Vol. 6^.~] OF THE BATH-DOTTLTING DISTRICT. 385 



glomerate-Bed.' Still farther south it is overstepped by the 

 Doulting Stone, which at Hapsford Mills, near Elm, rests directly 

 upon the Khsetic White Lias, the top-bed of which is conspicuously 

 bored ; and in Yallis Yale, upon the well-planed, bored,-and oyster- 

 covered surface of the highly-inclined Carboniferous-Limestone 

 strata. In the valley between Egford Bridge and Broad Grove, 

 Cloford, the Oolite rests in most places upon the Carboniferous 

 Limestone, but sometimes — as the researches of that indefatigable 

 geologist, Charles Moore, demonstrated — upon a thin deposit (only a 

 few feet thick) representing a portion or the whole of the sediment 

 laid down during the Rhsetic and Liassic Periods at those particular 

 places. 



On the south side of the Mendip Hills, in the railway-cutting at 

 Doulting, a conglomerate-bed with Terebratula sphceroidalis (about 

 16 inches thick) represents the Upper Trigonia-Grit, and rests 

 upon bluish, micaceous, shaly clays. 



The relationship of the Upper Trigonia-Grit to the underlying beds 

 is interesting. In the well-known section at Leckhampton Hill, 

 Cheltenham, the ' grit ' is separated from the Upper Liassic de- 

 posits by beds measuring about 194 feet. In the neighbourhood of 

 Wotton-under-Edge the thickness of the intervening beds is about 

 48 feet ; but at Midford there are no intervening beds — the Upper 

 Trigonia-Grit rests directly upon the Midford Sands. In other 

 words, when traced from north to south, the Upper Trigonia-Grit 

 is seen to transgress the outcrop-edges of successively-older beds, 

 and is itself overstepped in the immediate vicinity of the Mendip 

 Hills by the Doulting Stone. 



Usually, where the Upper Trigonia-Grit is present in the Bath- 

 Doulting district, it rests directly upon the Lias. 



Generally speaking, immediately below the Upper Trigonia-Grit 

 in that part of the district to the north of a line drawn east and 

 west through Carnicote, 1 near Timsbury, are the Midford Sands, 

 which decrease in thickness from north to south. Along a narrow 

 strip of country between this line and another drawn parallel to it 

 about half a mile farther south, the -grit ' and the local Cephalopod- 

 Bed — which occurs, not above the Sands as it does in the neigh- 

 bourhood of Wotton-under-Edge, but below — are in apposition. 



South of the last-named east-and-west line it would appear 

 reasonable to suppose that the Upper Trigonia-Grit rests upon 

 whatever Middle and Lower Liassic deposits are present. In the 

 railway-cutting near Mells-Boad Station it reposes on blue shaly 

 clays, from which water is thrown off. 



A short distance farther south the Upper Trigonia-Grit dies out, 

 being overlapped by the higher beds, which, judging from the 

 Geological- Survey map, pass on to the littoral Keuper and 

 Palaeozoic rocks in the neighbourhood of Mells village. Seeing, 

 however, how many local erosions occurred during the time of 

 formation of the Lias of the Radstock area, it is more than likely 



1 Called ' Carlingcott ' on the new Ordnance-Survey map. 



2f2 



