De Long Mountains

De Long Mountains. The De Long Mountains are a subrange of the Brooks Range located in the North Slope Borough of the U.S. state of Alaska. These remote mountains form part of the westernmost extension of the Arctic Cordillera and are characterized by rugged, glaciated peaks and deep valleys. The range is named for George W. De Long, a noted United States Navy officer and Arctic explorer.

Geography and geology

The De Long Mountains are situated west of the Schwatka Mountains and are primarily drained by the Kukpowruk River and the Utukok River, which flow northward into the Chukchi Sea. Geologically, the range is composed of sedimentary rocks, including significant formations of limestone and shale, which were extensively deformed during the Mesozoic era. This deformation is part of the broader Brookian orogeny, a major tectonic event that shaped much of northern Alaska. The landscape features prominent cirques and U-shaped valleys, evidence of past Pleistocene glaciation, similar to other ranges within the Arctic National Wildlife Refuge. Key peaks and passes within the range remain largely unmeasured and unnamed due to the area's extreme remoteness and challenging access.

History and exploration

The mountains were named in honor of George W. De Long, who commanded the ill-fated Jeannette expedition in search of the Open Polar Sea in the late 19th century. Initial mapping of the region was conducted by explorers and surveyors from the United States Geological Survey during the early 20th century, as part of broader efforts to chart Alaskan territories. The area saw increased attention during the petroleum exploration booms of the mid-20th century, with geological parties from companies like Atlantic Richfield Company and the United States Department of the Interior conducting surveys. Despite these forays, the De Long Mountains remain one of the least-visited and most inaccessible regions in North America, with no permanent settlements or significant infrastructure.

Ecology and climate

The region experiences a harsh Arctic climate, with long, severely cold winters and short, cool summers, typical of the Alaska North Slope. Vegetation is primarily tundra, consisting of low-growing plants such as cottongrass, Arctic willow, and various mosses and lichens. This ecosystem supports wildlife adapted to extreme conditions, including populations of the Western Arctic caribou herd, Dall sheep, Arctic fox, and grizzly bear. The rivers and coastal areas are critical habitats for species like the king salmon and provide nesting grounds for migratory birds, including the yellow-billed loon and various sea ducks. The entire area falls within the traditional lands and subsistence hunting grounds of the Iñupiat people.

Natural resources and significance

The De Long Mountains are situated within the National Petroleum Reserve–Alaska, an area managed by the Bureau of Land Management for its potential oil and natural gas resources. While not as prolific as the nearby Prudhoe Bay oil field, the region has been the subject of intermittent lease sales and exploratory drilling, such as those conducted near the Smith Bay area. The range also holds significant paleontological importance, with fossil discoveries from the Cretaceous period providing insights into ancient Arctic ecosystems. Its remote wilderness character contributes to its value for wildlife conservation and scientific research on climate change impacts in the Arctic. The mountains' role as a hydrological divide for north-flowing rivers underscores their importance in the broader Arctic landscape of Alaska.