permafrost

Perennially frozen ground, occurring wherever the temperature remains below 0øC for several years, whether the ground is actually consolidated by ice or not and regardless of the nature of the rock and soil particles of which the earth is composed.

Related terms:

• continuous permafrost zone
• active permafrost
• saturated permafrost
• permafrost island
• dry permafrost
• permafrost table
• fossil permafrost
• passive permafrost
• permafrost line
• relict permafrost