Inferior Oolite in Gloucestershire. 403 



lished, where the united thickness assigned to them is 38 feet ; 

 the whole of the formation beneath, with the exception of about 

 2- feet, or about 189 feet of rock, belongs to the second zoolo- 

 gical assemblage, which it is the especial object of this compa- 

 rison to elucidate. The Inferior Oolite has long been known to 

 geologists for the great profusion which it possesses both in spe- 

 cies and individuals of the two great tribes of Ammonites and 

 Belemuites ; some few of these pertain to the first or uppermost 

 of our assemblages, but the great mass of these tribes, together 

 with a large and characteristic series of other shells, are absent 

 in the neighbourhood of Cheltenham ; these constitute a third 

 and still lower zoological sei-ies, to examine which, in situ, we 

 must visit the escarpment of the Cotswolds, some miles to the 

 southward of Leckhampton, and from thence we shall find this 

 assemblage to be persistent in gradually increasing importance to 

 the neighbourhood of Bath, and to extend throughout the whole 

 course of the formation in Somerset and Dorset to the English 

 Channel. In the two last-mentioned counties the localities of 

 Dundry, Sherborne and Bridport have become celebrated for the 

 profusion of their fossils, and until very recently museums and 

 collections have been supplied almost exclusively from those 

 sources, and the fossils of this third and lov^'est assemblage have 

 been held to represent those of the Infei'ior Oolite generally. In 

 the middle portion of the Cotswolds, or from Stroud to Wootton- 

 under-Edge, the three subdivisions of the Inferior Oolite are ex- 

 hibited by the various sections ; but a little to the southward of 

 the latter place, the uppermost division and upper portion of the 

 middle division thin out and are lost ; at the same time the Ful- 

 ler^s earth above attains a much greater importance, its thickness, 

 together with that of the Inferior Oolite, amounting to a little 

 more than the aggregate thickness of the two formations about 

 Cheltenham. The following imaginary section from Cheltenham 

 to Bath will make the subject more clearly understood. Thus 

 the Fuller's earth 148 feet thick at Bath has diminished to 70 feet 

 at Stroud, and in the vicinity of Cheltenham to a very inconsi- 

 derable band of clay. The lower division of the Inferior Oolite 

 (No. 4 in the section), consisting of several Ammonitiferous beds 

 with brown sands beneath, altogether 70 feet thick, has dimi- 

 nished to 40 feet at Stroud, and at Leckhampton is represented 

 by the lowest bed 2 feet thick, charged in the usual characteristic 

 manner with Belemnites, beneath which are 6 inches of chocolate - 

 coloured sands reposing upon the blue marls of the Lias. The 

 upper division or Ragstones (No. 2 in the section) about 40 feet 

 thick near Cheltenham is reduced to 20 at Stroud, and is ulti- 

 mately lost to the south of Wootton as before mentioned. 



The middle division, nearly 190 feet thick at Leckhampton, is 



27* 



