Wall rock is the rock that constitutes the wall of an area undergoing geologic activity. Examples are the rock along the neck of a
volcano
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
On Earth, volcanoes are most often found where tectonic plates ...
, on the edge of a
pluton
In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...
that is being emplaced, along a fault plane, enclosing a mineral deposit, or where a
vein
Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated ...
or
dike is being emplaced.
In volcanoes, wall rock can often become broken off the wall and incorporated into the erupted
volcanic rock
Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic ...
as
xenolith
A xenolith ("foreign rock") is a rock fragment ( country rock) that becomes enveloped in a larger rock during the latter's development and solidification. In geology, the term ''xenolith'' is almost exclusively used to describe inclusions in ig ...
s. These xenoliths are important to
geologist
A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, althou ...
s because they can come from rock units that are otherwise not exposed at the Earth's surface.
See also
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Country rock (geology)
In geology, country rock is the rock native to an area, in contrast to any intrusion of viscous geologic material, commonly magma, or perhaps rock salt (in salt domes) or unconsolidated sediments.
Magma is typically less dense than the rock i ...
ReferencesWordNet
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Rock formations