GUMMING ON THE ISLE OP MAN. 321 



cation of the ancient shore. I have not as yet succeeded in obtain- 

 ing any fossils from the Old red sandstone of any portion of the 

 island. As far as I have observed, there does not appear to have 

 been any disturbance of the Old red sandstone prior to the depo- 

 sition of the overlying limestone. 



The overlying limestone is always conformable to the subjacent 

 conglomerate ; and indeed the passage of the latter into the former 

 is often so regular, that it is difficult for a few feet to say to which 

 formations the beds belong. There appears to be a gradual abstrac- 

 tion of the larger quartz pebbles and we obtain a brown arenaceous 

 and pebbly limestone for a few feet containing organic remains; 

 these beds soon pass into the regular series of dark limestone and 

 shales, to which I am more particularly anxious to direct attention. 



The small patch of limestone which once existed to the north of 

 Peel on the surface of the Old red sandstone as it dips rapidly 

 seaward, has some time since been wrought out, and it is difficult 

 now to determine absolutely whether it belonged to the mountain 

 limestone, or was merely a thin band of cornstone ; but there are 

 strong indications of the mountain limestone existing not far out at 

 sea, as the shore to the north abounds with boulders not much 

 rounded, and with pebbles containing fossils similar to those of the 

 southern limestone basin of the island. 



I have before observed, that the limestone of the south of the 

 island has generally been regarded as of the same age as the lower 

 Scar limestone of Yorkshire. It will however I think become a 

 question whether the greater portion should not be considered as of 

 a more ancient date, and whether, if not merging into the Devonian 

 period, it is not at least of the same antiquity as the lowest Northum- 

 berland shales and the oldest carboniferous beds of the south of Ire- 

 land. 



As the different beds of limestone crop out very regularly on all 

 sides of this southern basin, the order of succession in the lower por- 

 .tion is made out without difficulty, especially as each bed has some 

 characteristic fossil. Thus we find in the lower beds, and within a 

 few feet of the old red conglomerate. Cirrus rotundatus, Bellerophon 

 ccpertu$, Creseis JForbesii, Productus hemisphcericus, Or this Sharpei 

 (the O. umhraculum of Portlock's Survey), a species of Posidonia, 

 Cyaihophyllum rtiegastoma^ Calamopora rarnosa, and Phillipsia 

 Kelli (of Portlock's Survey). Above these are very large specimens 

 of Turhinolia fungites^ and a large coral apparently very similar, but 

 recognised by Count Keyserling as Caninia gigantea of Michelin. 

 We have also the Leptccna papilionacea^ and lastly, amidst a great 

 dearth of organic remains, the few specimens of Goniatitcs Henslowi 

 and Nautilus comjilanatus which have hitherto been discovered. 

 By the assistance of a fault in the centre of the basin we can arrive 

 at a fair estimate of the general thickness of this lower series of 

 dark limestone and shales, which does not thus appear to be more 

 than 160 feet at the deepest accessible part. The i)assagc however 

 from these beds into the superior light-coloured and highly fossili- 

 ferous limestones of Poolvash is not very distinct, the basset edge 



