636 hkport— 1881. 



The courses of building stone are conglomeratic, and rest on eroded surfaces. The 

 Frodshani Beds are precisely similar to the soft upper and lower subdivisions of 

 the Bunter. 



The Waterstones, on the other hand, are allied to the Marls in ever)' respect, 

 even the sandstone-beds being easily distinguishable from those of the Basement 

 Beds, The striking contrast between the Waterstones and the Basement Beds is 

 well shown at Runcorn and Frodsham, where deep-red shales rest direct upon the 

 current-bedded sands of the Frodsham Beds. Upwards the Waterstones pass 

 quite insensibly into the Red Marls, and like them, coutaiu ripple-marks, sun- 

 cracks, so called rain-pittings, and the casts of rock-salt crystals. The last-named 

 appear first in the "Waterstones. 



The Waterstones, like the other subdivisions of the Trias, varv rapidlv in 

 colour. They are generally red, but near Kelsall are white, with green shales. 

 The Basement Beds at Helsby are brown, but at Manlev are white ; at Delamere 

 brown again, but once more white in the Peckforton Hills. The Frodsham Bed.s 

 change from red to white in a few 3'ards in the railway cutting at Runcorn, and 

 again near Frodshani and Overton. The Upper Mottled Sandstone goes through 

 every possible variation between red, white, and yellow, at Beeston Castle. These 

 changes show that no dependence can be placed on colour as a means of 

 identification. 



In Lancashire, previously surveyed by Mr. De Ranee, the base of the Marls 

 had been drawn at this line below the Waterstones, no subdivision of the Water- 

 stones from_ the Marls being possible, owing to Drift. The section in the Orrell 

 railway is similar to that at Runcorn, and the Basement Beds here and at Ormskirk 

 are of the same character as in Cheshire. In Liverpool the same sequence has 

 been made out by Messrs. De Ranee and Morton. 



Near Nottingham the same line has been observed by Mr. Aveline (• Geol. 

 Survey Memoir,' 2nd edition). Though the Basement Beds are thin, and in places 

 absent, the Waterstones are well-developed. Mr. Shipman (' Nottingham Nat. Soc. 

 Ann. Rep.' 1880) remarks on this overlap, and states that there is an appearance of 

 erosion between the Waterstones and the Basement Beds. The same observer 

 mentions the marked contrast presented by the Waterstones to the Basement Beds 

 at Alton in Staffordshire. 



The line therefore is persistent over a large area. The notion that there was 

 a perfect passage from the Basement Beds into the Marls arose from incorrect 

 mapping, by which the Waterstones were placed sometimes in the one, sometimes 

 in the other subdivision. At this horizon also the principal overlap in the Trias 

 takes place, for the Basement Beds thin out with the Bunter, but the Waterstones 

 and marls run on beyond so as to rest on Palisozoic Rocks. The change in the 

 character of the sediment, and the appearance of salt-crystals, show that at this 

 period a change in the physical geogi-aphy of the region took place, which led 

 to tranquil deposition of sediment and the concentration of brine in land-locked 

 basins. 



This line at the base of the Waterstones was taken by Ormerod and others as 

 the base of the Keuper, but in 1852 Prof. Hull drew the base below what then 

 came to be called the Keuper Basement Beds, because, firstly, there was no sign of a 

 break from this rock upwards; secondly, there was an apparent unconformity below 

 it. It has been shown that the first of these reasons will probably not hold good. 

 The second reason depends on evidence of unconformity which is not trustworthy. 

 The apparent unconformity visible at Ormskirk (' Triassic Memoir,' p. 87) is an 

 effect of current-bedding, and the evidence of denudation of the Bunter in South 

 Lancashire and Cheshire rests on the identification of horizons in the Upper 

 Mottled Sandstone by colour, which is now known to be untrustworthy. The 

 appearances of erosion below the Basement Beds are equally strong at other 

 horizons, for instance below the Pebble Beds in the middle of the Bunter. 



Considering the strong lithological resemblance of the Basement Beds with the 

 Bunter, and the similarity of its distribution, it must be reconsidered whether the 

 importance of the line between them has not been over-estimated, and whether 

 the line at the base of the Waterstones does not constitute a more important 



