A landscape in motion
The Mackenzie River Delta is the second-largest in the Arctic, a sprawling 13,000-square-kilometer labyrinth of channels and wetlands. Beneath this vast plain lies a foundation of permafrost—permanently frozen ground—that is in some places over 100 meters thick. This frozen earth is not static; it is a dynamic landscape shaped by a process called thermokarst. As pockets of ice-rich permafrost thaw, the ground surface collapses and subsides, creating a pockmarked terrain of hummocks and water-filled depressions.
This process gives rise to the delta's most numerous feature: its lakes. There are tens of thousands of them, constantly forming, shifting, and disappearing. Some lakes can drain with astonishing speed when a thawing ice wedge opens a new channel, an event known as catastrophic drainage. The landscape is also sculpted by retrogressive thaw slumps, a type of landslide that occurs when thawing ground-ice on a slope turns the soil into a muddy slurry. These slumps can retreat several meters in a single summer, dumping huge amounts of sediment and dissolved minerals into adjacent lakes and altering their water chemistry.