Bolshezemelskaya tundra number 2
The patterns of their development and the formation of surface microforms were identified. Among these forms, not only specific, but also extremely complex were such formations as polygonal surfaces of permafrost soils, permafrost mounds, folded from the surface by layers of cracked peat, closed thermokarst depressions, funnels, saucer-like depressions, and solifluction terraces, ramparts, earthen rivers. The fact is that in the polar (and high-altitude) regions, which are characterized by the development of long-term seasonal and permafrost, some regularities of the development of the relief have been established.
All of these complex physical phenomena cause restructuring and the creation of unique, microform reliefs, characteristic only of certain natural zones of the continents. The polygonal ("poly" —multiple, "ton" - angle) surface of the tundra is found in places where parts of the tundra are not disturbed by other physical phenomena, and slow accumulation of loose sediments takes place. Here, repeated rhythms of freezing and thawing for tens and hundreds of years create a spotty surface structure. Homogeneous or complex (a combination of fine-grained, coarse sand, small stone inclusions) the soil cracks during severe frosts. The surface is divided into 5-6-sided polygons, which gradually merge, forming large cracks bounding polygons with a diameter of up to several meters. Cracks sometimes reach 0.7 - 1.0 m depth. Gradually, the cracks are filled with stones, coarse sand, and a small homogeneous mass of soil accumulates in the center of the polygon. The cracks are better drained, protected from strong winds, and tundra vegetation grows along them, which even more strongly emphasizes the dense bare surface of the soil of the spots - polygons. Often, during blizzards, fine spots of soil are blown away along with snow. Using the polygonal surface of the tundra is very difficult.
Detailed studies of each specific area of dense fine-earth spots, cracks filled with loose sediments, thawing layer, inflow or runoff of melt and rainwater, etc. are required. In overmoistened tundra depressions, small mounds covered with cracked peat layers are usually found. They are formed as a result of very complex hydrogeological processes in areas of permafrost. A strong and prolonged freezing of wetted soils, including peat, leads to an uneven distribution in their depth of both water and temperature. In the layers of soil and peat, lenses of thickened frozen inclusions slowly form. This leads to the formation of hillocks, in which the frozen cores increase with time, and they stand out noticeably among the lowered wetted tundra. Such wetlands with tundra areas are very difficult and difficult to master. On a surface with an inclination angle of more than 3-5, in areas of permafrost, there is a runoff of soil oversaturated with water. This phenomenon is called solifluction. Due to the reduction of friction and the simultaneous increase in weight, the loose soil filled with water under the influence of gravity flows down along the surface of permafrost strata. During the season, the ground flows from several decimeters to tens of meters. As a result of solifluction, solifluction terraces, ramparts, earthen rivers, and loops are formed on the slopes. All large relief forms acquire soft outlines, smooth slopes with characteristic gradations. Slow-flowing soil as a result of complex freezing-thawing processes is experiencing sorting of detrital material. On the slopes of the formed stripes composed of coarse-grained (gravelly) material and strip of silty loam. Sometimes they stretch parallel to each other for several hundred meters and even for 3-5 km, creating the illusion of continuous streams of earthen rivers.
On the ground, such “streams” are relatively difficult to distinguish, and from the height and on aerial photographs of the earth’s surface they are well recognized. They are usually impossible to confuse with other landforms. In the practice of developing the northern territories there are many annoying examples when such conditions for the development of soils caused great damage during construction. Buildings erected on active solifluction bands in the spring need measures to preserve them. By the beginning of summer and summer, almost all designs can “flow” along with the ground. Buildings can practically be destroyed, as the wetted soil can not be strengthened. The study of the patterns of development of solifluction relief makes it possible to realistically assess the difficulties of natural conditions in the Bolshezemelskaya tundra. new zealand online casinos
MicroGiving is an online fundraising website that lets you create your own fundraiser. Raise money online easily with a personal fundraising page