394 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mav 26, 



hibited by the Upper Bagshot sands ; — else we may consider that the 

 upper and less fossiliferous Bracklesham sands (Nos. 14 & 15, sec- 

 tion 6) expand as they range northward and constitute the Upper 

 Bagshot sands ; — or again, that the Barton clays thin out, and that 

 the upper sands (Nos. 14 to 15) of the Bracklesham beds then come 

 into juxtaposition with the sands (No. 20) overlying the Barton clays, 

 viz. the Headon Hill sands (see PI. XIV. Comp. Sec. fig. 2); — further, 

 the Upper Bagshot sands may be the equivalents of the Headon Hill 

 sands, the Barton clays thinning out ; — or lastly, they may prove to 

 represent the whole of the upper division of the great arenaceous 

 series of Hampshire included between the Bracklesham Bay beds and 

 the Freshwater series. 



The solution of this problem requires however a more detailed ex- 

 amination than I have had time to make of the Barton clays, both at 

 Barton and in their range northward and eastward, and also of all the 

 beds between the Bracklesham sands and the Freshwater series. My 

 ovm opinion is rather in favour of the last of the views I have ex- 

 pressed above ; still I should be glad of farther and more conclusive 

 evidence. 



I have not been able to discover anywhere on the Bagshot sands 

 any traces or indications of overlying freshwater strata. 



Comparison of the Bagshot and the Alum Bay series. 



Having taken the White-Cliff Bay section as a type, we will now 

 proceed to examine how far the structural variations exhibited at 

 Alum Bay agree with the parallelisms sought to be established. The 

 great difference of conditions that prevailed during this geological pe- 

 riod at these two localities has produced results, which, had we not 

 good geological horizons both above and below this great arenaceous 

 series, it would be difficult to assimilate. 



In the first place, the rich and varied fauna existing at Brackle- 

 sham, and which already at "White-Cliff Bay shows a very material 

 decrease, has entirely disappeared at Alum Bay. A few unimportant 

 layers of lignite are the only connecting links in organic life between 

 the two sections. Nevertheless, if the central mass of variegated 

 sands and clays (Nos. 7 to 28) of Alum Bay is admitted to be syn- 

 chronous (for I think that the similar relative position in both sections 

 of the London clay, in their lower, and Freshwater series, in their 

 upper part, proves the synchronism of their intermediate strata) with 

 the central series, including the Bracklesham beds of White-Cliff Bay, 

 then it will follow, that this portion of the Alum Bay section is 

 synchronous with the Bagshot sands ; in confirmation of which hypo- 

 thesis the evidence, although restricted, is in perfect accordance (see 

 PI. XIV. Comp. Sec. figs. 2 & 3). 



The Alum Bay series affords but one term of comparison in or- 

 ganic remains with the Bagshot sands. Of animal life, as we have 

 before said, we have no traces, but remains of a rich and interesting 

 flora exist in great abundance and in excellent preservation in the thin 

 stratum No. 17. In a comparison with the strata at White-Cliff Bay 



