Beaches and Glaciers and Waterfalls, OH MY!
9:22 am- We arrive at our first stop, an overlook just before Hveragerði. Our Southeast view overlooks the coastal plain, off shore in the distance the Vestmannaeyjar Islands are visible. The islands formed some 11ka from underwater eruptions that were able to produce enough lava to cause the islands to breach the surface. The Islands town, Heimaey gained national attention when a basaltic lava flow destroyed half of the town in 1973. As our view shifts East, active volcanism in the area is apparent. Dozens of geothermal vents are seen gassing in the distance.
Beyond the vents lie a thick layer of clouds obstructing the distant view of Hekla, 75km away. Though not in sight, her presence is known. We start our descent to the coastal plain.
Hekla is located between the East and West volcanic zones and at the junction of fracture zones. The volcano has both a rift and a crater. Hekla is the third most active of Iceland’s volcanos and has erupted 18 times since settlement. Folklore refers to the volcano as the “Gateway to Hell”. Hekla likely got her namesake due to her unpredictable eruption characteristics as well as the explosive eruption that took place 1120ka. The eruption of 1120 was an explosive one which produced 2.5km^2 of Rhyolitic tephra. Hekla does not fall under typical classification for volcanos, she is closest to the big two, but is neither a stratovolcano or shield volcano. Hekla is the 4th type of volcano because her eruption characters are unique. Hekla eruptions happen in stages. Stage one is an explosive, Plinian eruption that produces tephra similar what a stratovolcano would. This stage lasts hours at a time. Following the Plinian stage, fissures open and Hekla erupts effusively. High-density andesite lava spreads as it is expelled from the fissures. The effusive stage of the eruption can last days, months or longer.
10:10 am- We are driving through the coastal plain headed towards “Black Beach” when we cross the Pjorsa river, the largest river in Iceland. The Pjorsa spans 200km and is fed by the glaciers of the highlands.
11:20 am- With the thought of highland glaciers in our minds, we notice the landscape to our North begins to change. Basaltic lava flows appear higher and higher as we continue East. Glaciers topping the mountains in the distance are visible. There are narrow meltwater streams and that foss flow between rocks, some take the path of small glacial valleys, others spring out of the cliffside seeming to favor the path of least resistance between contacts of lava flows. Large 2-15m diameter boulders at the base of the hills are plentiful. These boulders were shifted free due to freeze thaw movement and weathering. The characteristic wrinkle pattern on sod covered hillside is evident. Streams contribute by erode away the footing of these boulders, breaking them loose. They roll until they hit something or the ground levels enough to stop them. Farmers seem to have a good understanding of rock and roll and utilize every inch of land, right to the danger zone.
11:55 am- At this point we have spotted many glacial features such as circs and glacial valleys, each one larger than the previous.
1:35 pm- We stumbled off of the bus and onto the sand of “black beach”, easily mistakable with others due to its color. The black sand results from the erosion of basalt lava from Iceland’s rivers in addition to that of the cliffside visible to our East and West, specs of white calcareous marine animals are in the basalt.
We move to the base of a wave cut cliff to look at a perfect example of columnar basalt. The basalt columns to our right stand vertical and are about .5m wide and have 5-7 sides
Left of the vertical columns are smaller sized columns that appear more random and wavy. These columns appear to radiate out wards, between the two groups of columns there is a sea cave.
Another sea cave is seen 100m down the coast. The roof of this sea cave is also made up of radiating columnar basalt, the columns appear to radiate opposite to the arc of the sea cave and form an apex above the center of the cave.
Looking along the coast there are many examples of marine landforms and evidence of previous sea levels. There are three marine terraces in the distance. West is a headland with a large sea arc between us and the headland is a possible wave cut platform. Extending from the headland are three stacks , the closest on is highest and the most angular, the ones further out appear more rounded. As we are walking back to the bus we see a paraglider land next to us, I fanaticize about it for a second, then we drive off and hike to our lunch spot.
1:50pm- Our lunch spot is on top of a series of moraine ridges at the base of a large glacial valley. The glacier visible to our North must have extended out and beyond where we sit, but that’s obvious, we are on a moraine. I think the moraine we are sitting on is a middle moraine. It is hard to tell because water discharged from the glacier above looks to have broken the once perfect moraine ridges and we have to use our imagination to connect them. On the edges of the valleys there are Kane terraces. Kane terraces allow us to determine the height of the glacier that formed them. Dating the terraces to get a timescale of when the glacier was there can also be done.
3:10- We start hiking up the Solheimajokull glacier’s valley toward the glaciers tongue. Striations on a fragment of volcanic breccia sparks our interest. This rock, with its parallel carvings and irregular pieces of volcanic rock all cemented together within a matrix of tephra tells us a story. A story with explosive origins. Of a section of basalt lava shattered from is from its place by glacier or eruption. Whatever the case, the piece of basalt, its shape differing from its pillowy beginning is now an angular fragment laying among many others. Not long after being reduced to a fragment (geologically speaking), a sheet of tephra encompasses is. The tephra and basalt become lithified in place and form into a bed of volcanic breccia.
As the breccia sits, a glacier tongue retreats and advances, incising and slowly carving its way down the highlands. A valley in its wake. The tongue of the glacier extends, and the valley carved by ice grows near. The bed of breccia is passed by the glacier which now scrapes along it. The glacier retreats, striations- parallel scars on the face of the breccia, serve as evidence of the glaciers extent. Succumbing to the forces of weathering and freeze/thaw, a fragment of breccia breaks from its bed at the upper portion of the now glacial valley. The fragment tumbles down the valley and stops near the valley floor where it is now an obstacle for the hundreds of people who pass it daily, its story of which, they do not know.
5:10 pm- We take a pit stop at Skogafoss and climb to the top! We also fill our bottles with fresh, clear glacial water.
6:20 pm- We make our last stop of the day at the magnificent Seljalandsfoss and take some time to explore behind its falls.
