LIASSIC ROCKS OF THE CARLISLE BASIN. 



297 



Grinsdale they lie upon the upper white ones. In consequence of 

 this- decided unconformity the Stanwix Marls are here classed as 

 Keuper. 



And there seems to me to be little doubt that the Lias, in its turn, 

 rests unconformably on formations all of which are unconformable 

 to each other — the Gypseous Shales, the Kirklinton Sandstone, and 

 the Stanwix Marls. But as in this case it is barely possible, though 

 not, I think, probable, that the Stanwix Marls may overlap the two 

 lower formations and underlie the Lias throughout its area, the 

 possibility seems worth mentioning. 



In this paper such facts only have been brought forward as 

 seemed necessary to establish the true relations of the various for- 

 mations to each other, fuller details being reserved for a forthcoming 

 memoir. 



Note on the Lias. April 25, 1881. 



Since writing my paper, my attention was called by my friend 

 Mr. H. B. Woodward to a passage in a paper by Rev. J. E. Cross 

 " On the Geology of North-west Lincolnshire " (Quart. Journ. Geol. 

 Soc. vol. xxxi. p. 116). Mr. Cross remarks that in the neighbourhood 

 of Appleby he has not been able to detect any Rhsetic fossils, though 

 he has searched diligently for them. He says, " the first strata 

 next above the Keuper are those which contain Ammonites angulatus 

 and A. Johnstoni" He also remarks that A. angulatus has the 

 greater range, and extends throughout a zone of 150 feet or 

 more. 



In Cumberland A.Johnstoni must have a range fully equal to that 

 of A. angulatus in North-west Lincolnshire. 



In a letter received from Mr. Cross, dated February 22nd, 1881, 

 he states that he has not since detected any Rhsetic fossils in the 

 above-mentioned locality, but that, as they may be seen both near 

 Gainsborough on the south and across the Humber on the north, it 

 is very possible that they nevertheless exist there. He also remarks 

 that as U A. angulatus is one of the most persistent of Ammonites in 

 its own place, and A. Johnstoni, whenever it appears, ranges from 

 the middle of the A.-angulatus-heds to strata below those in which 

 A. angulatus is ever seen, I think if you find A. Johnstoni and do 

 not find A. angulatus, you must be below the A.-angulatus-be&s 

 altogether." 



Prof. J. W. Judd, in his paper on " The Secondary Rocks of Scot- 

 land " (Quart. Journ. Geol. Soc. vol. xxxiv. p. 697), remarks that the 

 zone of Avicula contorta does not appear to be distinctly developed 

 in the West Highlands, while the Infralias (Planorbis- and Angulatus- 

 zones) attains a thickness of from 150 to 200 feet. 



EXPLANATION OF PLATE XL 

 Sketch Map showing the rocks of th p Carlisle basin: scale 4 miles to 1 inch. 



