EOCES OF SOMEESET AND DEVON. 373 



rapid to the south than to the north of the Mendip hills, and certainly 

 could never have heen so unequal as to cause the sediments formed 

 in the northern area to bear so small a proportion to those thrown 

 down in the southern districts, on the assumption that deposition 

 took place contemporaneously in both, we have every ground for 

 inferring with Sir H. De la Beche that " deposits were not effected 

 over the northern area to any great extent until the period when 

 the red marls prevailed, when the waters of the time evidently 

 overspread a considerable portion, there being a free passage of sea 

 between Wales and Devon, with outstanding islands." 



II. Area of the Polden HiUs, B ride/ ew ate r and Taunton Vale. 

 (a) Bridgewater District. 



We have placed this area second in order, not only because it 

 separates the northern from the southern area, but because it seems 

 to present a transition stage between the simple uniformity of the 

 Triassic deposits in the one, and their more complex and variable 

 nature in the other. 



We include in this district the country on the south of the 

 Quantocks as far west as Taunton. It is therefore bounded on the 

 south by the Liassic tableland (on the north-eastern side of the 

 Blackdown Range), on the cast by the Polden hills, and on the 

 north by the Otterhampton Liassic strata, the beds resting upon the 

 slopes of tho Quantocks upon their north-cast, east, and south flanks. 



The Trias in this area, east of a line drawn north and south 

 through Bridgewater, and south of a line drawn in an east and 

 west direction through Monkton Heathfield, appears to consist 

 entirely of red variegated marls of the same character as those on 

 the north ; that is, everywhere marls are at the surface ; but whether 

 they rest directly on the older rocks or conceal lower beds of dif- 

 ferent characters, we are, through the want of sufficiently deep 

 excavations, unable to say — though, from the presence of arenaceous 

 beds in places on the south slopes of the Quantocks, we are inclined 

 to believe that an intercalation at least of arenaceous matter with the 

 marl occurs near the base of the Vale-of -Taunton Trias, marking the 

 marginal accumulations of a coast receding with gradual subsidence. 



This view is in a measure borne out by the observations of Mr. 

 Moore, to whom we are again largely indebted. He gives a section at 

 Kuishton, north of Taunt on*, 21 feet 5 inches in depth, consisting of — 



ft, in. 



Red. bluish green, and grey marls 9 7 



Gritty conglomerate with occasional sandy bands and inter- 

 mediate layers of marl, with Fish, Eeptile, and Batrachian 

 remains (including teeth of Labyrinthodon, ? Belodon, 



Acrodus Jceujperinus, Esther iaminuta, &c.) 1 2 



Sandstone ' 2 



Fine sandy bed , 6 



Bluish and red marls « 10 



At Xorth Curry, under an undetermined thickness of variegated 

 marls, Mr. Moore notes the occurrence of various beds of dull grey 

 * Quart. Journ. Geol. Soc. vol. xxiii. p. 468. 



