40 



J. W. E. DAVID — GLACIAL ACTION IN SOUTH 



Fig. 1. — Sketch Map of South Brecknockshire and East Glamorgan- 

 shire. (Scale, \ inch to 1 mile,) 



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from the Rhymney and Taff-fechan valleys to a line drawn from 

 Cowbridge to Ystrad-fellte, in the Neath valley. Its extent is about 

 200 square miles ; but only a small part of it, viz. the Ely valley be- 

 low Llantrisant, has been examined by the author at all thoroughly. 



2. Surface-Phenomena. 

 There are six principal kinds of evidence of glacial action in this 

 area : — 1. Erratics ; 2. Boulder- clay; 3. Polished, smoothed, shattered 

 and contorted rock-surfaces ; 4. Grooved and striated rock-surfaces ; 

 5. Glaciated contour of country ; 6. Contorted bedding in drift. 



