Amid the fierce gales of the Atlantic, the nation of Iceland clings to the mid-Atlantic Ridge like lichen on a warm rock. This is an island of extreme contrasts: high peaks drop sharply to sea level, glaciers grow on the slopes of active volcanoes, and coastal deserts run out to the ocean.
These contrasts have resulted in a unique geophysical system, and it's because of this system that Kelly and I have travelled here to 63°N latitude. The question of focus is the impact of fine glacial dust on the atmosphere: we're here to collect samples of this sediment, which Kelly will study in the lab at Leeds. The dust of interest is formed at the ice/bedrock interface of glaciers: rocks are carried along with the motion of the glacier; the grinding of these rocks against underlying bedrock produces very fine rock dust. This dust is flushed out from the glacier during seasonal melting or in the catastrophic floods unique to glaciated volcanoes. Braided rivers carry this sediment towards the ocean and deposit some of it across broad glacial outwash plains. These plains are barren, nearly featureless and, with the exception of the active river channel, dry. This fine glacial dust is readily carried aloft in the strong winds that rip across the plains. Could these abundant, fine particles impact cloud formation? This paper discusses these plains as a source of mineral dust to the atmosphere.
We took a train through the rural countryside south of Leeds, caught a ride through the London Tube, and boarded a flight to Keflavik, Iceland. The flight route returned us back north over nearly the length of the United Kingdom, and we had an great cloud-free view of the dark River Thames crossed by lit bridges in central London. We arrived into Keflavik very late last night. In the early gray light of the cloudy far-north dawn, we walked out through frozen dew-covered grass and took a quick pre-breakfast dip in the thermal springs that rose in the backyard of our hostel. We got an early start and drove all day through eerie fog, strong winds, and some respectable rain.
The gray, white-capping ocean, the sheer mossy cliffs, and the constant fog make for a mysterious landscape. The features here are very large--the southern coast is made from tall peaks, broad plains and the wide-open sea--and the sight distance in the fog was about 1-3 kilometers, with a low cloud deck. In some direction, the landscape is always disappearing into the fog. In the lees of ridges and under the protection of tall cliffs, some very old stone structures still stand. Along the southern coast, proud, happy humans have painted their houses and churches with bright red roofs. There is a good bit of agricultural land, mostly dedicated to grazing and hay.
Our scientific targets are the enormous outwash plains of the Southern Coast, but we took advantage of some other sampling opportunities as we crossed the island. At the first small outwash plain, we collected the contingency sample, as the Apollo astronauts did moments after stepping onto the moon. Later, we collected a series of samples on the braided banks of the Mulakvisl River, including a volume of water that we'll allow to settle as a test. At both sites, we were buffeted by strong winds and rain, and we're now drying out our gear in our hotel room. Between the rivers and the rain, we'll be wet for the next few days. Tonight we're sleeping at a settlement near Myrdalssandur, the first of the great outwash plains along our route.
In the photo below, look for the old stone structure built into the face of a cave. Click to enlarge.
