siirtolohkareita

Siirtolohkareita, also known as glacial erratics, are rocks that have been transported and deposited by glaciers, often far from their original geological source. These massive stones, sometimes weighing many tons, are a common feature in landscapes shaped by past ice ages. As glaciers advanced, they picked up rocks from the bedrock and carried them along, either embedded within the ice or as sediment at the glacier's base. When the ice melted, these rocks were left behind in their new locations, often appearing incongruous with the surrounding local geology.

The presence of siirtolohkareita provides valuable evidence for the extent and direction of past glacial movements. Geologists can study the composition of these erratics and compare them to the bedrock of different regions to determine their origin. This helps in reconstructing glacial pathways and understanding the history of ice sheet formation and retreat. They are found in many parts of the world, particularly in areas that were covered by large ice sheets during the Pleistocene epoch, such as North America, Europe, and Scandinavia. Their size and the distance they have traveled can vary significantly, with some erratics being relatively small pebbles and others enormous boulders.