I. I ntroduction . The glaciation of the area herein described first interested me while re-surveying the Longtown Sheet of the Geological Survey Map (N.S. Sheet 11) and the northern part of the Carlisle Sheet (N.S. Sheet 17). In this area there was evidence of two glaciations, and the later of these appeared to have emanated from the Southern Uplands of Scotland. The retreat of this ice-sheet was followed westwards along the northern shores of the Solway Firth in my vacation during the years 1921–22. During the year 1923, the first year of the re-survey of the Brampton Sheet (1-inch N.S. 18) by the Geological Survey, a wealth of glacial retreat-phenomena of the earlier glaciation was discovered near Brampton, and briefly described in the Summary of Progress for that year. The evidence for a westward retreating ice-sheet was incontestable, but the direction of the drainage of the impounded glacier-lakes suggested the operation of Lake District rather than Galloway or Southern Upland Ice. The composition of the drift also threw grave doubts upon the accepted Scottish origin of this ice-sheet. Nevertheless, there were some puzzling features connected with the distribution of the erratics and the drift. To cite but one example: although Lake District erratics, principally lavas and ashes of the Borrowdale Volcanic Series, predominated in the drift, suggesting Lake District ice moving down Edenside, yet the drift did not contain a single boulder of Shap granite, a boulder to be expected from such an ice-movement. Therefore, before I committed myself to a