Vol. 51.] MR. J. E. MARR ON THE TARNS OF LAKELAND. 



45 



exit, but on each side of this are enormous masses of moraine ex- 

 tending downwards for hundreds of feet into the Langstrath Valley. 

 These are peril aps the finest moraines in the district, and they have 

 entirely concealed any marked signs of the original valley, though 

 the trend of the contour-lines suggests that this valley ran to the 

 west of the present stream. 



The Langstrath Valley itself takes its name from the long stretch 

 of alluvial flat which occupies its floor for a considerable distance. A 

 deep narrow gorge through rock at the lower end has drained the old 

 lake, which was probably ponded up by the mass of moraine-material 

 lying west of the gorge and blocking the valley. If this gorge were 

 filled with drift we should find a lake above it of the character of 

 Burnmoor Turn. 



At the foot of the Rosthwaite alluvial plain a mass of drift is 

 plastered against the rock by the roadside : this drift probably once 

 extended across the Borrowdale Valley and caused a lake, which was 

 drained by the stream cutting through the drift. 



VII. Tarns between Borrowdale and Thirlmere. 



"Watendlath Tarn, 847 feet above sea-level and 46 feet deep, was 

 once much larger than at present. There is rock at the exit, and 

 much rock on either side. A great mass of drift is plastered against 

 the east side of the valley, and may have filled the old valley, but on 

 mounting some way above the tarn I saw indications of the possible 

 existence of a moraine-filled depression on the east side. The time 

 at my disposal did not allow me to make as full an examination of 

 this tarn as I could have wished, for, owing to the presence of the 

 hamlet and of wall-enclosed fields, it is difficult to move about 

 rapidly. 



Fig. 10. — Plan of Harrop Tarn. 



[For Explanation, see p. 47.] 



