There are two main processes of internal deformation; creep, which forms fold structures, and faulting, which occurs when ice cannot creep fast enough and forms superficial tensional fractures. Basal Sliding Enhanced Basal Creep - Stress concentrations around the upstream side of an obstacle result in locally high strain rates which causes ice to accelerate around the obstacle. The basal ice continually modifies its shape to allow a continued sliding. This process works best when the obstacle is over 1m in size. Regelation - The process allows glacier ice to slide over rough beds by melting and refreezing on the downglacier side.
as discharge decreases the river can only carry finer material. meltwater deposits material when the stream divides, if the velocity of flow decreases, if the channel widens decreasing the pressure, if the stream flows upwards. kames- mounds of sand and gravel. surface streams on glaciers deposit material in crevices. when ice melts debris is left as a pile on the valley floor.
Snow changes properties and is difficult to measure and study in its natural environment. Ice Crystals form when water vapor condenses around and freezes upon a foreign particle such as dust or sea salt. These Ice crystals then form various varieties of snow flakes. Snowflakes can fall in many forms, including ferns, crystals and needles. These snow flakes begin transforming as soon as they hit the ground.
Ablation till can be further subdivided into meltout till and flow till. Meltout till is a direct product of ablation continuing beneath a cover of detritus and flow till consists of debris that has built up on ice and after saturation with melt water becomes so unstable that it flows or slumps into near by hollows.
Here there are obstacles to the flow and friction between sediment and bedrock. It is here that a large influx of meltwater can affect ice sheet dynamics by either increasing basal melting or through lifting of the ice sheet.
There are two distinct types of avalanches: loose avalanches and slab avalanches. While they are structurally different systems, both can be equally troublesome to those recreating in the mountains. Loose, or point-release, avalanches occur on slopes where the snow has simply lost its ability to remain on the slope. This is due to cohesionless snow sloughing off the surface, and picking up more snow as it falls down-slope. As the first particles of snow begin to release on the steeper aspects of the slope, they collide with lower particles, and create a fanned, triangular appearance on the slope.
When this happens it is called a slab avalanche. Other layering characteristic will create other avalanches and hazards, such as ice avalanches and cornices. Whenever traveling in avalanche country it is important to be aware of your environment. Steep gullies and wide plains are perfect paths for avalanches. Ridges and unconformities in the terrain may help to slow down an avalanches speed.
There are many different glacial landforms created by glacial erosion, one of these landforms is U-shaped valleys or glacial troughs. This glacial landform has many distinct characteristics. One of these characteristics is that it has very steep valley sides caused by the glacier as it moves down the valley eroding the sides of the valley by the processes of abrasion and plucking. Abrasion is when the boulders and moraine carried by the glacier rubs and erodes the valley side as it physically moves down the valley. Plucking happens when the water in the glacier freezes inside of the cracks in the individual rocks on the valley side then the water freezes and as the glacier moves the rock is plucked or torn from the valley side producing the steep side to the valley.
The glacier strongly resembles a real mountain, one that has endured a blizzard of phenomenal proportion. Instead of being a brown dirt slope with patches of white snow and ice, it is the opposite. A perfectly white slope pocked with patches of brown. The end of the glacier, which is about as far away as the eye can see, is pressed against the ground, like an unstoppable force working against an unmovable object.
One way is for the snow to develop a crust and then there be more snowfall. Since snow doesn’t bond to the crust it becomes a potential for an avalanche zone. Another way is for surface hoar to develop, or large ice crystal on the snow. This is usually caused by condensation on the snow surface. This will also have poor bonding characteristics, and cause for a potential slide.