Moraine

Morrena.

Morrenas around the Iceed Lake (2709 m), just below the Musala peak (2925 m), in the Rila Mountain, Bulgaria.

Morrena.

Garda Lake Morrena.

A moraine or moraine is an elongated ridge or mantle of till (non-stratified glacial material) that is deposited near a glacier. There are several types of moraines, depending on their relationship with the glacier:

• Background moraine: located under the ice, in contact with the bed.
• lateral moraine: the derubs are located on the shores of the glacier bed.
• central morrena: formed by the union of lateral morrenas in the confluence of two glaciers in the same valley.
• front or terminal moraine: are derrubios deposits in the glacier melting zone.
• ablation moraine: are those that have been sedimented on the glacier bed. They present heterogeneous materials, but the most characteristic is the presence of large scattered blocks along the way, called erratic blocks.

Sediment deposited directly by a glacier is also called a moraine. The glacier descends from considerable heights and drags the materials it finds on its way.

Training

Outer moraines are formed by the fragments that fall on the glacier ice from the slopes. The internal moraines are composed of materials transported within the ice mass from the outside that have fallen into the sedimentation zone, where they have been covered by snow and have sunk with it. The bottom moraine is the layer of boulders left behind after a continuous retreat of the ice. The material of a moraine is generally a mass of sediments subject to subsequent modifications and destruction by the action of the waters originating from the melting ice. When two glaciers meet, two lateral moraines join to form a median moraine. There is talk of terminal moraine when the rock fragments are deposited while the ice neither advances nor retreats. A thrust moraine is the result of an advance of the ice through the moraine that causes the sediments to recede and fold, forming a structure due to tectonic deformation.