Boulder trail – wyborgite

All erratic boulders you can find in Estonia have been brought here by the last big glacial ice during the ice age – so about 10,000 years ago. When the glacial ice covering Estonia began to melt, meltwater accumulated in front of its edge. Finally, a huge glacial lake formed from the continuously accumulating meltwater. It was called the Baltic Ice Lake, and it was the predecessor of the current Baltic Sea.

The rock you are currently studying is wyborgite. It is a special type of rapakivi granite, which was discovered for the first time in south-eastern Finland. Like others, this rock was brought here by the huge continental glacier thousands of years ago. This rock type stands out for its red or pink rounded feldspar crystals that are surrounded by greenish rims of calcium feldspar, or plagioclase. These speckled rocks are named after the Finnish Viiburi Rapakivi pluton.