Journey From The Bridge Between Continents to the Beach!
We begin our journey on Wednesday August 15th at the Bridge Between Continents. The Bridge Between continents is a rift zone where you can walk from the Eurasian plate over to the North American plate due to its location over the mid-Atlantic ridge.
In this area we can see evidence of the 1220 eruption. vesicular basalt is abundant here. There are two types of basaltic lava flows, the pahoehoe and the Aa. Pahoehoe lava tends to be runny and fluid heavy. It tends to form in a rope-like structure. This type occurs due to high temperature magma from the low part of the mantle. The Pahoehoe flow has an average temperature of 1300° C, which is more than 10x the boiling point of water. Aa lava flows slower than Pahoehoe lava and tends to be very angular chunks. We see many examples of tumuli, which are characteristic of areas with Pahoehoe lava. They tend to be dome shaped formations with a bread crust appearance due to the bulging of lava to the surface which cracks the rock above it. As we walked further into the rift we began to see the structure of a shield volcano. We can also see a clear example of a graben in the rift zone.
There used to be a large population of birch in this area until it was covered by the lava from the 1220 eruption. Now there is not a lot of fauna due to the composition of the soil. As an area of mostly basalt, there is not enough nutrients in the soil to facilitate plant life. A majority of the basalt here has an aphanitic crystal size which after oxidation turns it into clay. If the soil were made of Andesite or Rhyolite than plant life would be able to thrive. As we continue to walk we see young fissures in the rift zone. The soil here is also weathered basalt but it also contains white specks. These white specks are due to the wind blowing seashells over from the beach. Abundant amounts of ropey Pahoehoe lava flow evidence is present. The rift zone begins to get filled up by dunes as we get closer to the beach. 63°51’59” N 22°40’56”W we see a massive lava tube. Continuing along there are more tumuli structures and large dunes. As we start to see the beach come into view we can notice many coastal geomorphological gestures like a bay mouth bar, a lagoon, and headlands. Also visible is Fire island which was created due to uplift of the Mid-Atlantic Ridge. Just before we arrive at the beach, we spot columnar tumuli structures and some noticeable honeycomb weathering from water and wind.
Also visible are an abundant amount of lava bombs. 63°51’50” N 22°41’59”W we finally arrive at the beach. Grass covered dunes can be seen with Arctic Fox trails along them. Driftwood sticking out of the top of one of the dunes shows just how high the waves used to be. This beach is also home to numerous seagulls.
We trek for an hour and arrive at 63°50’45” N 22°40’54”W, the location of a splatter cone volcano. There was a massive crater and many large scoria chunks.
That concluded our trip for the day.