574 Mr. J. Beete Jukes and the Rev. Samuel Haughton on the 



boundary of the area, as drawn on the map, has an average direction of N. 42° E., 

 which may be considered as N. E. and S. W. 



B. — The Cambrian district of North WicUow commences about four miles 

 north of Rathdrum, and extends to the valley of the Dargle at least, having a 

 length of seventeen miles, and a width of seven or eight. Its western boundary, 

 although rather irregular, has a strike of about N. 27° E. (nearly N. N. E. ), whilst 

 its south-eastern boundary, which is, however, believed to be a fault, runs 

 N. 53° E., or N. E. ^ E. 



This district forms a much greater extent of lofty ground than that of "Wex- 

 ford, having several hills of more than 1000, and one, namely the Great Sugar 

 Loaf, of 1660 feet in height. 



Its beds, accordingly, are often well seen, and several good sections, such as 

 that of Bray Head, that of the Rocky Glen near Kilmacanoge, and those of Glen- 

 ran, the Devil's Glen, and other places near Ashford, are to be seen in it. 



In these and other sections continuous series of beds, several thousand feet 

 in thickness, are shown, and the more conspicuous members of them may some- 

 times be traced across the country, continuously along the strike, for two or 

 three miles, preserving the same dip and strike for that distance pretty steadily. 

 In every case, however, it has been found impossible to follow them out for 

 a greater distance ; sudden and entire changes in the beds occurring, probably 

 in consequence of great faults; or else an utter change in the direction both of 

 dip and strike, and a confusion in the position of the rocks, arising apparently 

 from numerous and complicated folds and contortions, combined with disloca- 

 tions, so that, even if all the rocks were bared for an inspection, it would appa- 

 rently be quite impossible to disentangle the confusion. 



The most probable conclusions at which we can arrive from the study of 

 these two Cambrian districts is, that in each case the lower beds are on the south 

 and east, and the upper ones on the north and west, but even this vague con- 

 clusion is a very uncertain one. (See Sections 1 and 2.) 



Two small slightly detached districts of Cambrian rock are to be mentioned 

 in North Wicklow, the one forming Carrick Mountain, on the south-east of the 

 area B, and the other making Carrickgolligan on the north-west of it. 



The south-easterly one commences a little south of Ashford, and is six miles 

 long, and not quite a mile in its greatest breadth. Carrick Mountain, 1260 feet 

 in height, is its loftiest point. Both its beds and boundaries strike N. 53° E. 



