Mackenzie Delta: Canada’s Principal Arctic Delta
| Autor: | C. R. Burn |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Delta
geography Ground freezing geography.geographical_feature_category 010504 meteorology & atmospheric sciences Wetland 010502 geochemistry & geophysics Permafrost 01 natural sciences Alluvial plain Arctic Submarine pipeline Physical geography Geology Tree line 0105 earth and related environmental sciences |
| Zdroj: | World Geomorphological Landscapes ISBN: 9783319445939 |
| Popis: | Mackenzie Delta, in Canada’s western arctic, is North America’s largest arctic delta. For over half the year, the rivers and lakes of this vast alluvial plain are ice covered. Permafrost is ubiquitous in the delta and the surrounding landscape. The tree line traverses the delta, separating closed-canopy white spruce forests in southern parts from low shrub tundra and sedge wetlands at the Beaufort Sea coast. The extension of the delta northwards into the ocean is the net result of 128 Mt of sediment brought annually to the delta by Mackenzie and Peel rivers, of which about two-thirds is deposited offshore. The permafrost of the uplands adjacent to the delta is ice rich, with numerous tabular bodies of almost pure ice that formed when the ground originally froze. Throughout the region, the terrain surface is criss-crossed by networks of ice-wedge polygons, initiated by water freezing in cracks opened by ground contraction during winter cooling. A large number of pingos—ice-cored, conical hills up to 50 m high—have developed in the sandy sediments of drained lakes in the area. These features grow as permafrost aggrades in saturated lake sediments. Continual uplift of these little hills demonstrates the enormous forces that can be generated by ground freezing. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|