Vol. 59.] THE TOAKCTAN OF BREDON HILL. 451 



The appended diagram (Table IV) probably represents the rela- 

 tions of the Toarcian to the Aalenian strata, from Bredon Hill to 

 Standish Beacon — interpreting the evidence of a non-sequence in 

 the Cheltenham district as indicating an anticline in the neigh- 

 bourhood, and suggesting that such anticline probably coincides 

 with the Birdlip axis, noted in connection with similar anticlines 

 in Bajocian and Aalenian strata. 1 The diagram also shows the vary- 

 ing lithic facies of the strata in question ; and that the lithological 

 planes run somewhat obliquely in regard to the palaeontological 

 horizons. Somewhere in the Birdlip neighbourhood the Aalenian 

 Sands may be expected to rest directly upon the Toarcian or 

 Cotteswold Sands — a curious result, which would give an apparently- 

 lateral continuity of sandy deposits, when it is really superposition 

 and a non-sequence. 



III. Comparison of the Cotteswolds and Dorset. 



While upon the subject of the development of sands, it may be 

 useful to compare certain Toarcian (and some Aalenian) strata of 

 the Dorset coast with those of the Cotteswolds. The Bridport 

 Sands of the Dorset coast are much later in date than the Cottes- 

 wold Sands ; they did not begin to be deposited until some time 

 after the Cotteswold Sands had ceased — they are, in fact, four hemerse 

 later. 



I took the opportunity, some years ago, of measuring them with the 

 level, in the same way as I had done the Cotteswold Sands ; and also, 

 where possible, I measured them with the foot-rule up road-cuttings, 

 examining the different layers of nodules. They yield sometimes a 

 very fine series of ammonites, but a fauna quite distinct from that 

 of the Cotteswold Sands. The sequence which they show is of 

 particular interest: the manner in which the strata with the 

 aalensis-type of ammonite follow those with fine-ribbed Dumor- 

 tierice of the Jloom-type is especially noticeable. This can be 

 appreciated in the thick deposits of the Dorset coast, whereas in 

 the thin strata of the Cotteswold Cephalopod-Bed the sequence is 

 difficult to recognize. 



Table V (p. 452) embodies a comparison of the Cotteswold and 

 Dorset strata, with some remarks. 



It may be noticed that the periods of maximum and minimum 

 deposits just interchange in the two areas. During the hemerEe 

 falciferi to variabilis, thick deposits of clay and sands were being 

 laid down on the Cotteswolds, but thin deposits of limestone in the 

 Dorset coast-area. During and after the time of Dumortierice, 

 however, the state of affairs is just the reverse, thin limestones 

 prevailing in the Cotteswolds, thick sands and clays in Dorset. 



This is a matter of some biological importance. Morris & Lycett, 

 looking at the Cotteswold Cephalopod-Bed, considered that the 



1 ' BajociaD, &c. in the North Cotteswolds ' Quart. Journ. G-eol. Soc. vol. lvii 

 (1901) pi. vi. 



