more. It occurred to me now that a great part of my mindless indifference to my
surroundings earlier on was simply that I didn't know where I was, couldn't know where I
was. Now at last I could take my bearings, perceive my future, feel as if I was somehow
in touch with a changing and knowable landscape.
And so I walked five thoroughly agreeable miles up Kittatinny to Sunfish Pond, a very
comely forty-one-acre pond surrounded by woods. Along the way, I encountered just two
other people--both day hikers--and I thought again what a stretch it is to suggest that the
Appalachian Trail is too crowded. Something like thirty million people live within two
hours' drive of the Water Gap--New York was just seventy miles to the east, Philadelphia
a little bit more to the south--and it was a flawless summer's day, yet the whole of this
majestic woods belonged to just three of us. For northbound hikers Sunfish Pond is
something of a glorious novelty, since nowhere south of here will you find a body of water
on a mountaintop. It is in fact the first glacial feature northbound hikers come across.
During the last ice age, this was about as far as the ice sheets got. The farthest advance
in New Jersey was about ten miles south of the Water Gap, though even here, where the
climate would let it go no farther, it was still at least 2,000 feet thick.
Imagine it--a wall of ice nearly half a mile high, and beyond it for tens of thousands of
square miles nothing but more ice, broken only by the peaks of a very few of the loftiest
mountains. What a sight that must have been. And here is a thing that most of us fail to
appreciate: we are still in an ice age, only now we experience it for just part of the year.
Snow and ice and cold are not really typical features of earth. Taking the long view,
Antarctica is actually a jungle. (It's just having a chilly spell.) At the very peak of the last
ice age 20,000 years ago, 30 percent of the earth was under ice. Today 10 percent still is.
There have been at least a dozen ice ages in the last two million years, each lasting about
100,000 years. The most recent intrusion, called the Wisconsinian ice sheet, spread down
from the polar regions over much of Europe and North America, growing to depths of up
to two miles and advancing at a rate of up to 400 feet a year. As it soaked up the earth's
free water, sea levels fell by 450 feet. Then, about 10,000 years ago, not abruptly exactly
but near enough, it began to melt back. No one knows why. What it left in its wake was a
landscape utterly transformed. It dumped Long Island, Cape Cod, Nantucket, and most of
Martha's Vineyard where previously there had just been sea, and it gouged out the Great
Lakes, Hudson Bay, and little Sunfish Pond, among much else. Every foot of the landscape
from here on north would be scored and scarred with reminders of glaciation-- scattered
boulders called erratics, drumlins, eskers, high tarns, cirques. I was entering a new world.
No one knows much of anything about the earth's many ice ages--why they came, why
they stopped, when they may return. One interesting theory, given our present-day
concerns with global warming, is that the ice ages were caused not by falling
temperatures but by warming ones. Warm weather would increase precipitation, which
would increase cloud cover, which would lead to less snow melt at higher elevations. You
don't need a great deal of bad weather to get an ice age. As Gwen Schultz notes in Ice
Age Lost, "It is not necessarily the amount of snow that causes ice sheets, but the fact
that snow, however little, lasts." In terms of precipitation, she observes, Antarctica "is the
driest large area on Earth, drier overall than any large desert."
Here's another interesting thought. If glaciers started reforming, they have a great deal
more water now to draw on--Hudson Bay, the Great Lakes, the hundreds of thousands of
sean pound
(Sean Pound)
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