Luokkiniemi diabase vein

The ancient continent started to crack. Molten rock erupted from the cracks. Part of the magma crystallised in the cracks to diabase. You can recognise diabase as a dark-coloured vein in a bedrock outcrop, for example, in Luokkiniemi on Kuosto island. Gradually, the cracks opened to become valleys and sea bays, in which sand and gravel were deposited. The deposits crystallised to quartzites and conglomerates most easily found in rocky grounds in Utajärvi.