Permafrost is ground that stays frozen year-round.
Typical profile of permafrost areas in interior Alaska
Photo by CRREL
This type of permafrost is almost all ice. It forms inside permafrost through the ground cracking annually and filling with water.
Photo by Matt Bray
This type of permafrost is filled with almost microscopic ice disks. It may look like mostly dirt, but it commonly up to 75% ice.
All of Alaska and circumpolar north, scientists are monitoring air temperature, permafrost temperature, wind, rain fall, snow fall, and a variety of other measurements. We use this data to monitor changes related to climate change.
Scientists drill borehole to collect permafrost samples for geology, engineering, and climate change studies.
Smaller boreholes are drilled to install temperature measuring equipment into the permafrost. They use the data to monitor change related to climate change or human disturbance (roads, buildings,etc.)
The frost probe is also known as a thaw probe or tile probe. The metal probe can find push through thawed soil but not the ice-cemented soil of permafrost. Scientists use this in the fall to measure changes in the amount of summer time thaw on the ground surface.
Black Spruce Forests
The black spruce forests with a moss ground floor is what commonly grows on permafrost in the interior of Alaska. It is part of the larger forest type called the Boreal Forest or Tiaga.
15,000 year old Paleosol
15,000 years ago, near the end of the Last Ice Age, this was the ground surface in this area. Falling windblown dirt slowly covered the land and buried this vegetation mat of mostly grasses.
30,000 year old Paleosol
This was the ground surface 30,000 years ago. Like the 15,000 year old paleosol, this land was slowly buried by wind-blown dirt. This process preserved plant remains, seeds, pollen, and insects.
This type of permafrost is ice-bonded gravel. It has very little ice and generally safe to build on.
Bedrock can be permafrost too, because permafrost is temperature based not based on whether it has ice.
Bones and plant remains are often buried in permafrost by falling into sinkholes or being buried by landslides.
Permafrost can be difficult to build on because it can be mostly ice, and when it thaws it turns into soupy mud. Houses not properly built can start sinking into the permafrost has heat from the house thaws it.
Water running on the surface from a small stream, heavy rains, or large snowmelt can start melting and eroding ice wedges. This will create a large pit in the ground that will continue to grow with each rain storm.
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