306 D. Mackintosh — The Drifts of the Lake District. 



simile of many of tlie smoothly sculptured rocks one may see in all 

 limestone districts, where the irregularly pitting and roughening 

 action of rain-water and frost has not obliterated the evidently 

 ground-out basins and channels. On the hill-slopes between Silver- 

 dale Station and Yealand, and in many other places around More- 

 cambe Bay, the Silurian grit pebbles may still be found in the 

 hollows they once ground out. Under drift the sculptured lime- 

 stone surfaces often become decomposed, while in the open air, in 

 situations where rain-water innocuously runs off, they have remained 

 nearly intact. 



Valley of the- Duddon. — Beyond the northern boundary of the 

 granitic drift stream above described, and on the way to Thwaites, 

 there are immense boulders of felspathic breccia, ashes, and por- 

 phyry. W. of Green the strise run E. SC N. I have elsewhere 

 noticed the great pinel knoll near Green. About Thwaites there 

 are many knolls and slope-coverings of pinel, with boulders up to 

 eight feet in average diameter. Here, and all along the W. side of 

 the Duddon estuary, there is much green, grey, and blue porphyry, 

 in situ, along with ribboned or banded felspathic slag, felspathic 

 breccia and felspathic ashes ; and a tributary ice-laden current may 

 have carried boulders of these rocks into the great drift-current 

 already mentioned. Between Thwaites and Duddon Bridge there 

 are numerous rocJies moutonnees on the slope rising from the W. side 

 of the flat bottom of the Duddon valley, and among them we have 

 the old story repeated, namely, the obliquely-upward glaciation of 

 rocks from and not along the valley. The transverse configuration 

 of the ground shows that (in many instances at least) the glaciation 

 did not result from lateral grinding exerted by a valley-glacier, and 

 it is worthy of remark that the direction of this glaciation approxi- 

 mately corresponds with the striae W. of Green and at Millom 

 quarry. The eastern slope of the upper valley of the Duddon is 

 covered with a succession of gently- swelling knolls (with rocky 

 nuclei) of pinel, and overlying loam, both containing large boulders. 

 In many places there are roches moutonnees, with parallel undula- 

 tions or wide v_^-shaped grooves (as well as minute strise), pointing 

 N.N.E. or nearly in the direction of the valley. But the great 

 wonder of the Duddon valley is the 



Lateral Moraine near Seathwaite. — On walking along the road near 

 Seathwaite Church, in company with the Eev. F. A. Malleson, of 

 Broughton-in-Furness, and Mr. Postlethwaite, a neighbouring squire, 

 I was almost astounded at the appearance presented by what at first 

 looked like a black causeway of large blocks thrown down in haste 

 by a pre-historic race of giants, and I could not believe that the 

 spectacle was natural, until Mr. Postlethwaite assured me that it was 

 so. It runs along the grass-covered (and apparently drift-covered) 

 slope which rises gently from the east side of the valley to the ridge 

 called Walna Scar. There are no rocky scarps above from which 

 the blocks could have tumbled down. They are nearly all quite 

 angular, and are rudely congregated, often piled on one another, 

 within a well-defined zone, a few scores of yards in breadth, and 



