716 MESSES. S. S. BTJCKMAN AND E. WILSON [Nov. 1896, 



As a matter of fact, so far as Dundry is concerned, the line which 

 we draw to mark the commencement of deposition in Aalenian 

 time should coincide with the line which the officers of the Geological 

 Survey have drawn as the base of the Inferior Oolite. That there 

 is not always such coincidence is due to the error about the 

 Marlstone already alluded to (pp. 683, 706). Then the area enclosed 

 by our Bathonian-Aalenian lines represents what would be called 

 ' Inferior Oolite, g 5/ so far as Dundry Hill is concerned ; and the 

 limits that we have laid down may be regarded as = ' Inferior 

 Oolite ' planned to the best of our ability. 



As to what our terms ' Aalenian,' etc., represent, the reader is 

 referred to Table IV., facing p. 696. Of course, only the commence- 

 ment of the Bathonian age is now represented by deposits at 

 Dundry. The deposits of Bajocian age there are so incomplete and 

 so meagre that we have not attempted to map them separately, and 

 therefore the Bajocian beds are, as a matter of fact, marked 

 Aalenian ; but their outcrop-area is so small that this is not a 

 matter of importance. 



Our method of procedure in regard to the mapping was as 

 follows : — We paid two or three visits to the hill in company, and 

 decided the limits of our divisions at certain of the more important 

 points. The mapping, of the intermediate country was done by one 

 of us (E. Wilson) alone, tracing the deposits of the different hemeral 

 series round the hill as opportunities for the numerous necessary visits 

 arose. Then one or two of the exceptionally difficult and doubtful 

 portions where exposures are wanting, and everything was hidden 

 beneath a continuous cloak of grass, were re-surveyed in company. 



Owing to a deficiency of exposures or of any clear physical feature, 

 it has been found impossible to determine with precision the limits 

 of the Dumortieria- to sj^inati-heds round the Rackledown projection, 

 for some little distance along the southern side of the escarpment 

 between East Dundry and Maes Knoll, and also for some little 

 distance east of the drinking-trough on the Chew Stoke road, | mile 

 east of Dundry village, on the northern side of the plateau ; and 

 the lines drawn on our map for these portions of the area must be 

 looked upon, therefore, as to a certain extent conjectural. 



In the western portion of the hill — i. e. west of the main Chew 

 Stoke road — owing to the absence or non-appearance of the Marlstone 

 Rock, the Toarcian base-line had to be defined by the bifrons-hed, 

 which, being too insignificant of itself to form an appreciable 

 surface-feature, made it impossible for us to do more than draw 

 in this line to a certain extent conjecturally : the chief evidence for 

 it being furnished by the presence, at a level of about 50 feet below 

 the base of the Aalenian Series, of the hi/rom-hed in springs, road- 

 cuttings, hillside scars, and our special excavations made at rhe 

 western end of the hill. 



Concerning the natural features of the surface-configuration of 

 Dundry Hill, the following remarks may be made : — 



The edge of the hill, which may be as much as 100 feet below 

 the highest ground on Dundry, is defined by rocks of Bathonian age 



