Steep and unstable slopes can produce LANDSLIDES AND MUDFLOWS , forming coarse-grained rocks.
Landslides occur because of a compromise in the natural stability of a slope. It is characterized by masses of earth and rock rapidly moving down fast in the slant. Mudflows, are also a form of mass wasting attributed by extreme surging flow of liquefied debris and water.
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Magma erupted on the surface can form a LAVA FLOW that cools quickly, resulting in volcanic glass.
Lava flow is a process in volcanic eruptions. Lava flows are oozing streams of molten rock from an erupting vent. Lava runs according to its type and viscosity, steepness of the landscape, whether the lava is flowing as a broad sheet through a tube or channel, and how rapid the production of lava is. When the lava cools immediately, it solidifies without crystallization and becomes a glasslike rock.
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Some volcanic ash rises vertically in an ERUPTION COLUMN , cools before accumulating on the surface, and forms deposits that are pegmatite.
Eruption column is emitted during an explosive eruption, as a column or a vertical cloud of ash and tephra in gases. It forms as crystalline granite measuring from several centimeters up to several meters high when it cools before accumulating.
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Some volcanic ash forms PYROCLASTIC FLOW that accumulate while hot and can become WELDED to some extent.
Pyroclastic flow is also referred to as pyroclastic density current or pyroclastic cloud. It is tephra as hot as 1000 degrees Celsius, swiftly moving away from the volcano speeding 700 km/h at most. Many pyroclastic flows that are thick become welded—compact and consolidated.
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