Parr Y. Suor. i. §1.] PLEISTOCENE. 898 
_ yalleys in the Scottish Highlands. It is believed that the mass of ice 
descending from some of the loftier snowfields of the time was so great 
as to accumulate in front of lateral valleys, and to so choke them up 
as to cause the water to accumulate in them and flow out in an oppo- 
site direction by the col at the head. In these natural reservoirs the 
level at which the water stood for a time was marked by a horizontal 
ledge or platform due partly to erosion of the hill-side and partly to 
the arrest of the descending debris when it entered the water. 
Eyery group of mountains nourished its own glaciers; even small 
islands, such as Arran and Hoy in Scotland, had their snowfields, 
whence glaciers crept down into the valleys and shed their moraines. 
It would appear indeed that some of the northern glaciers of Scotland 
continued to reach the sea-level even when the land had risen to 
within 50 feet or less of its present elevation. On the east side of 
Sutherlandshire the moraines descend to the 50-feet raised beach ; 
on the west side of the same county they come down still lower. The 
higher mountains of Hurope still show the descendants of these later 
elaciers, but the ice has retreated from the lower elevations. In the 
Vosges the glaciers have long disappeared, but their moraines re- 
main still fresh. In Wales, Cumberland, and the southern uplands and 
Highlands of Scotland, where moraines, perched blocks, and roches 
moutonnées attest the abundance and persistence of the last glaciers, 
it is possible to trace the stages of the gradual retreat of the ice 
_ towards its parent snow-fields, in the crescent-shaped moraine mounds 
that lie one behind another until they finally die out about the head 
of the valley, near what must have been the edge of the snow-field. 
The uprise of the land in Scandinavia and Britain took place 
interruptedly. During its progress it was marked by long pauses 
when the level remained unchanged, when the waves and floating 
ice cut ledges along the sea-margin, and when sand and gravel were 
accumulated below high-water mark in sheltered parts of the coast- 
line. ‘These platforms of erosion and deposit (raised beaches) form 
conspicuous features at successive heights above the present level of 
the sea (p. 277). The coast of Scotland is fringed by a succes- 
sion of them. ‘hose below the level of 100 feet above the sea are 
often remarkably fresh. The 100-feet terrace forms a wide plateau 
in the estuary of the Forth, and the 50-feet terrace is as conspicuous 
in that of the Clyde. In Scandinavia, especially in the northern 
parts of Norway, the successive pauses in the last uprise of the 
land are impressively revealed by long lines of terraces which wind 
around the hill-slopes that encircle the fjords (p. 279). 
The records of the closing ages of the long and varied Glacial 
Period merge insensibly into those of later geological times. It is 
obvious that besides the effect of a general change of climate operating 
over the whole of the northern hemisphere, we must remember the 
infiuence which the natural features of different countries had upon 
the climate. From the plains the ice and snow would retire sooner 
than from the hills. In fact, we may regard some parts of Europe as 
