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Aa (lava) Aa (from Hawaiian ‘a‘a, rough lava,) is one of three types of flow lava. The other two types of flow lava are pillow lava characterized by smooth rounded pillows formed where lava contacts water, and pahoehoe characterized by ropy surface. Aa is characterized by a rough rubbly surface composed of broken lava blocks called clinkers. www.ebroadcast.com.au /lookup/encyclopedia/aa/Aa_(lava).html   (189 words)

Volcano - MSN Encarta Lava is magma that breaks the surface and erupts from a volcano. Lava flows that have a continuous, smooth, ropy, or billowy surface are called pahoehoe (pronounced pah HOH ee hoh ee) flows, while aa (pronounced ah ah) flows have a jagged surface composed of loose, irregularly shaped lava chunks. Lava may also be described in terms of its composition and the type of rock it forms. encarta.msn.com /encyclopedia_761570122/Volcano.html   (790 words)

Types of Lava Flows Aa flows are emitted from the vent at high rates ranging to 50km an hour, often with much lava fountaining. However, the hallmark of aa lava flows is the very rough surface it produces when it cools and solidifies. In comparison with aa lava flows the surfaces of block lavas are much less rough and pitted than aa lava flows. library.thinkquest.org /17457/volcanoes/hazards.lavaflow.php   (297 words)

Hazard Slides Essentially, such flows are rivers of lava that congeal on the front and sides and form steep flow-fronts that are overridden by molten lava within the flows. A very smooth lava, known as volcanic glass is formed where lava is erupted as a partly congealed, slow-flowing mass, that cools too rapidly to crystallize as in the case of this flow near Mauna Ulu, Hawaii. Most lava flows are partly glass and silica-rich lavas are largely or entirely glass because of their slower rate of crystallization. www.ngdc.noaa.gov /seg/hazard/slideset/29/29_slides.shtml   (1900 words)

Lava Moore and his coworkers studied lava from the Mauna Ulu eruption They described pillow lavas as elongate, interconnected flow lobes that are elliptical or circular in cross-section (Moore, 1975). Aa is characterized by a rough, jagged, spinose, and generally clinkery surface. Aa lava flows tend to be relatively thick compared to pahoehoe flows. volcano.und.nodak.edu /vwdocs/vwlessons/lava.html   (1573 words)

Galapagos Volcanoes Lava plateaus of this type are located along the Snake River in Idaho, and the Columbia River in Washington and Oregon. Lava flows are streams of molten rock that pour onto the Earth's surface from an erupting vent. They are impacted by the wide range in speeds of the different lava types (basalt, andesite, dacite, and rhyolite), the lava discharge during eruptions, and the characteristics of the erupting vent and topography over which lava travels. www.galapagosonline.com /nathistory/Geology/Volcanoes.html   (1135 words)

Aa Lavas Aa lavas are characterized by surfaces that are a jumble of rough, clinkery and spinose, fragments, small chips to blocks measuring meters, and grade downward into massive lava. Aa lavas flow like a caterpillar tread, dumping talus over the snout and then overriding their own debris. In some cases, continued movement of the lava results in the overturning of the fold with the gentle slope on the lava source side and a steep slope away from it. www.geo.ua.edu /volcanology/lecture_notes_files/aa_lavas.html   (464 words)

directopedia : Directory : Arts : Movies : Titles : L : Lava Lava is molten rock that a volcano expels during an eruption. Solidified lava is known as igneous rock, although the term "lava flow" refers to the hardened formation. Aa or ‘A‘a (Hawaiian English, from Hawaiian: ‘a‘ā meaning "stoney with rough lava", but also to "burn" or "blaze") is one of three basic types of flow lava. www.directopedia.org /directory/Arts-Movies/Titles-L-Lava.shtml   (1273 words)

Lava Flows   (Site not responding. Last check: 2007-09-10) Aa lavas for example can leave the vent with a speed of about 50km. The surface the lava flows on will be changed by very quickly emplacing a layer of very new and hot rock onto the pre-existing terrain. The pre-existing terrain is destroyed by the lava flow. library.thinkquest.org /17457/volcanoes/hazards.lava.php   (99 words)

Lava Beds National Monument - Nature & Science Roughly ninety percent of the lava in the monument is basaltic. Aa is formed when pahoehoe cools and loses some of its gases. Aa is rough, sharp, and jagged; an excellent example is the Devils Homestead lava flow, which originated at Fleener Chimneys. www.nps.gov /labe/pphtml/subnaturalfeatures14.html   (625 words)

The Encyclopedia of Volcanoes - Part III - Summary Lava shields are low-angle volcanoes built by rapid effusions of basaltic lava and intrusions of magma at shallow depths. Sometimes a lava dome is transitional to a lava flow, in which case it is called a coulee. Individual lava flows can be enormous in terms of their volume, area, and length; and the flows may be turbulent. www.apnet.com /companions/012643140X/msie/Contents/part03.htm   (1162 words)

GORP Hawaii Volcanoes National Park - Volcanoes - Pahoehoe And Aa Lava A'a, the other type of lava, is either formed during cooler eruptions, or, more often, as a pahoehoe flow moves over the ground, it cools very slightly, and loses gas along the way. Over millions of years, the solid, fl lava flows become the red soil that is prominent on the older islands, Also noticeable at places where gasses are escaping are crusty white areas, deposits of salts, Sulfates, and opaline. The lava was very hot and gassy, so a surface that appears to be solid may only be the surface of a lava tube or gas bubble. gorp.away.com /gorp/resource/us_national_park/hi/vol_haw2.htm   (798 words)

Pu'u 'O'o lava flow hike At night, as the light fades, an orange glow from the lava may be reflected in the steam. This is a portion of the road that was spared in the lava flow. We were still about a mile from the actual lava flow, that is to say from where it entered the water. www.naturalbornhikers.com /PuuOolavaflow/PuuOolavaflow.htm   (1285 words)

Volcano Aa is a Hawai'ian word to describe how your feet would feel after walking on this surface. It is called pillow lava because of the round, soft-looking shape of it. Pillow lava has this shape because it cools rapidly as soon as it comes in contact with the water. www.cuca.k12.ca.us /rcms/smith/volcano/lava.htm   (171 words)

Lava - Wikipedia, the free encyclopedia Intermediate or Andesitic lavas are lower in aluminium and silica, and usually somewhat richer in magnesium and iron. A forested lava dome in the midst of the Valle Grande, the largest meadow in the Valles Caldera National Preserve. Lava domes are formed by the extrusion of viscous felsic magma. en.wikipedia.org /wiki/Lava   (2967 words)

Teacher's Guide to Craters of the Moon: Chapter 1 (5th-6th Grades)   (Site not responding. Last check: 2007-09-10) Aa flows have a rough, jagged surface and are extremely sharp. In Hawaiian, aa means "hard on the feet." Most lava flows emerge as pahoehoe and somewhere down the slope change into aa as the lava cools, loses much of its gas, and becomes thicker. Block lava is a variety of aa lava characterized by large irregular blocks of very dense lava with smooth surfaces. www.nps.gov /crmo/chap1a.htm   (1572 words)

The Virtual Cave: A'a Lava Lava flow composed of rough, jagged chunks, sometimes welded together but often loose, where the fragments are sometimes called clinker. Often a lava flow begins as pahoehoe lava and grades into aa as pieces of it start to cool and are carried along in the flow. It is rare for lava tubes to form in aa, but sometimes aa flows over older flows and enters pre-existing tubes through skylights. www.goodearthgraphics.com /virtual_tube/aalava.html   (134 words)

Lava Types   (Site not responding. Last check: 2007-09-10) Lava is fluid magma that flows onto the earth's surface. AA lava forms if the visousity of lava is high. The lava solidifies before gas is able to escape, and the gas bubbles become holes in the rock. www.angelfire.com /geek/mlopez/ltypes.html   (148 words)

Hawai'i: Aa and Pahoehoe Aa, on the left, and pahoehoe, on the right. Chemically the lava is the same, but aa lava is thicker and rougher. Pahoehoe lava tends to flow in thin (a couple of inches) sheets, while aa flows may be a several feet thick. jschumacher.typepad.com /photos/hawaii_day_one/hi37.html   (51 words)

Molossian Institute of Volcanology - Lava Beds National Monument Lava Beds National Monument, located in Siskiyou and Modoc Counties, California, is the site of the largest concentration of lava tube caves in the United States. Lava Beds National Monument is the site of the largest concentration of lava tube caves in the United States. Volcanic activity spewed forth molten rock and lava creating a rugged landscape, which was used as a natural fortress by Native Americans in the Modoc Indian War, 1872-73. www.molossia.org /volcanology/lavabeds.html   (789 words)

Galapagos Geology - Lava Flows Early in the flow, when the lava is hotter, these twists have the appearance of ropes, but later, as it cools and becomes more viscous, the twists are shaped more like entrails. The differences between pahoehoe and aa lavas are subtle, but one important aspect is the speed of flow. Stepping over the lava fragments results in loud clinking sounds (these rocks are often called "clinkers") and there is a much greater variety of plants growing there than can be found at Sullivan bay. www.rit.edu /~rhrsbi/GalapagosPages/Vulcanism5.html   (458 words)

Content Lava fountains may burst out of rifts on the main dome, and form cinder cones, which dot the surface of the volcano. The Hawaiian word for chunky lava is aa, or a-a, and is the word used universally by geologists everywhere to describe this type of lava. Lava had clothed the living tree in a winding sheet that burned it until it smoked at one end and spat a sizzle of juices out of each of its limbs and branches. www.fiu.edu /~harveyb/geological1.html   (2790 words)

Lava Lava flows are streams of molten rock material extruded onto the surface of the earth. The physical characteristics of lava flow depends on the chemistry of the lava, slope, duration of flow and the discharge from the vent. An AA-type lava flow (a Hawaiian term pronounced "ah ah") has a rough, rubbley surface and flows across the surface in a roller-like motion. www.uwsp.edu /geo/faculty/ritter/glossary/l_n/lava_flow.html   (96 words)

Physical Geology--Volcanism (Part 2) Aa lava is different from pahoehoe lava because ___. Aa flows are generally thinner and have smoother surfaces than pahoehoe flows. Shield volcanoes are common in ocean basins because lava composition is basaltic and nonexplosive. school.discovery.com /quizzes23/anitaho/geol101_volcanism2.html   (561 words)

Untitled On older aa lava beyond this are varied lehua forests, locally with a few other trees including mango and avocado. The transition from the aa lava onto deeply weathered soil is seen very conspicuously in the vegetation. Across a rough aa flow with sparse lehua, the vegetation changes to a dense guava brush with scattered tall slender lehua trees. www.botany.hawaii.edu /botany/guide/field16.htm   (2075 words)

Lava Caves   (Site not responding. Last check: 2007-09-10) The other type of cave is the result of a lava flow cooling and solidifying on the outside but the inside continuing to flow till the tube empties to some degree. The ideal type of lava for this to occur in is the fluid pahoehoe lava, this gives rise to many beautiful formations such as uniform channels, levees, stalactites, stalagmites, lava ropes, perfect tubes and smooth floors for walking. The more viscous aa lava is also often encountered in these caves that is generally much rougher and can result in a very uneven floor to the cave. www.ewpnet.com /azores/caves.htm   (401 words)

Catalog Page for PIA01431 As it is being emplaced, the outer margins of the lava flow cool and harden, but the interior remains hot and continues to flow down-hill. "Aa" lava flow surfaces are very rough to walk on-- thus the term "aa" probably refers to the sound a person might make when walking on a cooled/solidified aa flow in bare feet! The rough-surfaced flow across the lower half of the MOC image is interpreted to be an "aa" lava flow, and the smoother surface with a sinuous channel running down its center is interpreted to be a "pahoehoe" lava flow. photojournal.jpl.nasa.gov /catalog/PIA01431   (779 words)

Okmok 1997 The aa lava was very challenging to walk on, being extremely sharp, blocky, and irregular on every scale. After about a mile of aa hiking, we reached the edge of the older flow and dropped onto a sandy outwash plain, which led to the steaming fresh flows and the lake. The lava was still warm to the touch on its surface, and in the nooks and crannies it was hot. www.airbornescientific.com /okmok.htm   (3240 words)

Golden Gate Photo - Newberry Volcanic Gallery Lava Butte is one of the most prominent volcanic vents in the monument, rising 500 feet (150 meters) above the surrounding lava flows. Aa lava was more viscous and 'cooler' when it flowed. Aa is a Hawaiian word which may have originated from the mouths of the first people to walk across this rock. www.goldengatephoto.com /westus/newberry.html   (351 words)

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