Page 32 - (DK Eyewitness) Travel Guide 2017 - Alaska

30  INTRODUCING ALASK A

Alaska’s Glaciers

Much of Alaska’s spectacular landscape has been
shaped by 5,000 major and countless minor glaciers that
scraped downhill from icefields in the coastal mountains,
gouging out steep-sided valleys. As glaciers melted,
valleys that were below sea level were filled by seawater
to create long, narrow fjords. Although glaciers continue
to reshape the land scape, most of these rivers of ice –
the earth’s largest reservoir of freshwater – are currently
receding, and scientific research suggests that human-
caused warming of the planet may be the primary reason.
Crevasses develop when stresses
on the flowing ice cause large
cracks in glaciers. The largest
crevasses are found on steep
sections of rapidly flowing ice.

Outlet Glaciers, such as Mendenhall Glacier near Juneau, spill
down steeply from icefields, creating ravines that serve as outlets
for the icefield. They often flow into lakes created by the glacier’s
terminal moraine, a ridge of debris at the foot of the glacier.

Glacial Changes
Lateral moraines are
As glaciers flow downhill, friction against strips of ground rock on
the rock melts the bottom ice, forming the edges of glaciers.
a “slide” so the glacier can surge ahead.
Increasing air temperatures can cause
melting at glacier faces, but can also
cause surging, as higher temperatures
mean more snowfall, and therefore, pres­ Bergy bits are large
sure, on parent icefields. Tidewater gla­ chunks of glacier ice
or small ice bergs,
ciers flowing into warming seas tend to rising up to 13 ft
recede due to higher water temperatures. (4 m) out of the water.
Alaska’s Prominent Glaciers
Key Canada
Alaska Alaska
1 Aialik (see p107)
2 Exit (see p103)
3 Portage (see p85)
4 Eklutna (see p83)
5 Matanuska (see p184) Canada
6 Columbia (see p119)
7 Worthington (see p121)
8 Childs (see p123)
9 Bering (see p41)
0 Kennicott (see p193) Gulf of Alaska
q Malaspina (see p155)
w Hubbard (see p31)
e Margerie (see p146) 0 km 200
r Mendenhall (see p145) Pacific Ocean
0 miles 200

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