J. Q. Goodchild — Deutozoic Rocks of North Britain. 60 L 



not be possible that remnants of some of these may also exist on 

 the English side of the Border, perhaps concealed beneath newer 

 formations, or, it may be, even exposed at the surface in places 

 where their identity has not hitherto been recognised. 



As regards the possibility of these rocks occurring in the Lake 

 District, it should be borne in mind that there are two lines of 

 evidence which clearly point to the existence, in former geological 

 times, of andesite volcanic rocks of the types which occur so widely 

 throughout the Caledonian Old Eed. One of these is, as I pointed 

 out many years ago, the fact that the Upper Old Eed of North 

 Cumberland partly consists of pebbles and blocks of these lavas. 

 These andesite pebbles are so abundant in some places, as, for 

 example, near Melmerby, that I have long entertained the belief 

 that a large tract of these Caledonian Old Eed lavas must exist at 

 no great distance, they being covered, of course, by rocks of later 

 formation. Then, again, there is the well-known fact that several 

 of the granite bosses and Elvan and Porphyrite dykes of the Lake 

 District are of later date than the cleavage of the rocks around 

 them, and are later even than the great denudation which preceded 

 the formation of the Upper Old Eed. Furthermore, fragments of 

 these granites and their apophyses, as already stated above, occur 

 in the conglomerates of the Upper Old Eed. Lastly, the close 

 resemblance in mineralogical constitution of these Lake District 

 granites to those of the South of Scotland, which can almost be 

 proved to represent the deep-seated parts of the cores of the 

 Caledonian Old Eed volcanoes, forms an additional link in the 

 chain of evidence which points to these Lake District granites 

 being contemporaneous with the later part of the Caledonian Old 

 Eed, and to their marking the sites of areas from which, at one time, 

 andesitic lavas must have overspread the districts around. 



During the past sixteen years it has been one part of my duty 

 to arrange for exhibition in the Edinburgh Museum of Science and 

 Art a very large series of Scottish Fossils, Minerals, and Eocks, 

 amongst which last figure very largely representatives of the 

 Scottish rocks of Devonian age. A large proportion of these rocks 

 I have also studied in silu, always regarding them when doing so 

 with considerable interest, as representing part of the series that 

 must, in some one place or another, fill up the great hiatus between 

 the Upper Old Eed and the Protozoic Eocks of Cumberland and 

 Westmoreland. Whenever a suitable opportunity has presented 

 itself, I have taken advantage of it to go carefully over the field 

 evidence presented by the district just named. There is one part 

 of the Lake District in particular to which I have devoted attention 

 at various times since 1873, and that is the part lying to the north 

 and north-east of Saddleback. A thick series of basic andesite lavas 

 with some tuffs occurs there. These pass unconformably beneath 

 the Lower Carboniferous Eocks to the north and east; and their 

 base, in the opposite direction, comes into contact with sedimentary 

 rocks which are certainly very low down in the Skiddaw Slate Series. 



