306 C. Damson — British Earthquakes of 1889. 



The needles of the fireclays may, however, be secondary and yet 

 not be derived wholly or even in part from the biotite. Some other 

 mineral, sphene for instance, may have been the parent, though, as 

 intimated in my paper, it does not seem so likely. 



If the rutile is not secondary, it must have been brought in with 

 the original sediment. I consider it may be looked on as shown 

 that it was not contained as such in the original mica. Whence 

 did it come ? Can anybody point to granites or gneisses containing 

 rutile-needles in the abundance required for these extensive deposits, 

 and containing them, moreover, not in the mica, the usual way in 

 which they do occur when seen at all ? If, in spite of all the 

 evidence on this head, it is assumed that some other rock and not 

 granite or gneiss was the source of these deposits, then what rock 

 can be suggested which supplied the rutile and the mica ? And if 

 it be supposed that this other rock supplied only a part of the total 

 materials, but all the rutile, then it would be still more interesting 

 to have that rock named. It is easy to say the needles came from 

 elsewhere ; but where did they come from ? 



The subject of the origin of the minerals in these special clays, etc., 

 is of much interest, because it may throw light on the genesis of 

 slates and phyllites, a question which has given rise to much 

 speculation and discussion and received great attention from some 

 of the leaders in petrological work. It is a somewhat difficult 

 subject to deal with, and I would be the last to think that my own 

 suppositions and theories are in any way proved to be more than 

 attempts at an explanation. I only venture to hope that they are 

 not quite out of harmony with the other evidence, which seems 

 so strong, as to the original nature of the deposits ; and to think 

 that if they are disputed, if the secondary nature of the rutile is 

 denied, some other definite source for it should be suggested, which 

 should at the same time harmonize with the other facts of the case. 



Newcastle-on-Tyne, June, 1891. 



VII. — On the British Earthquakes of 1889.^ 



By Charles Davison, M.A., 



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



{Continued from page 67.) 



2. Lancashire Earthquake : Feb. 10, 1889. 



Timeof occurrence, 22 h. 36m.: Intensity, VI. Epicentrum about 

 two miles N.N.E. of Bolton, half a mile west of the village of 

 Bradshaw. 



This interesting earthquake affected a district for the most part 

 thickly populated, and the accounts of it are consequently numerous. 

 In the newspapers mentioned below, records are given of observations 

 from 156 towns and villages, situated within a nearly circular area 

 about 55 miles in diameter. Considering the smallness of this area, 



1 The Map will appear with Part III. in the August Number Geol. Mag. 

 — Edit. Geol. Mag. 



