Pingo
Introduction
A Pingo, also known as a hydrolaccolith or a bulgunniakh, is a geological feature, specifically a type of periglacial landform, that is found in the Arctic and subarctic regions of the world. These formations are essentially hills with a core of ice. The term "pingo" originates from the Inuvialuit word for "small hill". Pingos are a fascinating subject of study in the field of periglacial geomorphology due to their unique formation process and the insights they provide into the periglacial environment.
Formation
Pingos are formed in areas with permafrost, where the ground is frozen for two or more consecutive years. The formation of a pingo begins with the development of a permafrost layer, which can occur in a variety of ways. One common method is through the freezing of a subterranean water source, such as a lake or pond. As the water freezes, it expands, pushing the overlying soil upwards and creating a mound. This process is known as hydrostatic uplift.
The growth of a pingo can take anywhere from a few decades to several centuries, depending on the specific conditions of the environment. The size of a pingo can vary greatly, with heights ranging from a few meters to over 70 meters and diameters from a few meters to over 2 kilometers. The largest known pingo, located in the Tuktoyaktuk Peninsula of Canada, stands at a height of 70 meters and has a diameter of 2 kilometers.
Types of Pingos
There are two main types of pingos: closed-system pingos and open-system pingos.
Closed-system pingos, also known as hydrostatic pingos, form in areas where there is a confined source of water, such as a drained lake or pond. The water in the ground freezes and expands, pushing the overlying soil upwards to form a mound. These types of pingos are typically found in flat, inland areas and are the most common type of pingo.
Open-system pingos, also known as hydraulic pingos, form in areas where there is a continuous supply of ground water. The water is drawn up into the permafrost layer by capillary action and freezes, causing the ground to bulge upwards. These types of pingos are typically found in areas with steep slopes and are less common than closed-system pingos.
Ecological Significance
Pingos play a significant role in the Arctic and subarctic ecosystems. They serve as elevated points in the otherwise flat tundra landscape, providing habitats for a variety of plant and animal species. The unique microclimates created by pingos can support a diverse range of flora and fauna, contributing to the overall biodiversity of the region.
In addition, pingos can serve as indicators of climate change. The formation and degradation of pingos are closely tied to the temperature of the environment. As such, changes in the number and size of pingos can provide valuable information about changes in the permafrost and the overall climate of the region.