226 THE GEOLOGICAL STRUCTUEE OF THE 



and so meagre that we have not attempted to map them 

 separately, and therefore the beds of Bajocian age are, as 

 a matter of fact, marked Aalenian ; but their outcrop area 

 is so small that this is not a matter of importance. 



Besides the Survey Map there has been a map of Dundry 

 published by William Sanders. From what was said by 

 Mr. H. B. Woodward, F.R.S., at the discussion of our 

 paper,^ we gather that the Survey map was executed in 

 1845, and that therefore, so far as Dundry is concerned, it 

 is an earlier document than Sanders' map. That however 

 was not known to us ; we could only accept the statement 

 on the map itself, " geological information . . . revised 

 1867-1871." As Sanders' map was published some years 

 before the earlier of these dates — and it differed seriously 

 from the Survey Map, we supposed that the officers of the 

 Survey had ascertained which map was the more correct. 



Mr. H. B. Woodward further says that the differences 

 between our map and the Survey document are small. We 

 thought otherwise — in such cases as hundreds of yards. 

 But the following comparison mhII show how we differ both 

 from the Survey and from Sanders. 



(1) Comparison of the Geological Survey Map ^ with the 07ie 



here presented. 



The Geological Survey map represents at Dundry only 

 Inferior Oolite resting upon Lower Lias. The boundary- 

 line which we shall have to notice is that drawn separating 

 the deposits so classed. Beginning at the main road on the 

 north flank of the hill, and going westward, the Survey's 



^ Quarterly Journal Geological Soc, vol. 52, p. 720. 



2 Sheet XIX. ' Geological Information revised, and Penarth Beds sur- 

 veyed, by H. W. Bristow, H. B. Woodward, W. A. E. Ussher, and J. H. 

 Blake, 1867-1871. New edition. Published May, 1873.' 



