252 A. J. Jukes- Brow ne-r-T he Purbeck Beds 



III. —The Purbeck Beds of the Vale of Wakdour. 

 By A. J. Jukes-Browne, B.A., F.G.S. 



rriHE paper written by the Eev. W. E. Andrews and myself, pub- 

 X lished in 1894, gave a more complete account of these beds than 

 had previously been attempted ; we showed that they were divisible 

 into Lower, Middle, and Upper groups, comparable with those 

 established by Professor E. Forbes in the Purbecks of Dorset, and 

 characterized by the same species of Cyprides. This paper was based 

 on the joint examination of exposures visible in 1890, though one 

 of us, being then resident at Teffont, had observed and collected from 

 these exposures for many years. 



In the following year (1895) Mr. H. B. Woodward's memoir on 

 the " Middle and Upper Oolitic Rocks " was published, and his 

 account differed from ours in several particulars, notably as regards 

 the thickness of beds referable to the three several divisions, as to 

 the interpretation of the section near Dinton Station, and as to the 

 total thickness of the formation. We refrained from comment at 

 the time, partly because we were prepared to accept such corrections 

 as were based on the freshly cut exposure near Dinton, and partly 

 because the mapping of the district had not then been completed, and 

 we were content to wait till this was done, in the expectation that 

 Mr. Woodward would then reconsider some of the points on which 

 we were not in agreement with him. 



The mapping of the area was completed in 1900 by Mr. C. Eeid, 

 and this year (1903) the map (Sheet 298, new series), together 

 with an explanatory memoir prepared by Mr. Eeid, have been 

 published. I am sorry to find, however, that the account of the 

 Purbeck Beds in this explanation is merely a reprint of that given 

 by Mr. Woodward in 1895, without any alteration, and with only 

 some small additions by Mr. Eeid. As the Geological Survey has 

 failed to take advantage of this opportunity for revision, and as 

 silence on our part might be understood as an admission that no 

 such revision was necessary, I think it desirable to discuss some 

 of the points in which our account differs from that given by 

 Mr. Woodward. On some of these .questions Mr. Andrews and 

 I are disposed to modify the opinions expressed in 1894, but on 

 others we continue to think that our views and observations are 

 correct. We regret that it has not been possible for all concerned 

 to meet on the ground, for we think that if this could have been 

 arranged we should have come to an agreement on most, if not on 

 all, the points of difference. 



1. The Section at Wochley. — Mr. Woodward's account of this 

 section is so different from ours that it is not easy to correlate the 

 one with the other ; but one point is clear, that he does not take the 

 same plane of division between the Portland and Purbeck Series 

 as we did. In this matter I am obliged to maintain that our 

 account of the succession is not only fuller but more accurate than 

 Mr. Woodward's, for he has not sufficiently distinguished between 



