Under the Nature Conservation Act, individual natural formations such as trees, copses or erratic boulders can be protected as natural monuments. The basis for such protection can be its rarity, importance to the landscape, scientific value, beauty, etc. The damaging or spoiling of a protected natural monument is forbidden.
Natural monuments in Helsinki
Helsinki has 31 natural monuments. Most of these are trees or copses that are special in some way, but they also include potholes, rocky gorges and erratic boulders. The Pihlajamäki potholes, one of which is the largest in Finland, can be regarded as a national natural monument. Geological research has shown that they were created by the rotation of the melt water of the ice age before last.