At The End of the Earth: Iceland

At the end of the earth, Iceland is one of the most beautiful and haunting places on Earth.

Ancient Lava Field Covered with Moss on the Southern Coast
The climate of Iceland's coast is subpolar oceanic. The warm North Atlantic Current ensures generally higher annual temperatures than in most places of similar latitude in the world. Constant coastal mist produce four inch thick blankets on aa lava fields. Every precarious footstep seems an insult to this rich botanical carpet.
Braided River, Skeidararsandur
Late in the evening of September 30, 1996, seismometers detected the beginning of an eruption under the glacier. One of the volcanoes had previously collapsed and formed a caldera named Grimsvotn, in which a subglacial lake had been accumulated. Late on the first of October, the day after the eruption started, the surface of the ice over the caldera had risen ten to fifteen meters. The next day, the eruption broke through the surface of the ice, emitting an ash cloud ten kilometers high. The volcano quieted on the thirteenth, but the ice continued to melt and overflow the Grimsvotn lake. More than three cubic kilometers of ice melted, but little was emitted through normal runoff points. Since an ice dam and the caldera itself held the melt back, the jokulhlaup would not occur until November, or at least one month later.
Braided River, Skeidararsandur, Iceland
Braided River and the Ring Road, Skeidararsandur, Iceland The November 1996 jökulhlaup that burst from the Vatnajökull ice cap onto Skeidarársandur was the highest-magnitude flood ever measured on the largest active glacial outwash plain (sandur). Centimeter-scale elevation transects, measured from repeat-pass airborne laser altimetry missions flown in 1996 (pre-flood), 1997, and 2001, show that sediment deposition exceeded erosion across the central Skeidarársandur and established an average net elevation gain of +22 cm for the event. Net elevation gains of +29 and +24 cm occurred in braided channels of the Gígjukvísl and Skeidará rivers, respectively. Nearly half of these gains, however, were removed within 4 years, and the two rivers contrast strongly in style of erosional/depositional impact and subsequent recovery. In the Gígjukvísl, the 1996 jökulhlaup caused massive sediment deposition (up to ∼12 m) near the ice margin and intense "mega-forming" of braided channels and bars downstream. Post-jökulhlaup recovery (1997-2001) was characterized by rapid erosion (-0.5 m) of ice-proximal sediments and their transport to downstream reaches, and eradication of the mega-forms. In contrast, the Skeidará displays minimal post-jökulhlaup sediment erosion in its upstream reaches and little change in braided channel relief. This contrast between river systems is attributed to the presence of a previously studied ∼2-km wide ice-marginal trench, caused by glacier retreat and lowering, which contained flows of the Gígjukvísl but not the Skeidará prior to dispersal onto the outwash plain. Rapid removal of jökulhlaup deposits from this trench suggests that in terms of long-term evolution of the sandur, such features only delay downstream migration of jökulhlaup-derived sediment. These results, therefore, suggest that the net geomorphic impact of jökulhlaups on surface relief of Skeidarársandur, while profound in the short term, may be eradicated within years to decades.
Braided River, Skeidararsandur, Iceland
Braided River and the Ring Road, Skeidararsandur, Iceland The November 1996 jökulhlaup that burst from the Vatnajökull ice cap onto Skeidarársandur was the highest-magnitude flood ever measured on the largest active glacial outwash plain (sandur). Centimeter-scale elevation transects, measured from repeat-pass airborne laser altimetry missions flown in 1996 (pre-flood), 1997, and 2001, show that sediment deposition exceeded erosion across the central Skeidarársandur and established an average net elevation gain of +22 cm for the event. Net elevation gains of +29 and +24 cm occurred in braided channels of the Gígjukvísl and Skeidará rivers, respectively. Nearly half of these gains, however, were removed within 4 years, and the two rivers contrast strongly in style of erosional/depositional impact and subsequent recovery. In the Gígjukvísl, the 1996 jökulhlaup caused massive sediment deposition (up to ∼12 m) near the ice margin and intense "mega-forming" of braided channels and bars downstream. Post-jökulhlaup recovery (1997-2001) was characterized by rapid erosion (-0.5 m) of ice-proximal sediments and their transport to downstream reaches, and eradication of the mega-forms. In contrast, the Skeidará displays minimal post-jökulhlaup sediment erosion in its upstream reaches and little change in braided channel relief. This contrast between river systems is attributed to the presence of a previously studied ∼2-km wide ice-marginal trench, caused by glacier retreat and lowering, which contained flows of the Gígjukvísl but not the Skeidará prior to dispersal onto the outwash plain. Rapid removal of jökulhlaup deposits from this trench suggests that in terms of long-term evolution of the sandur, such features only delay downstream migration of jökulhlaup-derived sediment. These results, therefore, suggest that the net geomorphic impact of jökulhlaups on surface relief of Skeidarársandur, while profound in the short term, may be eradicated within years to decades.