1: Fossils

Fossils from the Ice Age

The ice sheet of the last glacial period, the Weichselian glaciation, destroyed most of the fossil remains in Finland, but some fossils, such as the bones and teeth of mammoths and other prehistoric animals, have been found in our sedimentary strata. Ancient trilobite fossils have also been discovered in the Åland Islands.

Tree fossils

Most discovered fossils originate from araucaria or palm trees. Petrified trees consist of several different, colourful minerals. The most common ones are jasper, opal and translucent chalcedony, adorned with other minerals, such as rock crystal and pyrite.

The largest specimens have been found in Argentina: they are around 80 metres tall with three-metre-thick trunks. Some that are nearly as large have been discovered in Arizona, USA, and Thailand.

Coral fossils

Coral fossils have been found in few locations, and the largest deposit is in Tampa Bay, Florida, USA. The insides of fossilised corals have generally turned into agates in a variety of colours, also called agatised coral.

Flint

Finland does not have flint deposits, but due to its diverse range of uses, it has been imported here as early as the Stone Age from Russia and Central Europe, used as ballast in sailing ships, and it can therefore still be found in Finnish harbours. In the past, pieces of flintstone were used in tinderboxes to spark a fire.

Trilobites

Trilobites were one of the most successful marine life forms of the Palaeozoic era (540–250 million years ago). Nearly 20,000 species of trilobites have been identified from fossils. Their length varied from one millimetre to 75 centimetres. Generally, only the chitinous exoskeleton has been preserved in the fossils, without legs or antennae.

Dendrites

The manganese forms black and brown patterns inside the rock. The iron, on the other hand, forms brown patterns, also common on rock surfaces. Dendrites are often found on limestone, but they appear on many different rock types. Dendrites can form either through crystallisation or precipitation.

Dendrite formations can be very diverse. Their appearance is affected by different factors, including the minerals in them, surrounding rock type, as well as environmental circumstances, such as pressure and temperature. Dendrites are often used as ornaments, and they can also be made into jewellery.