What you have to know is that Shetland, 600 million years ago, was placed in a vast desert continent somewhere near the Equator!
The island of Yell can boast some of the oldest rocks in Shetland. You will observe them on this place for exemple: gneiss (a banded or foliated rock), quartzite (is a hard metamorphic rock which was originally sandstone)... Aged between 2.8 billion and 1 billion years old, many have been subject to repeated metamorphism, (is the solid-state recrystallization of pre-existing rocks due to changes: pressure and temperature ) which can be seen to spectacular effect along the west coast.
The island of Yell is composed of Moine rocks. Originally laid down 1000 million years ago as thick layers of sand and mud in the sea on the edge of American continent, they were metamorphosed when Scandinavia, Europe and America collided.
Around you, you will see ice-created sea lochs (or small fjord.).These were created when the ice age ended and the ice began to melt (2.6 million years ago), it carved the rocks deeper into the sea.!
Exhibits celebrating the beauty and diversity of Yell’s rocks can be found at the Old Haa in Burravoe.
Questions :
1. What type of rock very typical can you find here? Look at the pictures below to answer and take pleasure in learning something about geology.
If you see picture 1, you are standing in front of rocks called basalt, a common extrusive (Extrusive refers to the mode of igneous (fire)volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava )volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It is, in fact, the most common rock in the Earth's crust.
If you see picture 2, you are standing in front of rocks called gneiss. Gneisses tend to be banded on a large scale with layers and streaks of darker and lighter colored gneiss. Gneiss is usually of the same composition as granite (hard igneous rock).
If you see picture 3, you are standing in front of two types of stones: The darker trachyt, lava that was cooled down. The other is the red, orange one - the ashes of the volcano that was forming the stone. The two of them were piled over another - forming the stripes.
2. Please, take a picture of you of your GPS on the top and put it on your log, if you want to do so!
Send your answer via our e-mail and we’ll give you permission to log, and especially, take advantage of this interesting place!
More informations ?
http://en.wikipedia.org/wiki/Moine_Supergroup
http://gsabulletin.gsapubs.org/content/97/6/754.abstract
http://en.wikipedia.org/wiki/Peat_bog
Shetland museum and archives (Lerwick)
Interpretive map of Shetland geology (Professor Derek Flinn, cartography by Kay Lancaster
http://en.wikipedia.org/wiki/List_of_Shetland_islands
http://www.shetlandtimes.co.uk/2010/05/21/the-nature-of-shetland
http://www.shetlandtimes.co.uk/2010/05/21/a-journey-through-shetlands-geology
Take time to go to Sands of Breckon, it is well worth .(N 60°43.563 W 01°02.114)
pricklyangelduo
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