Vol. 52.] ON THE UPPER PORTION OF DUNDRY HILL. 705 



VIII. Remarks on the Important Features of the 

 Dundrt Strata. 



Some of the more striking features of the Dundry rocks call for 

 special notice on our part ; and with these remarks we shall have a 

 few words to say about the contemporaneous deposits in. other 

 districts which are comparable with those of Dundry. 



(1) The Marlstone Rock. 



The first intimation which we had of the presence of the 

 Marlstone Rock at Dundry, or rather of the existence of a deposit 

 laid down during the spinati hemera, was in receiving from a quarry- 

 man a very good specimen of Pleuroceras afT. nudum, (Quenstedt). 

 This man said that it came from the ' Ironshot Oolite ' in one of the 

 quarries on the hilltop : it certainly came from an ironshot oolite ; 

 but the colour and softness of the matrix showed that it was not the 

 Ironshot Oolite, — the rock deposited during the Sauzei hemera. 

 Further, the specific and generic determination convinced us that 

 the species lived contemporaneously with Pleuroceras spinatum. 

 How or where the quarryman obtained it we know not, and we 

 have never been able to learn. We then knew of no Marlstone 

 exposed at or near Dundry itself ; and we know of none now to the 

 west of the main road. 



Since then we have found Marlstone Rock ; first at Maes Knoll on 

 the western side of the camp, 1 towards the base of the steep escarp- 

 ment, well within what is marked g 5, Inferior Oolite, in the Geolo- 

 gical Survey map. Next we found the rock well shown in a 

 farmyard by the side of the road at East Dundry : and here again 

 the line for Inferior Oolite on the Survey map is carried well below 

 the Marlstone outcrop. Further, the Marlstone Rock crops out 

 on the hillside below Watercress Farm, and it has been disclosed 

 in field-drains opposite the Rookery. On the northern side of the 

 escarpment from New Down Lane by East Dundry to Maes Knoll, 

 it is shown at various points in the fields — often slipped or tilted 

 blocks — and the ' bifrons-heds * are occasionally shown resting upon 

 it (see Section VI a. p. 684). Immediately west of the corner of 

 the little spinney south-west of Maes Knoll Tump the Marlstone 

 Rock is well shown as a massive bed 2 feet 10 inches thick ; and 

 the same bed, as slipped blocks, is seen again for some distance along 

 the southern side of the spinney. Yet again, in the lower part of 

 this wood it is exposed in several places in situ, and once more 

 near the base of the escarpment 70 yards east of the spinney. 

 For the sections of these latter exposures see p. 686 — Section of 

 Maes Knoll. In addition to these places we have found outcrops 

 of the Marlstone Rock at several other points, but only in the 



1 It was a brown ironshot stone and was conglomeratic, containing derived 

 lumps— among them a blue stone with crinoids. It yielded belemnites, and 

 what was determined as Pseudopecten cequivalvis. 



