The Section at the High Force, Teesdale

Abstract

I t has been my duty, in the course of Survey work, to examine the ground near the High Force. In doing this, several facts have come to light which will, perhaps, he not uninteresting, as they refer to a somewhat classical district, and correct ideas which have been hitherto erroneously held on the authority of Phillips's section at the High Force. These ideas have lately acquired a special importance from their hearing on the subject of “selective metamorphism;” and in correcting them I may be helping, in some small degree, to clear the way for the formation of a theory to satisfactorily account for those instances of selective metamorphism which stand undoubted. In Phillips's ‘Geology of Yorkshire’ (1836), part ii. pp. 78, 79, the following passage occurs in connexion with the section at the High Force:-“Shale or plate is so much altered at the High Force in the relation of the joints that most persons mistake a part of the prismatic masses, really composed of metamorphic shale, for trap, and suppose the latter to rest on limestone. The true series is as follows, proceeding downwards:— “ a. Basalt, rudely prismatic, grey with lichen. b. Thin plate, not very much indurated. c. Bed of plate, subprismatic. d. Beds of plate, laminated. e. Thin limestone bed, with a superficial layer of pyrites. f. Bed of hard pyritous limestone. g. Several beds of common dark limestone, with white shells and corals.” (Among the Dalesmen the word “plate“ is equivalent to “shale,” and the basalt referred to is part of the