Korttia - Glacial Potholes

At Korttia, 26km/16mi from Porvoo on the Lahti road (No. 55), can be found a group of some 20 potholes up to 10m/33ft deep, scoured out of the granite by the grinding action of pebbles swirled round by melt-water during the retreat of the glaciers in the last ice age, some 10,000 years ago.