England and the " Red Chalk " of the Eastern Counties. 161 



near Saiidown, the cliff-exposure of the Gaiilt is for the most part 

 rendered unfavourable for fossil-collecting by slipping of the clay 

 and by a thick naantle of turf. A few feet of the lowest beds, 

 immediately overlying the so-called " Carstone " of the Lower 

 Greeusand, were found to be exposed on the occasion of our 

 visit last year ; but the clay was much weathered and numerous 

 crushed casts of ammonites were the only fossils obtainable. These 

 are ribbed hoplitids, all in a state unfavourable for identification. 

 Their abundance suggests strongly that the interruptus-zone is here 

 present, and this is the accepted view of others who have studied 

 this section.^ It must be noted, however, that the mode of 

 preservation of these fossils differs from that so generally found to 

 hold good in the interruptus-Gau.lt of most other localities in this 

 country. 



Between Luccomb and Bonchurch the Gault is obscured by the 

 extensive debris of the great landslip, but phosphatic nodules con- 

 taining ammonites referred to the i7iterruptus-Gsiu\t have not 

 infrequently been found on the beach below. At Blackgang we have 

 failed to obtain access to any exposure of the Gault undoubtedly 

 in place ; but we have seen hoplitid ammonites of the interruptus- 

 zone found at this locality. 



At Compton Bay, near Freshwater, the characters of the lowest 

 part of the Gault are well contrasted with those of the lower beds 

 at Redcliff. The rock is of a more silty nature, and ammonites are 

 extremely rare. The few lamellibranchs found by us included Lima 

 {ManteUum) gaultina Woods, a species always common in the lowest 

 part of the transgressive Upper Gault of the Dorset coast. 

 Inoceramus sulcatus Parkinson has also been found in the lowest beds 

 of the Gault here, as recorded by M. W. Norman. If the identification 

 of this easily recognized species was correctly made, which there is 

 no reason to doubt, the record of " Ammonites dentatus " from this 

 locality must have referred to one of the Upper Gault hoplitids, so 

 easily confounded with the earlier forms. In the light of our 

 examination of the Gault along the coast of Dorset, we can only 

 conclude that at Compton Bay the Upper Gault has overlapped on 

 to the Lower Greensand. There is, indeed, doubt whether the so- 

 called " Carstone " of this locality represents the true top of the 

 Lower Greensand. 



Dorset and Devon. — In South Dorset the Gault can be studied at 

 Worbarrow Bay and at intervals westward as far as Holworth 

 House, near White Nothe. From the published accounts of the 

 section at Worbarrow Bay there is nothing to indicate the presence 

 of any Lower Gault there. At that locality there is a marked line 

 of erosion at the base and the Gault is in the condition of sandy 

 and silty clays, as is also the case at Mupe Bay, where much of the 

 section is obscured by talus. 



^ H. J. Osborne White, " A Short Account of the Geology of the Isle of 

 Wight" : Mem. Geol. Surv., 1921, p. 51. 



VOL. LIX. — NO IV. 11 



