Skaftafellsjökull

Skaftafell sits inside Vatnajökull National Park, on a strip of land where the ice cap’s outlet glaciers meet lowland once farmed for centuries before the park absorbed it. The area gives a rare vantage point in Iceland, a place where an ice cap, an active volcano buried beneath it, and an outwash plain shaped by that combination are all visible within a short walk of each other.

A glacier’s edge can appear to retreat even while the ice behind it keeps moving forward. The position of a terminus is the net result of two processes working against each other: forward flow, driven by gravity and the slow deformation of ice under its own weight, and ablation, the loss of ice to melting and calving at the surface. When melting at the snout outpaces the arrival of new ice from up-glacier, the front edge draws back, not because the glacier has stopped, but because it is losing mass faster than it can replace it there. Further back, in the thick core of the ice tongue, the glacier continues to advance the entire time. Skaftafellsjökull, an outlet glacier fed by the southern edge of Vatnajökull, shows this at its crumbling, debris streaked snout.

Markers along the trail show where the ice edge stood in earlier decades. The glacier reached its farthest point around 1890, close enough that it once nearly met the ground the visitor centre now occupies, and it has drawn back most of the time since. Today the snout sits a little over a mile up the valley from where we started, and the walk out to it crosses ground the ice held and then abandoned.

The trail out to the glacier front and back runs 3.7 kilometers, and took us about an hour and a half on flat gravel with almost no elevation gain. The first stretch runs through birch scrub, stunted and wind bent, mixed with smaller plants low enough to stay out of the wind. This kind of vegetation is a recent arrival in geological terms, colonizing ground the ice only released within the last century and a half. The plants thin as the path nears the older moraine ground, giving way to bare gravel and rock as the ice comes into view.

The sky stayed clear the entire walk, open enough to see the full line of peaks along the park’s edge, including Hvannadalshnúkur, at 6,922 feet the highest point in Iceland. The peak sits on the northwest rim of Öræfajökull, a subglacial stratovolcano, the largest active volcano in the country and one of its most dangerous, despite being buried almost entirely under ice. Its last major eruption, in 1362, buried the surrounding district, then called Litla-Hérað, under ash and meltwater and depopulated it; the name Öræfi, meaning wasteland or land without harbor, dates from that event.

The glacier front sits behind a series of moraine ridges, ground and pushed into place by past advances, and in front of the current ice edge lies a shallow proglacial lake scattered with small icebergs calved off the face. These lakes are themselves a product of retreat: as a glacier thins and pulls back, meltwater collects in the basin its own weight scooped out, and the ice front, now floating at the margin, calves more readily into the water. Along the moraine we passed three separate depressions holding standing water, kettle holes. These form when a block of ice breaks away during a retreat and is buried under glacial sediment; the buried ice melts on its own slower timeline, and as it does the ground above it subsides, leaving a hollow that fills with water once the ice beneath is gone.