Kinds of Lava Flow
  Kinds of
Lava Flows		 Disaster
Agencies
 

 
 
               
USGS Photograph   USGS Photograph  
A'a (Ah-Ah) Lava Flow
 Pahoehoe flow  
In this kind of lava flow, pieces of cooled lava ride on the top of a melted core of thick rock. This thick core is dragged downhill by gravity. As the pieces of cooled lava roll downhill they are burried by the hot molten inside layer. Lava is an Italian word and means stream. Lava flows like this one flow as a stream of lava.  
        USGS Photograph  
USGS Photograph  
Basalt Lava   Pillow Lava  
Basalt is a hard volcanic rock that has a small amount of the chemical element silica. The flow of basaltic lava is faster than most lava because it is made up of thinner mixtures of silica. That makes it easier for basaltic lava to flow. Pillow lava forms when basalt lava reaches the ocean. A glassy bendable crust forms over the outside of the blob of lava until the pressure builds up and forces the blob to ooze out. A new pillow of lava will form from the hot lava that escapes from the last pillow. Pillow lava runs in long streams along the floor of the ocean next to the land.  
USGS Photograph          
  USGS Photograph  
Littoral Cones   Lava Tube  
Littoral cones are made up of lava fagments that pile up when a lava flow reaches water. The cones are formed when the lava reaches the cold water and fragments of tephra are blown up into the air.   Natural tubes below the surface of the earth that lava flows through easily. They form when lava from when the top crust of pahoehoe lava flows harden.  
               
               
               
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Photographic Citations:
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Text Bibliography:

USGS Volcanoes: Volcano Picture Glossary
http://volcanoes.usgs.gov/Products/Pglossary/pglossary.html