lxxvi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May I906, 



structure of the area : although, as I hare already stated them in 

 the ' Notes ' to which reference has been made, the outline may 

 be brief. 



It is now generally conceded that the junction between the 

 Skidd aw Slates and the Borrowdale Series of rocks is, in nearly 

 all cases, faulted, and that the fault-plane has an inclination 

 approaching the horizontal. This is abundantly evident from an 

 examination of Clifton Ward's maps, and the low angle of the 

 plane of junction was recognized by Mr. Dakyns so far back as 

 1869. We have reasons for supposing, however, that this plane is 

 not one of overthrust, but that an overthrust occurs at a lower 

 position; namely, at the base of the Skiddaw Slates, and is therefore 

 but little exposed in the district ; although we refer the position of 

 the Drygill Shales of Caradoc age, among the older rocks of the 

 Caldbeck Pells, to the action along this overthrust. According to 

 our views, the rocks of the district have been pushed in a general 

 northerly direction along this plane, and the greatest movement 

 occurred in the Skiddaw Slates : while the rocks of the Borrowdale 

 Series, though moving northward, lagged behind the Skiddaw 

 Slates, and the Upper Slates in™ turn lagged behind the rocks 

 of the Borrowdale Series. We have, therefore, described the 

 fault which separates the Skiddaw Slates from the Borrowdale 

 Series of rocks, and another with higher inclination which we 

 believe to occur between the Borrowdale Series of rocks and 

 the Upper Slates, as ' lag-faults.'" So far as the present physical 

 features are concerned, the question as to whether these faults are 

 overthrust s or lag-faults is unimportant. The part played by 

 another set of faults, to which we referred as ' tear-faults,' in 

 controlling the production of some of the physical features of the 

 district is, on the contrary, of very great import ; and some attention 

 must here be devoted to the nature and extent of these ' tear-faults,* 

 which appear to correspond with the blatter of Suess. 



One may regard the rocks of the three divisions as three strips 

 moving onward during the period of earth-movements, and each 

 of these strips is divisible into minor bands, which are specially 

 marked in the case of the rocks of the Borrowdale Series and of the 

 Upper Slate-Group. But different parts of the same strip moved 

 at different rates, and where the rocks were too rigid to adapt 

 themselves to the different rates by bending, one portion of a strip 



