36 A SUMMER IN GREENLAND 
causing portions of the berg to burst with a loud 
report. 
A doubtful throne is ice on summer seas. 
On a still night the booming of breaking icebergs 
is often the only sound that disturbs the silence. 
If the ice is not too far away, the effect of the loss 
of a part of the mass as the detached pieces fall 
with a roar into the water is seen in the heaving 
of the iceberg which slowly and majestically rises 
and sinks, and may turn completely over, eventu- 
ally coming to rest in a new position and with an 
entirely different aspect. The words of the Ancient 
Mariner, 
The ice did split with a thunder-fit... 
It cracked and growl’d, and roar’d and howl’d, 
aptly describe the rending of a large berg. The 
smooth grooves and ridges on the side of the ice- 
berg above the water-level seen in Fig. 13 were 
formed by wave-action and indicate the shifting 
of the equilibrium of the ice since they were pro- 
duced. The upper part of the berg consists of 
angular pieces of ice embedded in a dirty matrix, 
a fairly common type of structure which may have 
its origin in the débris filling a large crevasse in 
the parent glacier. 
There are few more superb sights in nature than 
a sheet of water with floating icebergs. The scene 
over Umanak Fjord (Fig. 14), with some of the 
highest mountains in Greenland on its northern 
and eastern shores, comes tomy memory. It wasa 
perfect night: a clear sky, and the sun not far above 
