Gea Norvegica Geopark
Kongshavn
Bamble’s Geological History
Bamble’s landscape – exciting geology through millions of years
The municipality of Bamble has a long and exciting geological prehistory – a full 1,500 million years long! There are traces of many different events in the bedrock here, from the basement rocks in the south and west, which were once part of mighty mountain ranges, through tropical seas to volcanoes and ice ages.
At Kongshavn, between the center of Langesund and the Fjordline ferry terminal, this long story is told along a timeline. The boulders are examples of the geology in the Bamble area, and on the signs you can read more about the long journey this area has experienced.
The Timeline in Kongshavn – A Brief Overview
Ribbon gneiss: The bedrock west of Bamble consists of ancient basement rocks. These are the oldest rocks, formed in the Earth’s earliest times – the Precambrian. This type is called ribbon gneiss, recognizable by its light and dark “bands.”
Granitic gneiss: Granitic gneiss is also found in the basement rock area west in Bamble. Its origin was different – before the gneiss was transformed, it was probably granite, which is why it is called granitic gneiss.
Knollekalk (nodular limestone): In Langesund and surrounding areas, you find limestone rocks formed on the bottom of a tropical sea, from the Ordovician geological period.
Porsgrunn marble: Porsgrunn marble is not found in the bedrock of Bamble, but with its many fossils, it provides a unique insight into the fauna that existed in the tropical sea covering the land more than 400 million years ago.
Larvikite: The youngest rocks in the area were formed in the Permian, about 300 million years ago. These originated from large volcanoes on the east side of the Langesund fjord. Deep within these volcanoes, Norway’s national rock, larvikite, was formed.
Loose deposits: Scattered around Bamble, you can find stones that don’t seem to belong. These come from the end of the last ice age and are pieces of rock that glaciers and rivers transported from various places in Eastern Norway.
Pebbles of different origins represent the youngest part of our history!