Vol. 52.] ON THE UPPER PORTION OF DUNDRY HILL. 707 



partly, no doubt, owing to the break-up of the bifrons-bed and 

 redeposition, whereas the deposit during the same length of time at 

 Frocester Hill, ascertained by S. S. Buckman by some recent measure- 

 ments, is as much as 264 feet in thickness. 



With regard to the rest of the Cephalopod- or Blue Ironshot-bed of 

 Dundry Hill, it may be noted that only the deposits of the striatuli 

 and dispansi hemerae are contemporaneous with the Cotteswold 

 1 Cephalopod-bed ' ; that they are equivalent only to the lower 

 portion of that bed, because the Cotteswold Cephalopod-bed shows 

 deposits made during the following hemerae : striatuli, dispansi, 

 Dumortierice, Moorei, aalensis — so that it is equivalent in point of 

 time to the Blue Ironshot-beds (upper part), the Dumortieria-beds, 

 and the basement portion of the limestone series of Dundry Hill. 



(3) The Dumortieria-beds. 



It is certainly rather singular that the inappropriate nature of 

 the term * Midford Sands,' from a lithological point of view, should 

 be shown by a locality so close to Midford as is Dundry Hill. The 

 distance from Midford to Maes Knoll is only 10 \ miles ; yet 

 the deposit which would be called ' Midford Sands ' at Dundry is 

 a clay called by us the l Dumortieria-beds,'' resting upon a thin 

 ironshot limestone, and this latter deposit is contemporaneous with 

 some 30 feet of the lower portion of ' the Sands ' at Midford. 



With a thickness of some 50 to 60 feet the clays of the Dumortieria- 

 bed are to be found all round Dundry Hill, immediately below the 

 Limestone Series or so-called ' Inferior Oolite ' ; and they may be 

 known by such surface-indications as fruit-trees, springs of water, 

 and so on. They yield a good pasture, and thus, instead of the fir- 

 trees and waste land which occupy the sandy slopes of the 

 Cotteswold Hills, there are, at Dundry, grass-fields and occasional 

 orchards at about the same geological level. 



The Dumortieria-beds are, in point of date, contemporaneous with 

 the middle portion of the Cotteswold Cephalopod-bed, and, judging 

 by the evidence at North Stoke 1 near Saltford, with the upper part 

 of the Midford Sands. 



But we must note that the term ' Midford Sands ' has been used 

 in two different senses. It is employed in a wide sense to embrace 

 various non-contemporaneous sandy deposits laid down from the 

 latter part of the bifrontis hemera until the opalini hemera in- 

 clusive ; while in its restricted sense it is only a local name for 

 certain sandy beds in the neighbourhood of Bath, of the date of the 

 dispansi hemera so far as the earlier part is concerned, and the 

 later portion — judging by the evidence of North Stoke — of the 

 date of the succeeding Dumortieria? hemera. Taken in a restricted 

 sense, the Midford Sands are well represented at Dundry by a 

 thickness of 50 to 60 feet of strata, — which is very different from 

 what our predecessors have stated ; but at Dundry they cannot be 



1 North Stoke is 7 miles eastward from Maes Knoll. 



