Yol. 56.] SHALES OF THE WELSH BORDERLAND. 387 



with associated igneous rocks, which Prof. Lap worth and Prof. Watts 

 refer to the lower part of the Bala ISeries. 1 These are uncon- 

 forraably overlain by Llandovery Beds, which are in turn succeeded 

 unconl'ormably by the Wenlock Shales. 



In the south, the Llandovery Beds rest on different members of 

 the Ordovician rocks. Near Betton they rest immediately upon the 

 Llandeilos (Middleton Group), but farther west the unconformity 

 is less clearly denned. The succession between the Llandovery and 

 Wenlock Beds appears quite conformable, though much is concealed 

 by alluvial deposits. 



Throughout the whole of the Long Mountain area the Wenlock 

 Shales pass up gradually into the Ludlow, and these in their 

 turn into the highest rocks seen, namely, the Old Red Sandstone, 

 which is exposed near the summit of the Long Mountain. 



Detailed Description of the Beds. 



Before describing in detail the sections in the Wenlock Shales 

 exposed at various points on the flanks of the Long Mountain, it is 

 necessary to say a little about the beds which underlie them in this 

 area. 



(i) Llandovery -Tarannon (?) Beds. 



Prof. Watts has already shown that beds of Upper Llandovery 

 age are exposed on the flanks of Middletown Hill near Buttington 

 Railway -station. They are also present in the southern part of 

 the district, near Betton, and in Hailsf'ord Brook. Apart from the 

 palaeontological evidence, the unconformity of these beds to the older 

 rocks is hard to detect in the north, but it is very marked at 

 some localities in the south, and can be very clearly seen along a 

 cart-track near Betton, which leads up to an old quarry excavated 

 in the Llandeilo rocks (Middleton Group). 



In all these localities the Llandovery commences with a well- 

 marked grit-band, which is invariably succeeded by a belt of fine 

 shales, purple in the north, though with paler bands in the southern 

 part of the district. These shales are unfossiliferous, but Prof. Watts 

 suggests that they should be referred to the Tarannon Shales, and 

 with this view I am in agreement. They are unlike any Wenlock 

 beds known to me, and north-east of Betton, near The Stubbs, they 

 are succeeded by strata which very closely resemble the base of the 

 W T enlocks, though I was not successful in finding fossils in them, 

 and therefore am unable to say definitely that they are of Wenlock 

 age. 



(ii) The Wenlock Shales. 



In describing the Wenlock Shales of the Long Mountain area, I pro- 

 pose to deal with continuous sections exposed along streams or roads, 

 and for this purpose shall group my sections under three heads : — 



(A) Sections on the North Side ; 



(B) Sections on the West Side ; 



(C) Sections on the South Side. 



1 Proc. Geol. Assoc, vol. xiv (1894) p. 320. 



