Geologic Time

Precambrian Era: The Precambrian era represents the vast majority of Earth's history, extending from the formation of the Earth around 4.6 billion years ago to approximately 541 million years ago. The Baltic Shield, also known as the Precambrian Shield, is a large area of ancient igneous and metamorphic rocks that form the foundation of much of Norway. These rocks date back to the Precambrian era and provide evidence of early Earth history, including the formation of continental crust and the assembly of the supercontinent Rodinia.

Paleozoic Era: This era spanned from around 541 to 252 million years ago. During the early Paleozoic, Norway was part of the continent Baltica, situated close to the equator. Sedimentary rocks from this time can be found in the Oslo Rift and other areas. The later part of the Paleozoic witnessed the formation of the Caledonian Mountains, also known as the Scandinavian Mountains, which stretch across much of Norway and Sweden. These mountains were formed during the Caledonian orogeny, a major mountain-building event that occurred during the Silurian and Devonian periods. The rocks in this region include a mix of sedimentary, igneous, and metamorphic rocks, which were folded and faulted as a result of tectonic collisions. 

Mesozoic Era: The Mesozoic era lasted from approximately 252 to 66 million years ago. Norway experienced uplift and erosion during this time, leading to the development of new sedimentary basins. Fossils from marine life and dinosaurs have been discovered in some Mesozoic rocks. The Oslo Rift is a significant geologic feature in southeastern Norway, characterized by a series of faults and sedimentary basins formed during the breakup of the supercontinent Pangaea in the Mesozoic era. The rocks in this region include sandstones, shales, and volcanic deposits that preserve evidence of ancient environments and tectonic activity.

Cenozoic Era: The Cenozoic era began around 66 million years ago and continues to the present day. During this era, Norway experienced significant glacial activity and the formation of fjords, which are characteristic features of the country's landscape. The most recent glacial period, known as the Pleistocene, occurred around 2.6 million to 11,700 years ago. During the Pleistocene Ice Age, large ice sheets covered much of Norway, shaping the rugged mountainous terrain and carving deep, narrow valleys. As the glaciers retreated, they left behind moraines, lakes, and U-shaped valleys that contribute to Norway's distinctive landscape today.