Free Cold by Bill Streever Page B

marking the world’s timeline with glacial and interglacial periods. The ice sheets expanded during
     glacials and retreated during interglacials. The Pleistocene Ice Age is only now appearing to peter out. The last glacial
     ended ten thousand years ago. Today’s interglacial leaves us with nothing more than Antarctica, scattered mountain glaciers,
     and the remnant ice sheet of Greenland. The Pleistocene Ice Age gave the world woolly mammoths, the ice-carved valleys of
     Alaska, and the beauty of Scotland. But for all this, the Pleistocene Ice Age was only one of at least four major ice ages
     in the world’s timeline. And it was no more than a chilly breeze compared to the ice age of seven hundred million years ago,
     when the entire planet may have been more or less frozen, a godforsaken snowball hurtling through space.

    It is September tenth and sixty-eight degrees on the lower slopes of Ben Nevis, Scotland’s highest peak. Scotland’s reputation
     for mountains comes from their abundance, not their height. Ben Nevis is a mere 4,409 feet tall, a bump trying to become a
     hill and calling itself a mountain. Nevertheless, the tourist information office issues dire warnings. Hikers should have
     warm clothes. They should be prepared to overnight in cold, wet conditions. The mountain creates its own weather. Snow can
     come at any time. Fog can cloak the route without warning. Hikers should have adequate food. They should have an Ordnance
     Survey topographical map and a compass, and they should know how to use both. In short, they should take the hike seriously.
    My companion and I walk the lower slopes in T-shirts and shorts. Between us, we have two scones left over from breakfast.
     We have the map from our walking guide to Scotland, a small, unreadable sketch that shows a zigzagged switchback trail leading
     toward a summit. My compass is in Alaska. Her compass is in Holland. In short, we have no choice but to climb the mountain.
    It is an upward slog, steady and constant. We round a bend, and wind slaps us head-on. We are both sweating, and the cold
     wind is a comfort. We pick up the pace.
    Scotland is a landscape formed by ice. To drive up from London is to drive into glaciated terrain. South and west of the extent
     of glaciation, it is flat and neatly cultivated. Then it becomes the rolling hills of glacial moraine. Here the glaciers coming
     from the north slowed, retreated, advanced again, finally stopped and pulled back. With each hesitation, millions of pounds
     of crushed rock and dirt were dumped, leaving moraines behind to form the rolling hills. Farther north, small steep mounds
     called drumlins pock scattered valleys. Drumlins formed when hard rock under the glacier slowed down its forward movement.
     Tripped by the obstruction, the glacier dumped part of its load of rock and dirt. Most of it piled up just upstream of the
     obstruction — up-glacier, toward the source of the creeping snow and ice — forming a blunt slope, while the downstream tail
     tapered to ground level. Drumlins in Scotland often occur in bunches that are sometimes called “baskets of eggs.” And that
     is what they look like: baskets of earthen eggs on valley floors. And with the drumlins, scores of erratics — boulders carried
     by glaciers — pepper the valley floors and the shallower slopes of the mountains. The erratics — odd shapes, some small enough
     to be lifted by one man and others the size of a van — stand or lie on their sides. Sheep wander around them, grazing, chewing
     stupidly in the midst of grandeur.
    Farther north, in the Scottish Highlands, the mountains and valleys have been shaped by glaciers. It could almost be Alaska.
     The ridges are often knife-edged, sharpened by glacial erosion into what some call arêtes. Arêtes form when glaciers freeze
     around rocks. Glacial water finds its way into cracks and crevices, refreezes, expands, shatters the rocks, and then sweeps
     the broken mess downhill. A