STRAND – The treasures right in front of you

Granite

Coarse-grained, crackled red granite rolls softly like the sea waves of the outer skerries of Åland and gives our roads their pink hue. The rock is also called rapakivi, and it is the very foundation of Åland. Radioactive substances in the minerals work like little clocks, and that is how we know it is over 1,585 million years old. Granite can also be white or black.

Porphyry

The beach stones that move on the colour scale between grey and black are often porphyry. The hard groundmass consists of rapidly solidified lava or ash that has rained down onto the earth. Over the millions of years, quartz, feldspar and hornblende have found their way into the dense structure as hexagonal crystals.

Sandstone

The pale, single-coloured stones on the beach – light grey, yellow and sometimes pink – are sandstone. Water, ice and wind erode different rocks into sand, which is then pressed and cemented together by natural cement. In sandstone, plant parts, shell remains and traces of similar animals can be incorporated as fossils, a greeting from things that lived millions of years ago.

Diabase

Dark or grey-speckled diabase pushes up out of the earth’s crust as magma and fills the cracks in older rock. Diabase contains large amounts of iron and is therefore hard and very heavy; one cubic metre weighs about three tonnes. Our ancestors used diabase to make sturdy tools.

Gneiss

The pinkish-red colour makes gneiss very similar to granite, but on closer inspection the clear bands and veins in parallel layers show that it is gneiss. When the stone has been shaped into small beads it is really tricky to tell the difference.