354 MR. RICHARDSON ON NON-SEQUENCE BETWEEN [Aug. I9O4, 



now exposed in the sections at Aust and Westbury ' must have 

 been deposited in a different area, and open to another sea or 

 estuary.' 1 



In the foregoing record of certain stratigraphical details, frequent 

 reference has been made to th e Bone-Bed or Bon e-Bed-equi- 

 valent. That term has been employed for the want of a better. 

 By the use of this denomination I do not imply that the stratum is 

 necessarily crowded with vertebrate-remains : it happens to be so at 

 Garden and Wainlode Cliffs and Coomb Hill in the district under 

 review ; hence the reason why it has been made use of to indicate 

 the equivalent deposit in other localities, even if that equivalent 

 does not contain vertebrate-remains. I am inclined to think that 

 this Bone-Bed (15) w^as accumulated slowly. At Aust and Sedbury 

 Cliffs it is conglomeratic, and might at first sight appear to have 

 been formed somewhat rapidly, but the deposit at these localities 

 is a littoral accumulation. In the Black Shales which were laid 

 down during the contorta-age, fish-remains as a rule are not 

 abundant ; and I am inclined to agree with Strickland's idea that 



'this great continuity of extent [of the Bone-Bed], combined with the pro- 

 digious abundance of organic remains in some parts of this stratum, render it 

 probable that a much longer period may have elapsed during its deposit than 

 in the case of an equal thickness of the less fossiliferous clay-beds above and 



below Generations of fishes and saurians may have added their remains 



to the common mass, while from the clearness of the water, or from the 

 existence of a gentle current which prevented the deposit of muddy particles, 

 scarcely any mineral matter was added to the bottom of the sea.' 2 



Now, as a rule, the fish-remains in the Bone-Bed at Wainlode Cliff 

 occur in regular layers, and are very evenly distributed : the rock 

 being fissile, and in all respects resembling a deposit which was 

 formed slowly. But the bed, which is about an inch thick at one 

 end of Wainlode Cliff, took the same time in its formation as the 

 30 inches of sandstone at Dunhampstead. 



Accumulations of vertebrate-remains or ' Bone-Beds ' occur at 

 different horizons in the Lower Rhoetic Stage ; for example, the 

 ' Bone-Bed ' at Crowle, near Worcester, is Bed 13 ; at Wainlode 

 Cliff and Coomb Hill, Bed 15 ; at Denny Hill, Bed 13 ; while at 

 Garden Cliff there are at least four deserving of the name. More- 

 over, the Pecten-Beds (7 & 5 b) are often full of vertebrate-remains, 

 so much so that the bed distinguished in my record as 5 b at 

 Wainlode Cliff was noticed by Strickland as ' a second ossiferous 

 bed.' The stratum which has been distinguished as 15 in com- 

 munications made to the Cotteswold Naturalists' Field-Club, and 

 that dealing with Sedbury Cliff to this Society, may at first sight 

 appear to occupy different horizons, but this is only if the several 

 sections be studied from the base upward. 



There is always some difficulty in correlating the various sections, 

 because of the want of fossils known from investigations over large 



1 Trans. Cardiff Nat. Soc. vol. iii (1870-71) pt. ii, p. 47. 



2 'Memoirs of H. E. Strickland ' 1858, pp. 157, 158. 



