Terii’s Cycling Babble

Gave It My All! » 01-31 b Geology Feature 1 Pano

Geological Feature


According to the sign, this knob of rock is called the ‘Alnö Intrusion’ and is famous world wide. It is unique within the Swedish bedrock. About 560 million years ago these various types of rocks including one sort called ‘alnöites’ were forced up (intruded) from the depths of the earth through the roots of a volcano. Erosion has scoured away 500 meters of the top layers leaving part of the ‘root’ exposed. Within an area of about 20 square kilometers (at least a fair chunk of Alnö island I’m guessing) are minerals and rocks that occur nowhere else in Sweden.

There was a detailed description of where on the rock face you can see what kinds of minerals/rock inclusions, but without being able to see them, it’s pretty much pointless to type it.

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