While being repeatedly covered by glaciers during the Quaternary (last 2.5 million years), Fennoscandia has seen little effect on any changes in its topography from glacial erosion. Denudation during this time is geographically highly variable but averages tens of meters.[23] The southern coast of Finland, Åland and the Stockholm archipelago were subject to considerable glacial erosion in the form of scraping during the Quaternary.[24] The Quaternary ice ages resulted in the glacier's erosion of irregularly distributed weak rock, weathered rock mantles, and loose materials. When the ice masses retreated, eroded depressions turned into the many lakes seen now in Finland and Sweden.[25][26] Fractures in the bedrock were particularly affected by weathering and erosion, leaving as result straight sea and lake inlets.[27]