Earthcache Amazing Faroese Geology – Rockwall in Gróturd
The Faroe Islands were formed by volcanic eruptions 60 to 55 million years ago. At this time this area had rain forest an a subtropical climate. Long fissures volcanoes were immediately west of the Faroe Islands. During a volcanic eruption lava flowes from long fissures. The lava flows buried the rainforests under thick layers of basalt. These volcanic eruptions formed the Faroe Islands. Every eruption formed a horizontal basalt layer which characterizes the Faroese mountains.
Rainforest on the Faroe Islands
During a break in the volcanic activity, vegetation returned to the naked basaltic plains. Vegetation, including equisetum and trees grew fast in the warm climate. Soon the rainforest was blooming with giant Metasequoia trees and Gingko. The cycle between volcanic eruptions to rain forest continued for some million years.
Forest fire at Groturd
There was a rainforest at this side at Groturd 55 million years ago. The volcanic eruption began as so many times before. Large quantities of lava flows erupted from the fissures and covered the land area. When the hot lava flow which cools fast, the tree shape and even parts of the trees can be presented. Fossil imprints of leaves and plants can also been seen in the reddish sedimentary layers (tuff layers).
Burned Rain Forest in Groturd
You look at an incident, which happened in Groturd many million years ago. We see elongated holes in the solid rock. These are fro tree trunks which burned up that day 55 million years ago when the lava flow hit the rain forest. All there is left the empty mould of the trunks.
Ropy lava
On the solid rock you can see something that looks like soft wrinkles. This is the surface of the hot lava flows as it cooled. This type of surface is called ropy lava and pahoehoe lava.
The wave breakers at Groturd can be fierce. The forces are so violent that the solid rock erodes and changes fast. Sometimes you have to perserve and look a bit around to find the tree mould and rop
I met a geologist at this side. She explained the structure, gave additional information and showed me an empty tree mould of a tree. See picture below.
To log this earthcache.
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Take a look at the picture “profile at Groturd”, when you reached the coordinates. Describe the structure/form (hard, rough, crumbly) and the colour of the with 1 - 3 marked areas in the profile. Estimate the thickness of each layer. For area 3 take the ground level above sea level where are you standing.
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In area 2 you will find different colours in different layers. What is the reason for these different colours.
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Look at the coastal cliff, you will find a lot of big rocks which had fallen down. What do you think is the reason for.
You can imediately log this earthcache. I will contact you, if the answers will not fit.
Please watch out for loose rock in the coastal cliff