Bamble is dominated by two types of landscape with completely different geological histories.
In Bamble we find the oldest rocks in the geopark, our bedrock! Up to 1500-million-year-old rocks have given us a fantastic archipelago, with islets and reefs and not to mention the big boulders! In addition, the bedrock has laid the foundation for historically important mining operations. Bamble has a rich mining history that can be traced back to the 16th century. Mainly metals and industrial minerals were mined, some examples include quartz, feldspar, apatite, zinc, lead, iron and nickel. The most well-known mining areas are Tråk, Ødegården's works and Bamble nickel mines.
The bedrock has its origins in two large mountain range formations from, as far as we know, 1500 and 1100 million years ago. Mountains high as the Himalayas slowly eroded and the bedrock is what’s left. With its folds and stripes, the rock testifies to violent forces and high temperatures, several tens of kilometers down under the mountain ranges.
To the east of the municipality, the bedrock tells a completely different story, with much younger rocks that were once the seabed of a tropical sea. The stratified sedimentary rocks, consisting of limestone, sandstone and slate, continue through north through Grenland. When these layers were formed, Norway was part of a tropical ocean full of life, somewhere south of the equator, about 500 million years ago. In Høgenhei, the well-known landmark south of Grenlandsbrua, it is easy to see the different layers in the old seabed.