64 GEOLOGICAL FORMATIONS NEAR EMBLETON 



nearly a thousand feet higher than it occupies at the locality 

 here specially under notice. Indeed, even close to Embleton, 

 the Whin Sill varies considerably in position, and at one part it 

 rises above the Great Limestone, while within a mile or so it 

 descends some hundreds of feet lower in the Carboniferous 

 rocks. 



Mr Clough, of the Geological Survey, many years ago 

 brought forward trustworthy evidence in support of the view 

 that the Whin Sill is not intrusive, in the ordinary sense, but 

 that it occurs replaceively ; or, in other words, that it has taken 

 the place of an equivalent volume of the rocks it invades. The 

 writer of this note has also published much additional evidence 

 in corroboration of this view. Mr Clough's paper appears in 

 the Geological Magazine, decade ii., vol. xii., pp. 434-447 (Oct. 

 1880); and the later one referred to is in the Proc. Roy. 

 Soc, Edin.,' vol. xxv., pt. iii., pp. 197-226 (1904.) 



As the mode of occurrence of the Whin Sill presents many 

 features that are of interest to the student of the geology 

 of Northumberland, those persons who care to look into the 

 matter may be well to refer to one, or both, of these papers, in 

 which the actual mode of occurrence of these rocks is described 

 in detail. In both of these papers will be found suggestions 

 regarding the means by which this replacement of the country 

 rock by one of a different character may have been brought 

 about. 



In the large quarries on the North-east side of Embleton 

 village, where the Whin Sill is made into setts, there are 

 several features of interest which may well be recorded here. 

 Firstly, some parts of the Whin envelop detached blocks of 

 the sedimentary rocks through which it has made its way. 

 Amongst these some large fragments of limestone, now con- 

 verted into coarsely crystalline marble, are to be seen. Further 

 reference to this will be made presently, when dealing with the 

 rocks in Queen Margaret's Cove. The columnar jointing of the 

 Whin is, of course, as evident as usual ; but the quarries have 

 not yet been worked far enough to the East to enable one to 

 see whether the joints become less evident as the rock is 

 followed away from the surface. The weathering of the Whin 

 is shown here most admirably. It is difficult, at first, to believe 

 that the tough, dark blue rock from the interior of the quarry 



