Vol. 63.'] OF THE BATH-DOTTLTING DISTRICT. 399 



this deposit is of Truellii hemera along with the Upper Coral- Bed. 

 Fortunately, the Marston-Road section is not yet overgrown, as is 

 the case with so many of the exposures described by Moore. The 

 capping of the section is a bed of horizontal Inferior Oolite, 2 feet 

 thick, rather dense and conglomeratic at its base, hut containing 

 many organic remains of that age. 1 The occurrence of Pecten 

 (Syncyclonema) demissus, Phillips, Acanthothyris spinosa (Schloth.), 

 Terebratula (probably T. globata, auctt.), Tsocardia sp., Trigonia 

 sp. indet., and an Ostrea, together with the lithological structure, 

 point to a deposit of Garantiance hemera. This rests upon ' a very 

 dense unstratified deposit of Liassic age,' the precise date of which 

 has not been ascertained, although Moore believed it to be ' about 

 that of the passage of the Lower into the Middle Lias ' ; while below 

 it, and separating it from the Carboniferous Limestone, are Rhsetic 

 beds barely a foot thick. 



Although in most of the Whatley-Combe sections, and in those 

 in the immediate neighbourhood, the Doulting Beds rest directly 

 upon the Carboniferous Limestone, there are places — besides the 

 quarry north of the inn at Holwell and the Marston-Road section — 

 where they do not. That this is so is obvious from the valuable 

 researches of Charles Moore, who found, somewhere near Whatley, 

 a Liassic deposit only a few feet thick, extremely fossiliferous, 

 nevertheless, in the lower portion, parting the Inferior Oolite from 

 the Carboniferous Limestone. Such Liassic deposits as these are 

 not representative of the whole of the series, as developed, for 

 example, in the Cheltenham district, but only of parts. During 

 Liassic times, and particularly in the vicinity of the Mendip Hills, 

 pene-contemporaneous erosions of the Liassic beds were frequent. 

 Even in the thin deposit near Whatley there may be more than one 

 non-sequence. Certainly the passage from the Lias to the Inferior 

 Oolite is not sequential ; there is a considerable break between 

 them, due to the Bajocian denudation. In the section near Whatley 

 no noticeable unconformity apparently marked the junction of the 

 Inferior Oolite and the Liassic Series. In the quarry at the back 

 of the inn at Holwell, however, there is one of Moore's ' dykes,' in 

 which vertical infillings of Lias and Rhaetic are overlain by hori- 

 zontal Inferior Oolite. The history of this ' dyke ' seems to be 

 somewhat as follows : — .First a fissure in the Carboniferous Lime- 

 stone was infilled in Rhaetic times by a deposit consisting of a pale 

 greenish-yellow marl, with small quartz-pebbles and Rhaetic verte- 

 brate-remains. This fissure was widened about the marmoreal 

 hemera, as appears to be indicated by the occurrence of Ornithella 

 sarthacensis (d'Orb.) 2 in the rock flanking the Rhaetic deposit. 

 A still further opening occurred about the gmuendensis hemera, 

 judging by the introduction of rock and clay (some of which 

 Mr. Upton washed, without, however, finding any micro-organisms) 

 containing S/ririferina Walcotti. On the top of this ' dyke,' and 



1 C. Moore, Quart. Journ. Geol. Soc. vol. xxiii (1867) p. 482. 



2 = Terebratula perforata, auctt. (teste S. S. Buckman). 

 Q. J. G. S. ISTo. 252. ' 2 g 



