Ice wedges can resemble a giant quilt when seen from the air and form only where permafrost is found. During very cold weather, solidly frozen ground can shrink and crack. When snow melts in spring, water runs into the cracks and freezes, which causes the cracks to grow. Most cracks are preserved beneath the ground surface. If the ground above ice wedges is disturbed by vehicle traffic or warmer conditions, however, the ground above the cracks melts and reveals the ice wedges. NPS scientists are monitoring Alaska's permafrost by mapping landforms like pingos, wedges, and thaw slumps. Learn more on the NPS Arctic Monitoring Network's permafrost webpage: www.nps.gov/im/arcn/index.htm