1864.] LOGAN LAUEENTIAN FOSSILS. 45 



3. On the Eecext Earthquake at St. Helena. 

 By Governor Sir C. Elliot, K.C.B. 



[Communicated by the Colonial Secretary through Sir C. Lyell, Bart., 

 F.R.S., F.G.S.] 



[Abstract.] 



This earthquake, which is stated to be the fourth that has occurred 

 during the two centuries that we have been in the occupation of the 

 Island, occurred at about 4h. 10m. a.m. on July 15th, and in this 

 paper Sir C. Elliot described the nature of the shock and the cir- 

 cumstances attending it. 



November 23. 



"William Stephen Mitchell, Esq., of Gonville and Gains College, 

 Cambridge, was elected a Fellow. 



The following communications were read : — 



1, On the OccuRREKCE of Organic Remains in the Laurentian Rocks 

 of Canada. By Sir W. E. Logan, LL.D., E.R.S., E.G.S., Director 

 of the Geological Survey of Canada. 



The oldest-known rocks of ISTorth America are those which compose 

 the Laureutian Mountains in Canada and the Adirondacks in the 

 State of jNTew York. By the investigations of the Geological Survey 

 of Canada, they have been shown to be a great series of strata, 

 which, though profoundly altered, consist chiefly of quartzose, 

 aluminous, and argillaceous rocks, like the sedimentary deposits of 

 less ancient times. This great mass of crystalline rocks is divided 

 into two groups, and it appears that the Upper rests unconformably 

 upon the Lower Lauren tian series. 



The united thickness of these two groups in Canada cannot be less 

 than 30,000 feet, and probably much exceeds it. The Laureutian 

 of the West of Scotland also, according to Sir Eoderick Murchison, 

 attains a great thickness. In that region the Upper Laurentian, or 

 Labrador series, has not yet been separately recognized ; but, from 

 Mr. McCulloch's description, as well as from the specimens collected 

 by him, and now in the Museum of the Geological Society of London, 

 it can scarcely be doxibted that the Labrador series occurs in Skye. 

 The labradorite and hypersthene-rocks from that island are identical 

 with those of the Labrador series in Canada and New York, and 

 unlike those of any formation at any other known horizon. This 

 resemblance did not escape the notice of Emmons, who, in his de- 

 scription of the Adirondack Mountains, referred these rocks to the 

 hypersthene-rock of McCuUoch, although these observers on the 

 opposite sides of the Atlantic looked upon them as unstratified. In 

 the 'Canadian Naturalist' for 1862, Mr. Thomas McFai-lane, for 



