28 MONOGRAIH OF DURA DEN. 



and seems to pass insensibly into a yellow-coloured sandstone, 

 some blocks of which, indeed, are scarcely to be distinguished 

 from that rock. The position of the cornstone, therefore, 

 appears distinctly to be betwixt the red and yellow sandstones ; 

 and, accordingly, at Craigfoodie, although tilted out of its natural 

 position by the trap, it lies in the near vicinity of the yellow 

 beds of Dura Den, 



The cornstone, a little to the south of Parkhill, is curi- 

 ously tossed up under the western slope of Clatchart, over- 

 roofed by a mass of clinkstone trap of 200 feet thick, and 

 underlaid by the grey sandstone, which, again, is intermixed 

 with the trap whose point of contact exhibits their fusion into 

 each other. The cornstone and sandstone are pitched up 

 at an angle of twenty-three degrees, and the accompanying 

 marl-beds, wasted away, show the lines of stratification in beau- 

 tiful relief. There is a greenstone dyhe a few hundred yards 

 to the west, which crosses the ridge south and north, and clearly 

 manifests itself as the lever-power which has elevated the whole 

 huge mass of Clatchart, with its overhanging cliffs and sedi- 

 mentary foundations of Hme and sandstone. 



This limestone is hard, compact, and sub-crystalhne, and gene- 

 rally of a yellowish-green or grey colour. The structure is 

 concretionary ; some portions of it are cherty, containing chal- 

 cedonic veins and small globular cells, which are coated over 

 with mammillated reddish chalcedony ; but generally it may 

 be described as a compact concretionary deposit, with several 

 interposed beds of a green and red pyritous marl, and stained 

 on the surface with innumerable dentritic figures. At Newton 

 it assumes the appearance of a calcareous breccia, containing 

 nodules of chert and jasper ; while two miles to the north-east, 

 on the property of Clunie in Strathearn, it is of a soft friable 

 nature, known in the neighbourhood as " the marl pit," and 

 long used as such for agricultural purposes. No organic re- 

 mains have been detected in any of its numerous localities, 

 and the rock is nowhere observable but in very limited por- 



