During the fieldwork we found numerous so called "ice wedge casts". This one was by far the largest and indicates that the mean annual temperature was about -8 degrees Celsius when the ice wedge was formed.

Ice wedges are formed in very cold climates when the soil is frozen and shrinks, creating these cracks. In summer, when the upper layer of the soil is thawing, sand or clay fills the cracks. This process may go on year after year, making the crack wider and deeper. When the climate warms up, the ice wedge remains visible in a cross-section.