UPPER PORTION OF DUNDRY HILL. 197 



of the Cotteswolcl range plus " Upper Lias," are important ; 

 and then the thick mass of overlying clay (No. 26) ]3roved at 

 the other end of tlie hill to have been deposited during the 

 Dumortieri^i3 hemera, contemporaneously with the middle 

 part of the Cotteswold Cephalopod-bed. All these deposits 

 show a thickness of about 50 feet, which would have been 

 formerly called " Midford Sands and Upper Lias." 



The evidence concerning the deposits made during the 

 hradfordensis and Murchisona^ hemeree is not very satisfactory 

 here, but Zeilleria anglica (see Nos. 19 and 22) marks a very 

 definite horizon in Dorset^ ; it lived more or less contempo- 

 raneously with Ludivigia MurcMsonas, and perhaps died out 

 just before Lioceras hradfordense. 



Above the horizon of Zeilleria anglica, the next noticeable 

 datum-line is that of Sonninia aff. avails (Quenstedt). Be- 

 tween these two horizons are certain beds with species of 

 Hyjperlioceras in the upper part, and species of i]ie concavum- 

 type lower down. 



It is to be noted that the planed- off top, indicating denu- 

 dation, appears on the upper surface of a bed which we term 

 the ' Lower White Ironshot,' so that there' is here a distinct 

 non-sequence between the strata of the Sonninue hemera and 

 the strata which directly overlie them, viz. the strata of the 

 Garantianai hemera. This gap in the sequence is partly 

 filled by some strata met with in sections to be described 

 presently. But the point to be noticed is that the beds of 

 the 8oiininia3 hemera in the western part of the hill are not 

 capped by any representative of the Ironshot oolite. 



The thick freestone beds of Dundry yield a stone of con- 

 siderable economic importance ; they are capped by a few feet 

 of coralliferous stone and marl, which we have termed the 



^ See S. S. Backman, 'The Bujocian of the Sherborne District;' 

 Quart. Journ. Geol, Soc, vol. xlix. (1893), p. 489. 



