what are crevasses and where do they form?
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A crevasse is a deep, wedge-shaped opening in a moving mass of ice called a glacier. Crevasses usually form in the top 50 meters (160 feet) of a glacier, where the ice is brittle.
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An icefall is a portion of certain glaciers characterized by rapid flow and a chaotic crevassed surface. The term icefall is formed by analogy with the word waterfall, a similar, but much higher speed, phenomenon.
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In the creation of fold mountains, Earth's crust itself is warped into folded forms. Fold mountains are often associated with continental crust. They are created at convergent plate boundaries, sometimes called continental collision zones or compression zones.
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Tuff Rings A "tuff ring" is a small volcanic cone of low relief that surrounds a shallow crater. These craters, known as maars, are formed by explosions caused by hot magma coming in contact with cold groundwater. The explosion blasts fragments of bedrock, tephra, and ash from the crater.
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Fold mountains are often associated with continental crust. They are created at convergent plate boundaries, sometimes called continental collision zones or compression zones. Convergent plate boundaries are sites of collisions, where tectonic plates crash into each other.
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Sometimes, limestone erodes and forms caves beneath the earth. As the ceilings of these caves collapse, canyons form. The Yorkshire Dales, an area in northern England, is a collection of river valleys and canyons created by limestone cave collapses. Canyons are also formed by tectonic activity.
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They usually have steep, sloping sides and sharp or rounded ridges, and a high point, called a peak or summit. Most geologists classify a mountain as a landform that rises at least 1,000 feet (300 meters) or more above its surrounding area. A mountain range is a series or chain of mountains that are close together.
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Fiords are glacier-cut valleys that flooded as sea level rose in post-glacial times. A cirque represents an erosional feature formed in what was an important accumulation zone for snow and ice at the upstream head of a glacier.
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Weathering and erosion can create caves, arches, stacks and stumps along a headland. Caves occur when waves force their way into cracks in the cliff face. ... The stack will be attacked at the base in the same way that a wave-cut notch is formed. This weakens the structure and it will eventually collapse to form a stump.
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Coronae (Latin: “garlands” or “crowns”) are landforms that apparently owe their origin to the effects of hot, buoyant blobs of material, known from terrestrial geology as diapirs, that originate deep beneath the surface of Venus. Coronae evolve through several stages.
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These mountains form when faults or cracks in the earth's crust force some materials or blocks of rock up and others down. Instead of the earth folding over, the earth's crust fractures (pulls apart). It breaks up into blocks or chunks.
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It is a form of deep foundation which are constructed above ground level, then sunk to the required level by excavating or dredging material from within the caisson. Caissons (also sometimes called “piers”) are created by auguring a deep hole into the ground, and then filling it with concrete.
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paper defines hollows as"sub-kilometer scale, shallow, flat-floored, steep-sided rimless depressions typically surrounded by bright deposits and generally occurring in impact craters." Their appearance is distinctly different from that of volcanic pits, which Mercury also has in abundance.
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The subducting oceanic plate melts as it reenters the mantle. The magma rises and erupts. This creates a volcanic mountain range near the coast of the continent. This range is called a continental arc.
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In fault-block mountains, tectonic plates slide past each other to create the mountain. In folded mountains, the tectonic plates slam together, forming the peaks and valleys we see in many famous mountain ranges, such as the Himalayas, the Andes, and the Swiss Alps.
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They tend to have very steep slopes and are symmetrical. They sometimes rise up to 10,000 feet above sea level and create some of the planet's most majestic mountains. The eruptions from this type of volcano can often be very violent, throwing rock, ash and lava high into the air.
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Water-filled crevasses may reach the bottom of glaciers or ice sheets and provide a direct hydrologic connection between the surface, where significant summer melting occurs, and the bed of the glacier, where additional water may moisten and lubricate the bed and accelerate ice flow.