|
Extrusive igneous rocks, or volcanics, form when magma makes its way to Earth's surface. The molten rock erupts or flows above the surface as lava, and then cools forming rock. The lava comes from the upper ... Basalt is the most common type of extrusive igneous rock and the most common rock type at the Earth's surface.
|
www.windows.ucar.edu/tour/link=/earth/geology/ig_extrus...
www.windows.ucar.edu/tour/link=/earth/geology/ig_extrusive.html
|
|
|
|
|
|
A photo gallery of intrusive and extrusive rocks by Geology.com ... Andesite is a fine-grained, extrusive igneous rock composed mainly of plagioclase with other minerals such as hornblende, pyroxene and biotite. The specimen shown is about two inches (five centimeters) across.
|
geology.com/rocks/igneous-rocks.shtml
geology.com/rocks/igneous-rocks.shtml
|
|
|
|
Igneous rocks—those which originate from a hot, fluid state—fall naturally into two categories, extrusive and intrusive. Extrusive rocks are erupted from volcanoes or seafloor fissures, or they freeze at shallow depths. ... Some of these rocks are clastic—composed of rock and mineral fragments, or clasts,
|
geology.about.com/od/more_igrocks/ig/extrusives/
geology.about.com/od/more_igrocks/ig/extrusives/
|
|
|
Igneous Rock page (I. Rocks) - This page describes how igneous rocks are formed and how they are made. Extrusive Rock page (E. Rocks) - This page describes ...
|
library.thinkquest.org/20151/
|
|
They are called extrusive igneous rocks. Basalt is an example of this type of rock. Obsidian is an example of another extrusive igneous rock that cooled so fast that it has no crystals and looks like shiny, black glass.
|
library.thinkquest.org/J002289/igneous.html
library.thinkquest.org/J002289/igneous.html
|
|
This is a piece of pumice, a type of rock that forms when lava quickly cools on the surface of the earth. When lava cools quickly, it doesn't have a chance to form the large crystals you find in many ... Because they originate from lava, both granite and pumice are truly "born of fire." Both are known as igneous rocks.
|
www.pbs.org/wgbh/nova/hawaiiactivity/lava1.html
|
|
Extrusive igneous rocks show up as volcanos. Intrusives exist as bodies of igneous rock below ground, such as batholiths, dikes, and sills. ... ; Go to Igneous Rock Home Page;
|
csmres.jmu.edu/geollab/Fichter/IgnRx/Weblink.html
|
|
Intrusive rocks have a coarse grained texture. Extrusive Igneous Rocks:; Extrusive, or volcanic, igneous rock is produced when magma exits and cools outside of, or very near the Earth's surface. These are the rocks that form at erupting volcanoes and oozing fissures. ... Andesite -- extrusive igneous rock...
|
vulcan.wr.usgs.gov/LivingWith/VolcanicPast/Notes/igneou...
vulcan.wr.usgs.gov/LivingWith/VolcanicPast/Notes/igneous_rocks.html
|
|
