 

 cliffs between Weston and W T iddick Chines are occupied solely and 

 throughout by Lower Headon beds (neglecting the cap of Post- 

 tertiaries). All this part of the section (op. cit. pi. vii. f. 2) is in- 

 accurate, in consequence of the Middle Headon being placed too low 

 in Headon Hill. 



Middle Headon of Warden Cliff. — Again, we cannot agree with 

 that part of the section between Weston Chine and Warden Point. 

 Here no marine bed is indicated ; for in fig. 3, the section drawn to 

 true scale, the Colwell bed is made to die out before the Warden 

 battery is reached, which is occupied by an exaggerated thickness of 

 gravel f . 



There is no fact more patent to any observer than that the Col- 

 well-Bay marine bed extends all through Warden Point and Cliff, 

 where it is supported by the How-Ledge limestone. We made a 

 measure in detail of the Colwell marine bed (Middle Headon) at a 

 point about midway between Warden Battery and Weston Chine ; it 

 is here 34^- feet thick ; we noticed there the Neritina-bed } with its 

 characteristic features and fossils below the Venus-bed as at Col- 

 well Bay and Headon Hill. It would be wearisome to give all the 

 details ; but the Colwell bed here is easily recognizable as identical 

 with the Middle Headon of Headon Hill, both physically and pahe- 

 ontologically. At Warden Battery, above the Middle Headon, comes 

 some Upper Headon § besides the Post-tertiary cap. 



In the section drawn to true scale (pi. vii. fig. 3) the Colwell- 

 Bay marine bed has its horizontal extension curtailed by almost one 



* The iron columns of the new pier are stated to pierce a bluish clay ; we 

 should interpret this to indicate the clays immediately above the Upper Bagshot 

 Sands, and which are described as greenish in the Survey section. 



t We cannot reconcile this with fig. 2 of the same plate, where the marine 

 bed is more nearly correctly drawn. 



\ Previously noted as bed 16 by Dr. Wright, Proc. Cotsw. Club, i. p. 95, and 

 Ann. & Mag. Nat. Hist. s. 2, vol. vii. 



§ Described by Dr. Wright in 1850 as bed 5, Proc. Cotsw. Club, i. p. 90. 



