Chas. Davison — British Earthquakes, 1891. 299 



to graduate downward by interbedding into the great series of barren 

 greywackes and argillites, which we call the Ingleton Green Slate 

 Series ; so that the upper and the lower sections are almost 

 inseparable. 



Like Mr. Marr, we were all of us at first very much struck by 

 the remarkable difference in lithological character between these 

 sedimentary rocks of Ingleton and the tuffs and lavas of the Lake 

 District. Mr. Aveline, whose authority in such matters no geologist 

 will question, repeatedly expressed the opinion, as far back as 1874, 

 that he could see no difference between this Ingleton Green Slate 

 Series and the Longmyndians. Nor can I. Nor is there any differ- 

 ence between them and the rocks of the Scottish Central Highlands, 

 except that the latter rocks have undergone plutonic metamorphism, 

 which the Craven rocks have not. But then, on the other hand, one 

 great series of greywackes is very much like another, and much of 

 the Coniston Grit, as Mr. Marr knows better than most men, is 

 hardly distinguishable in lithological character from much of the 

 Ingleton rocks. 



I see no difficulty in regarding the Ingleton rocks as old sediments 

 like the coarser part of the Milburn Eocks, into which marine 

 currents have swept the detritus from the contemporaneous denuda- 

 tion of the maritime volcanoes to the north. 



In conclusion there is one point that Mr. Marr has not dwelt upon 

 at as great length as his knowledge of the subject would have 

 warranted. It is this : — the most widely-spread types of Ordovician 

 rocks in the north-west of England must not be looked for in the 

 Lake District proper, but in the areas where deeper- water conditions 

 obtained outside of it. The persistent types are to be found, not in 

 Mid-Cumberland, but in Craven, and within the Cross Fell Inlier. 



Ill — On the British Earthquakes of 1891. 



By Charles Davison, M.A. ; 



Mathematical Master at King Edward's High School, Birmingham. 



COMPAKED with that of the year before, the British seismic 

 record for 1891 is somewhat meagre. It includes a slight 

 earthquake felt in North Cornwall on March 26, several at Inver- 

 garry, Ardochy, and Loch-hourn Head in Inverness-shire ; and one 

 other, believed to be that of an earthquake, at Bournemouth on 

 October 25. The remarkable series of earthquakes felt between 

 November 15 and December 14, 1890, in the district round Inverness 

 seems to have ended at the latter date ; for Mr. J. Birnie, a very 

 careful observer residing at Balnafettack, informs me that he has 

 felt none during the past year ; and his evidence is especially 

 valuable, since the epicentra of nearly all the shocks must have 

 been close to that village. 



N. Cornwall Earthquake : March 26, 1891. 

 Time of occurrence, about 11 h. 30m. ; Intensity, IV. ; Epicentrum, 

 lat. 50° 40' N. ; long. 4° 36|' W., i.e. 4. miles N. 35° E. of Camelford. 



