The exact age of coming into existence of amber is unknown. Nevertheless, it is certain that amber came into being thanks to resin from trees covering the area of Scandinavian countries and the northern part of the Baltic Sea which used to be a land in that time. An amber-giving forest existed in that place even in the Paleogene era. A bit warmer climate than today let different kinds of trees grow in that forest. Coniferous trees, broadleaved trees, palms and sago cycads, or just sago palms, could grow together. We do not know the name of a species of a tree which fossil resin comes from. It is likely that was a coniferous tree that derives from a pine family.
The reason of such profuse secreting of tree resin is also unknown. One of the most probable hypotheses is connected with an increased volcanic activity which took place at the end of the Paleocene era and at the beginning of the Eocene era, 58 - 48 million years ago. According to this theory, formulated by a Polish botanist – professor Hanna Czeczot, sticky volcanic ash which settled on the branches of the trees could have been the reason of such profuse secreting of their resin.
The resin, which was produced by trees, was flowing out of their injured places. It was dribbling out of the broken branches, flowing down their bark and then it was gathering under the bark, filling up cracks in trunks and roots. Up to now there has been some bark and tree fiber retained in many lumps of amber.
The resin, which had dribbled out, remained unset for some time. That was a sticky trap which tempted mostly insects, scarcely for example scorpions or small reptiles. It also happened that some pieces of plants, drops of water and air bubbles were sunk in the resin. Foreign bodies trapped inside the lumps of amber are called inclusions. They give us a unique possibility of seeing the world from millions of years ago in almost unchanged form.
In the amber-giving forest the trees were falling down due to disasters, illnesses or they were just dead because of their age. The hardened resin was still in their trunks which covered by a few layers of bedding started to decompose very slowly. For some time the resin, which the Baltic amber was about to come into existence from, stayed in a shallow layer of residue, in the place where it had come into being.
In the late Eocene era, 37-34 million years ago, this residue was slowly scoured out as a result of erosional activity of rivers. The northern part of area which is now the Baltic Sea might have been a vast valley the main axis of which was a hypothetical river called Eridan by professor Barbara Kosmowska-Ceranowicz, a Polish amber researcher.
The waters of the Eridan carried amber with crushed rocks towards the south and they left that deposit of material in the form of river delta in a shallow bay of The Eocene Sea. That deposit was called “blue soil” because of glauconite which was typical of sea residue that was dominative among crushed rocks and the colour of it is characteristic - green and blue.charakterystycznej, zielono-niebieskiej barwie osady te nazwano „niebieską ziemią”.
For the following millions of years, up to the beginning of the Pleistocene era, the layer of amber-bearing soil remained covered with other layers of residue. About one million years ago there was a glacial age, the first one of the series of a few glacial periods. The Scandinavian ice sheet was moving forward and backward and in the same time it was carrying away some pieces of amber-bearing residue and it was scattering it all over today`s Poland. A big part of this residue has been untouched. Placed along the southern coastline of the Baltic Sea has become the main source of Baltic amber.
