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The word 'lava' is derived from the Latin verb lavare which means "to clean". The first time it was used in connection with extruded magma was apparently in a short account written by Francesco Serao of the eruption of Vesuvius which took place between May 14 and June 4 1737. In this he described "a flow of fiery lava" in analogy to the flow of water and mud down the flanks of the volcano following heavy rain.
The three main forms taken by flowing of lava are ‘a‘a, pāhoehoe, and pillow lava.
‘A‘a (from Hawaiian: ‘a‘ā meaning "stoney with rough lava", but also to "burn" or "blaze") is one of three basic types of flow lava. ‘A‘a is characterized by a rough or rubbly surface composed of broken lava blocks called clinker. The incredibly spiny surface of a recently solidified ‘a‘a flow makes walking very difficult and slow. The clinkery surface actually covers a massive dense core, which is the most active part of the flow. As pasty lava in the core travels downslope, the clinkers are carried along at the surface. At the leading edge of an ‘a‘a flow, however, these cooled fragments tumble down the steep front and are buried by the advancing flow. This produces a layer of lava fragments both at the bottom and top of an ‘a‘a flow. Accretionary lava balls as large as 3 m (10 ft) are common on ‘a‘a flows. ‘A‘a is usually of higher viscosity than pāhoehoe. Pāhoehoe can turn into ‘a‘a if it becomes turbulent due to meeting impediments or steep slopes.
Toes of a phoehoe advance across a road in Kalapana on the east rift zone of Kilauea Volcano in Hawai‘i.
Pāhoehoe (from Hawaiian, meaning "smooth, unbroken lava") is basaltic lavaLava is molten rock that a volcano expels during an eruption. Due to its high temperature, lava can be quite fluid when first exuded from a volcanic vent, but eventually solidifies into rock. However, the lava may flow many miles before solidification. that has a smooth, hummocky, or ropy surface. A p‘hoehoe flow typically advances as a series of small lobes and toes that continually break out from a cooled crust. The surface texture of pāhoehoe flows varies widely, displaying all kinds of bizarre shapes often referred to as lava sculpture.
Phoehoe lava near Black Crater in Lava Beds NMLava Beds National Monument located in Siskiyou and Modoc Counies, California, is the site of the largest concentration of lava tube caves in the United States. It was established as a United States National Monument on November 21, 1925. The monument lie.
Pillow lava is the rock type typically formed when lava emerges from an underwaterUnderwater sometimes shortened as U/W is a term describing the realm below the surface of water where the water exists in a natural feature (called a body of water) such as an ocean, sea, lake, pond, or river. Three quarters of the planet earth is covered volcanic vent or a lava flow enters the ocean. The viscous lava gains a solid crust immediately upon contact with the water, and this crust cracks and oozes additional large blobs or "pillows" as more lava emerges from the advancing flow. Since the majority of EarthEarth also known as the Earth or Terra is the planet on which we live, the third planet outward from the Sun. It is the largest of the solar system's terrestrial planets, and the only planetary body that modern science confirms as harbouring life. The pla's surface is covered by water, and most volcanoes are situated near or under it, pillow lava is actually very common.
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