SI 8 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



want of any mutual relation, or of any connexion with any other 

 earlier or later palaeozoic formation, would lead to the conclusion 

 that as a geologist he might be more profitably employed elsewhere, 

 while the collector of fossils would almost immediately fix upon the 

 limestone of Poolvash as the only spot likely to afford any valuable 

 addition to his cabinet. This, in fact, has been the case ; and, from 

 the circumstance of the Poolvash locality being rich in fossils*, and 

 these fossils coinciding for the most part with those of the lower 

 Scar limestone of Yorkshire, it has been at once assumed that the 

 carboniferous series of the Isle of Man was referable to the same 

 geological position. 



The object of the present communication is partly to correct so 

 erroneous an impression, by showing that there is in the island the 

 most distinct and perfect sequence from the carboniferous strata into 

 the old red sandstone to be met with in British Geology, and partly 

 to trace out the various circumstances connected with the deposition 

 of the different palaeozoic formations, especially in reference to mo- 

 difications produced upon them by intermitted igneous agency. 



The mere statement of the fact of a very extensive development 

 of this agency in the south-eastern basin of the island leads us to 

 expect ditficulties in the way of a correct geological history of that 

 district, and the difficulties are further increased by the circumstance 

 that the altered, disturbed, broken, and subsequently denuded beds 

 are almost entirely covered up by the boulder clay, gravel and sand 

 apparently of a very recent geological period. 



A residence on the spot for nearly four years has enabled me, by 

 carefully observing, comparing and connecting the different phaeno- 

 mena presented at those points which are most exposed, as well as 

 by an examination and comparison of the fossils, to present the fol- 

 lowing account with a reasonable conviction of its offering at least 

 an approximation to the truth. 



To a person approaching it from the south, the Isle of Man pre- 

 sents the appearance of a broken, mountainous ridge, extending 

 from the Calf of INIan to Maughold Head near Ramsey, of wliicli 

 the highest points are Snaefell, in the north (2004- feet), and in the 

 south, South Barrule (1545 feet). Except from the Calf of Man 

 to Port-le-Murray, the descent on the south-eastern side to the coast 

 is gradual, but the coast itself is broken and precipitous wherever 

 the schists are exposed, and the cliffs in some places rise to the 

 height of 300 feet. Douglas Bay and the limestone district in the 

 neighbourhood of Castletown exhibit different geological and phy- 

 sical conditions. 



On the western side of the island, the descent from the mountain 

 ridge is generally very rapid from the Calf of Man to Dalby Point, 

 and excepting the inlet of Port Erin and Fleswick Bay, the whole 

 may be regarded as a continuous precipice from 400 to 1000 feet in 

 height. 



From Dalby to Kirk Michael the coast corresponds with that on 



* Mr. Gilbertson once observed to me that it was by far the most productive 

 place he had ever seen. 



