164 J. C. WARD ON THE GLACIAL ORIGIN OP THE 



head of each the various beds of the Upper Silurian are shifted, 

 and markedly so in the case of Coniston, further down the lakes 

 the strata would appear to cross unbroken. 



Y. Summary. 



1. During the period of maximum glaciation, the various glaciers 

 of this southern part of the district, as of the northern, were more 

 or less confluent, and most of the lower elevations were buried under 

 a continuous sheet of ice, which often moved diagonally across the 

 lower parts of ridges separating valley from valley. 



2. The occurrence of some glacial scratches crossing water-shed- 

 ding lines at high elevations, in a general east and west direction, 

 and frequently in passes or cols, seems to point, perhaps somewhat 

 doubtfully, to the agency of floating ice, and to support the suppo- 

 sition that the submergence reached to more than 2000 feet*, and 

 may have extended to but little short of 2500 feet. 



3. The existing moraines are the products of the second land- 

 glaciation ; the glaciers of this period seem never to have become 

 confluent, as in the former, but occupied the heads of all the prin- 

 cipal valleys. 



4. Several of the larger lakes, such as Wastwater and Winder r 

 mere, are rock-basins running down beneath the present sea-level. 



5. These roek-basins, however, are but shallow grooves at the 

 bottom of the valleys in which they occur; and their depth is small 

 as compared with the thickness of the ice which moved over these 

 spots. Hence it seems most probable that the theory of glacial 

 erosion is the true one, and the points of evidence brought forward 

 in the case of Wastwater are strongly confirmatory. 



6. Mountain-tarns appear to be due, sometimes wholly to glacial 

 "erosion, sometimes to this combined with a moraine dam, and occa- 

 sionally to the pounding back of water by moraines alone, or moraine- 

 like mounds, at the foot of snow-slopes. 



EXPLANATION OF PLATE VII. 



A. Horizontal sections to illustrate the form of the Wastwater valley, the depth 

 of the lake, the height of the mountains, and the thickness of the ice, together 

 with a plan of Wastwater,— depths being given in feet. All on a true scale of 

 1 inch to 1 mile. 



Fig. 1. Longitudinal section through Wastwater, with outlines of the mountains 

 occurring on the north side of the valley. 



2. Transverse section through Wastdale Head, between Kirk Fell and 



Scafell Pikes. 



3. Section from Pillar Mountain to Scafell, through the junction of Mose- 



dale and the head of Wastdale. 



4. Transverse section from Yewbarrow to the N.E. end of the Screes' 



Mountain. 



5. Transverse section from the mouth of Over Peck to the N.E. end of the 



Screes Mountain. 



* See "Summary" in " Glaciation of the Northern Part of the Lake-Dis- 

 trict," Quart. Journ. Geol. Soc. vol. xxix. p. 440. 



