176 PEOF. J. W. JUDD ON THE OLIGOCENE 



between the Colwell-Bay marine band and the shore at Totland Bay. Hence 

 Forbes was fully justified, taking his interpretation of the section, in placing 

 the Headon-Hill sands where he did ; and the fact of their absence at this 

 point is clear proof that he was mistaken in his interpretation. 



In fig. 2 the vertical and horizontal scales are different, but the relations 

 between the several heights, as fixed by the new Ordnance Survey maps, are care- 

 fully maintained. Now the position of the Bembridge Limestone on Headon Hill 

 is found to be 250 feet above the sea- level, at the point where the brackish- water 

 strata of Headon Hill crop out on the shore. The vertical sections of the 

 Greological Survey give the distance between the Bembridge Limestone and the 

 Headon-Hill brackish-water bed as 125 feet. The discrepancy is so great that 

 it is impossible to account for it by supposing a sudden thickecing and change 

 in character of the whole of the beds. But the new interpretation, illustrated 

 by the dotted lines in this figure, removes all difficulties, and the strata of 

 Headon Hill are brought into exact correlation with those of Totland Bay. 

 Unfortunately that part of the section in which the Brockenhurst series would 

 be found is entirely concealed by a talus from the beds above and the gravel 

 which caps the hilL 



In fig. 3 the same section is drawn upon the same vertical and horizontal 

 scale, so that the exact relations of the several beds are clearly shown. 



Discussion. 



The Peesident, in proposing a vote of thanks, expressed his sense 

 of the value of Prof. Judd's communication. 



Prof. Peestwich said that, notwithstanding the ability displayed 

 in the paper, he was not yet prepared to accept all the conclusions, 

 more especially as regards the correlation of the Headon-Hill beds. 

 It was his impression that the Headon-Hill sands just reappeared in 

 Totland Bay, and that the variation noticed by Prof. Judd in the 

 marine beds at Headon Hill and ColweU Bay might be due to the 

 more freshwater conditions which prevailed at the former place. 

 He doubted also if the beds at Brockenhurst quite bore out Prof. 

 Judd's opinion. It must be remembered that these beds varied 

 much in thickness and in character. As to the importance of the 

 Oligocene formation, he quite agreed with the author. 



Prof. Duncan referred to the contests on the subject of the term 

 Oligocene in the year 1863. He had studied the classification of 

 these beds from the point of view of their coral fauna. Th^t 

 showed the existence of a formation intermediate between Eocene 

 and Miocene. Beds in Scinde bore similar testimony to those of 

 Europe.. This was represented in Britain by the Brockenhurst 

 fauna, which he had considered the equivalent of the " Tongrien 

 Inferieur." He welcomed therefore Prof. Judd's classification and 

 acceptance of the Oligocene. 



Mr. Etheeidge said Yon Konen had identified the Oligocene in 

 England in 1863. He thought Prof. Judd had gone far to clear up 

 the difficulty which every student must have felt about the Colwell- 

 Bay beds. After reading the details given by Prof. Judd in his 

 paper, it might be possible to form an opinion as to the reason of 

 the remarkable oscillations shown in the south of England and in 

 Germany by this series. To clear up some of these difficulties 

 would be a great boon to the Tertiary geologist. 



Prof. Seeley thought that Yon Konen had identified the Colwell- 

 Bay bed with the Brockenhurst [Prof. Judd explained it was so ; 

 but he had identified them with the Headon-Hill beds also]. There 



