The Stratigraphy and Tectonics of the Cross Fell Inlier

Abstract

I. Introduction The Cross Fell inlier of older Palaeozoic rocks extends for 16 miles from Roman Fell to near Gamblesby, as a narrow belt of highly-disturbed country parallel to the north-north-west and south-south-east escarpment of the Westmorland and Cumberland Pennines. Its boundary on the east is formed by the outcrop of the gently dipping Carboniferous sediments which constitute the Alston Block (Trotter and Hollingworth, 1928). On the west, if we include as parts of the inlier certain blocks of greatly disturbed Carboniferous strata, the boundary is defined by the appearance of the down-faulted Permo-Triassic rocks of the Vale of Eden. These are folded into a gentle syncline, or series of synclines in echelon, devoid of complex folding and fractured by but few faults. Between these two bounding regions of quiet tectonic history, the inlier exhibits a complex maze of folds, faults, and thrusts which are not limited to the outcrops of older Palaeozoic rocks. For some distance to the north, faults and steep dips affect the Carboniferous formations east of the Pennine Fault; while south-eastward from Roman Fell the disturbances continue with undiminished intensity for seven miles or so until, east of Brough, some, at least, appear to merge into the Dent Fault system of earth movements. It is unnecessary, at this stage, to recall more than a few of the papers which deal with the Cross Fell area. Early work by Goodchild (1874, 1889) and by Nicholson and Marr (1891) made great advances in the stratigraphy of the area.