Evolutionary processes of Greenland glaciers

The glacier macroforms, in particular, the configuration of the ice sheet itself, are determined by the entire set of glacier life processes. Even when considering the schematic profile of the ice sheet, it is easy to imagine that a violation of each of these functions will affect the configuration of the ice sheet. There is a direct link between the shape of the glacier's surface and the intensity of accumulation, ablation, and the speed of ice movement, as well as these functions themselves are interdependent.

Throughout the entire period of existence of the Greenland Glacier, the intensity of its life processes has changed several times. During the period of maximum, the glacier's power increased, which was caused by a sharp increase in the neuron accumulation. The balance was achieved due to a sharp increase in the production of icebergs, since the edges of the glacier reached a wide front towards the ocean. In the future, climate warming should have led to a violation of the ratio between the flow and power of the glacier. With an increase in the firn line, the ablation of the lower parts of the ice sheet increased, which should have caused a temporary increase in the curvature of the surface of the cover and, consequently, increased ice outflow to the periphery of the glacier. The rebalancing could be achieved, firstly, by an isostatic uplift of the underlying surface of the glacier itself and, secondly, by a reduction in the production of icebergs, since the edges of the glacier retreated from the ocean for a considerable distance.

In the process of reducing glaciation, the marginal part of the glacier underwent a rather complicated evolution. The decrease in ice thickness has led here to a gradual disintegration of the cover into separate arrays. This process could be especially vigorous in those places where, due to the strong vertical dismemberment of the glacier bed, its surface had a wavy relief. Dome-shaped bulges that overlapped the elevated parts of the bed, separated from the ice cap and preserved in the form of isolated glaciers such as ice caps. Along with them in the depressions remained the fields of motionless dead ice, located between the more active glaciers of the hills. The most common types of glaciers in the coastal parts of the island are ice caps and glaciers of the elevations. In general, these are inactive glaciers, often with a negative balance.

The Danish expedition examined one of these glaciers in the southern part of the Peary Land and found that the average annual accumulation on its surface is about 115 mm and the ablation is 160 mm. Its surface has a slightly convex shape inherited from a more powerful cover. Ablation at the bottom of the ice cap is largely compensated for by the influx of ice from the central part of the glacier, so that its edges almost never recede. Therefore, the glacier dies off so far mainly due to the reduction of its thickness in the middle part and gradual flattening. However, not all of these glaciers have a negative balance. In northwestern Greenland, many of the glaciers of this type exhibit marked activity. Vast glaciers descend from the extensive caps that cover Prudhoe Earth, which move at speeds of up to a meter per day.

Fields of dead ice are quite often found both on elevations (glaciers of elevations are an intermediate stage between glaciers-caps and dead ice), and on plains at the edge of the cover glacier. The fields of dead ice form, for example, a part of the Ile-de-France island off the northeastern coast of the island, as well as the surface of many areas of King Frederick VIII's Land.
It is necessary to note the peculiarity in the spread of glaciers of hills and ice caps: these glaciers are now preserved only in areas that were subject to glacial cover (they are not present, for example, in the northern part of the Peary Land). This circumstance confirms their relict nature and genetic connection with the surface glaciation of the island.

In the southern part of the island, glaciers of this type are relatively rare. This is due in part to the high position of the snow line, but mainly because the general climatic situation here contributes to the formation of more active glaciers, of course, under favorable orographic conditions. After the retreat of the cover glacier, alpine-type mountain glaciers arose here. Many of them, for example, on the Land of King Christian IX, formed extensive foothill glaciers, on one side adjacent to the cover glacier, and on the other side, descending to the ocean. Especially favorable conditions for the development of glaciers of this type are in the area of ​​Angmagsalika, where the snow line descends to 250 m in height. do it CVV shops in