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moraines. When several glaciers united, some of their lateral moraines 
became confluent and formed cez/va/ moraines upon the surface of the 
compound glacier. The ice, ever moving on, at last reached a point 
where the melting power of the sun’s heat equalled the forward move- 
ment, and here the vast quantities of stony material carried along in 
the ice were thrown off and formed a great semi-circular mound called a 
terminal moraine. 
As the ice was pressed down the valley, it rounded, smoothed, and 
scratched the rocks, by the aid of stones imprisoned between it and 
the rocky sides and bed. Oftentimes, sinking in height, it left 
blocks perched in strange-looking positions, into which they could not 
have fallen. 
Where the ice was squeezed through a narrow gorge, its velocity was 
increased and its power of rocky abrasion likewise. Altogether, 
glaciers not only brought down vast quantities of rocky material from 
higher to lower levels, but they also deepened and abraded the valleys 
through which they flowed, producing greater effect at certain points, 
where the pressure of the ice was greatest, or the rocks were softest, than 
at others. The marks and effects of glacier action were perfectly dis- 
tinctive, unlike those produced by any other natural agent. 
When glaciers terminated in the sea, their ends broke off and formed 
icebergs, which floated away with the moraine material upon them, and 
scattered it over the sea-bed in melting. 
Among the Cumbrian mountains the signs of glacier action at a 
recent period were everywhere plainly visible. Rocks were rounded, 
smoothed, and striated ; huge blocks lay perched in strange positions ; 
many an upland valley was filled with old terminal moraines. 
The sequence of events during the so-called Glacial Period was 
probably much as follows :— 
1. Glaciers, small at first, gradually increased in size as the 
climate became more severe, and kept pushing before them or partly 
overriding their first-formed moraines. 
2. The separate glaciers became united into a more or less con- 
tinuous sheet, clothing the mountainous country in one uniform icy 
mantle. 
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