Frof. Lehour — Recent Earthquahes on Coast of Durham. 513 



A. The infilling of tlie caverns by local gravels. B. The occupation 

 of the caverns by beasts of prey and by man. C. The formation of 

 the stalagmite. D. The breaking up of the stalagmite floor, and the 

 introduction of the Boulder-clay. The position of the caverns almost 

 at the crest of a ridge of Carboniferous rocks makes it clear that the 

 Boulder-clay could not have been introduced by streams ; therefore 

 the only conclusion 1 can arrive at is, that during a period of 

 great submergence, either during or subsequent to the Glacial epoch, 

 the material was introduced by marine action. Also that this sub- 

 mergence, and the subsequent elevation of the submerged area to its 

 present height of over 400 feet above sea-level, must undoubtedly 

 have taken place since the caverns were occupied by man and by the 

 extinct animals. 



\T, — On some Eecent Earthquakes on the Durham Coast and 

 THEiK Probable Cause.' 



By G. A. Lebouk, M.A., F.G.S., 

 Professor of Geology in the Durham College of Science, JN'ewcastle-upon-Tyne. 



SINCE the latter end of 1883 up to the present time (Sept. 1885) 

 the inhabitants of certain portions of the town of Sunderland 

 have been much disturbed by a series of small but distinctly sensible 

 earth-shakes, which have caused considerable discussion in the local 

 press and elsewhere. These shocks were chiefly felt in that quarter 

 of the town known as the Tunstall Road, but were not absolutely 

 limited to that locality. They were accompanied by rumblings — 

 sometimes dull but often loud — by the rattling of crockery and 

 furniture, and frequently by very distinct shakes of the entire frame-" 

 work of buildings. Often the shocks have, at night, waked up and 

 terrified the sleeping inhabitants. 



The probable origin of these disturbances has naturally been much 

 canvassed, and blasting in quarries, shot-firing in collieries, and the 

 passing of railway trains, have in turn been accused of causing them, 

 and, on examination, have been found " not guilty." At the present 

 time there is no doubt whatever that the shocks are due to some 

 •natural cause. As to what that natural cause may be, there is per- 

 haps room for difference of opinion. 



My friend, Mr. M. Walton Brown, of the Coal-trade Offtces at 

 Newcastle-upon Tyne, in a paper read in 1884 before the North of 

 England Institute of Mining and Mechanical Engineers, refers to the 

 Sunderland shocks as being genuine earth-tremors ; but I think that 

 their extremely local character — setting aside many other points 

 inconsistent with this view of their origin — is conclusive against 

 this being so. 



In another paper read at the same time as Mr. Walton Brown's 

 before the same Institute, I brought forward a number of facts 

 tending to connect the phenomena above referred to with certain 

 peculiarities in the geological structure of the district. Since that 



1 Read hefore the Geological Section (C) of the British Association, Aberdeen, 

 September, 1885. 



DECADE III. VOL. II. — NO. XI. 33 



