Active Layer at the Soil Surface
The arctic soil is so cold that the ground beneath the tundra surface remains frozen all year. This permanently frozen ground is called permafrost. Each summer, when the sun warms the tundra surface, the top few inches of soil thaw. This melted part is called the active layer. Plant roots grow within the active layer, and insects burrow here.
Page Photo Credits – All photos courtesy of USFWS unless otherwise noted.
Last Updated: Jan 08, 2014