1847.] GUMMING ON THE GEOLOGY OF THE CALF OF MAN. 179 



In contending for the preservation of that system in its unity, I 

 in no way detract from the very great merit of the researches of 

 my friend Professor Sedgwick in developing the physical structure, 

 dislocations, slaty impress, fossil characters and other phaenomena of 

 the rocks of North Wales, Cumberland and Westmoreland. 



As already stated, I formerly hoped he would also point out in 

 their lowest division the existence of a distinct zoological type which 

 would have entitled those rocks to a separate name ; but having 

 failed to do so, it seems to me manifest, that his " Cambrian " cannot 

 now be sustained by dismembering a fossiliferous system which has 

 been so long established, so largely developed, and so widely applied 

 over the world as the Silurian. Whether geologists will use the word 

 '•Cambrian" in reference to still older and often unconformable 

 greywacke lying beneath all the beds with Silurian fossils, it is not 

 for me to determine. My chief object in this communication is to 

 explain how, by the progress of research, the protozoic types of 

 various parts of northern Europe, including North Wales, have 

 been shown to be true equivalents of the lower part of a natural system 

 which I proposed twelve years ago, and which geologists of various 

 countries adopted after a careful scrutiny of the evidences on which 

 it was established. 



2. On (he Geology of the Calf of Man. By the Rev. J.G.Cumming, 

 M.A., F.G.S., Vice-Principal of King William's College, Isle of 

 Man. 



The Calf of Man is an islet of about 800 acres in superficial extent, 

 situated at the south-western extremity of the Isle of Man, and se- 

 parated from it by a narrow channel, in breadth not more than 500 

 yards, called "the Race" or "Sound" of the Calf. Nearly in the 

 centre of this channel, but rather towards its northern side, lies the 

 small rocky islet of Kitterland, between which and the Isle of Man 

 the channel is fordable at low water, and between it and the Calf 

 islet the passage is rendered dangerous by several sunken rocks, the 

 tide rushing through the channel at certain periods of ebb and flow 

 at the rate of nine miles per hour. 



Section (1.) 



