Vega locality 3: answers

Ridge-shaped deposition

Appearance

The answer to this question will probably vary greatly from person to person. The most important is to come to the conclusion that it is a coherent, long ridge with a somewhat irregularly shaped surface that winds its way down the valley. Some might also see that the slope from the ridge top towards south is steeper than the north-facing, toward the signpost?

Size

The important thing here is to get an idea of the size, not the exact measurements.  As you can see the ridge is many 100 meters long, from the mountain foot and downward. It is more than 20 m wide at its maximum, and approximately 10 m high.

Grain-size

The grains which are seen on the surface is substantially boulder, but you will certainly find finer material below the surface. You can also see that the grains are angular.

Type

Grain size and shape of the grains suggests that ridge is composed of till. This, along with the ridge form, indicates that it is a marginal moraine formed by a glacier which has been situated within the ridge (figure 3 in the presentation). The reason the slope facing the former glacier is steepest is that the glacier has pulled sediments in front of it as a bulldozer and deposited it as a moraine.

Great-scaled erosional form

As you can see the depression  outside the moraine has a longitudinal form going parallel with the moraine  down-valley. This suggests that it is formed by glacial erosion of a local valley-glacier that started in the front of the summit, the same that formed the moraine.

The moraine was probably formed by a global climatic depression around 12 800 years ago, in Younger Dryas, when the ice-front of the Main Ice Sheet was situated further inland.

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