how do pahoehoe and a'a lava differ?
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The A'a / Pahoehoe difference: If lava cools slowly and does not move too fast it forms smooth ropy lava called pahoehoe. However, if it cools quickly and moves fast it can tear into clinkery pieces called a'a.
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The main difference between obsidian and onyx is how they are formed. Obsidian is formed when molten lava erupts from a volcano and cools quickly upon reaching land or water. ... Onyx, on the other hand, has a crystalline structure because it grew in the ground for a very long time. Onyx tends to have a duller finish.
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Apache tears originate from siliceous lava flows, lava domes or ash-flow tuffs, often in close association with or embedded in, gray perlite. The spherules occur as cores within perlite masses that typically exhibit texture of concentrically curved, onion-skin fractures.
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Lava is indeed very hot, reaching temperatures of 2,200° F or more. But even lava can't hold a candle to the sun! At its surface (called the "photosphere"), the sun's temperature is a whopping 10,000° F! That's about five times hotter than the hottest lava on Earth.
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Lava: Magma that reaches the earth's surface is called lava. It may be acidic or basic. Acidic lava is viscous, is lighter in colour and has higher silica content. Basic lava is non-viscous, is darker in colour and has lower silica content.
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Figure 8.23 shows the Mauna Loa Volcano. You can see that shield volcanoes do not have the steep mountainous sides of composite volcanoes. They have a very wide base and are much flatter on the top than composite volcano. ... Figure 8.23: The Mauna Loa Volcano in Hawaii is the largest shield volcano on Earth.
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There are also the kinds of mafic lava that are even a hotter than normal basaltic lava. One type is all ultra-mafic lava. Lava temperature tells us a lot about the different types of lava. Each brings important minerals and nutrients to the surface.
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Lavas, particularly basaltic ones, come in two primary types: pahoehoe (pronounced 'paw-hoey-hoey") and aa (pronounced "ah-ah"). Both names, like a number of volcanological terms, are of Hawaiian origin. A third type, pillow lava, forms during submarine eruptions.
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Felsic magma has more silica and alumina content, which makes magma more viscous. Mafic magma has less silica content and more iron and magnesium in it. ... Viscosity is determined by its composition and temperature: Felsic lava is more viscous than mafic lava.
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1) Lava flows are typically finer grained than intrusive igneous rocks. Why? ... Intrusive magma flows onto the Earth's surface and cools very slowly, allowing many small mineral grains to grow. C) The extrusive magma cools quickly so the mineral grains do not have time to grow.
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An is one that forms when lava cools on Earth's surface. Granite is a common intrusive rock in continents. If magma with the same composition reaches the surface, it forms extrusive rocks such as rhyolite and pumice (PUHM-ihs). Basalt (buh-SAWLT) is an extrusive igneous rock that forms the ocean floor.
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The distinction between magma and lava is all about location. When geologists refer to magma, they're talking about molten rock that's still trapped underground. If this molten rock makes it to the surface and keeps flowing like a liquid, it's called lava.
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Aphanitic (a = not, phaner = visible) rocks, in contrast to phaneritic rocks, typically form from lava which crystallize rapidly on or near Earth's surface. When extrusive rocks make contact with the atmosphere they cool quickly, so the minerals do not have time to form large crystals.
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A mountain is formed due to various geological processes like movement and opposition of tectonic plates but a volcano is formed around a vent that allows magma to reach the surface of the earth.
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A mountain results from various geological processes such as movement and opposition of tectonic plates. On the other hand, a volcano forms around a vent when magma flows out and reaches the surface of the earth.
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Pahoehoe lava. Pahoehoe is a smooth and continuous lava crust. Pahoehoe forms when the effusion rate is low and consequently the velocity of lava flow is slow2. Pahoehoe lava flow is usually at least 10 times slower than typical aa lava flow5.
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Lava flows are most likely to travel in this direction because the ground slopes downhill from the rift zone to the ocean. The area north of the lower east rift zone, which includes Pahoa, is also in Zone 2. ... No area on Kilauea is ranked Zone 4, but the area south of Kilauea's summit is classed as Zone 5.