In
geology, a stock is an
igneous intrusion that has a surface exposure of less than ,
[Whittow, John (1984). ''Dictionary of Physical Geography''. London: Penguin, 1984, p. 513. .] differing from
batholiths
A batholith () is a large mass of intrusive igneous rock (also called plutonic rock), larger than in area, that forms from cooled magma deep in Earth's crust. Batholiths are almost always made mostly of felsic or intermediate rock types, such ...
only in being smaller. A stock has a
discordant relationship with the rocks that it intrudes. Many stocks are
cupolas
In architecture, a cupola () is a relatively small, most often dome-like, tall structure on top of a building. Often used to provide a lookout or to admit light and air, it usually crowns a larger roof or dome.
The word derives, via Italian, fr ...
of hidden batholiths.
Some circular or elliptical stocks may be
volcanic plugs, which fill the vents of now extinct volcanoes.
A boss is a small stock.
Examples
* the Alta and Clayton Peak stocks (composed of
granodiorite
Granodiorite () is a coarse-grained (phaneritic) intrusive igneous rock similar to granite, but containing more plagioclase feldspar than orthoclase feldspar.
The term banatite is sometimes used informally for various rocks ranging from gr ...
), near
Park City, Utah
* the Hellroaring Creek and
Salal Creek stocks (of
granite-granodiorite and
quartz monzonite, respectively) in
British Columbia, Canada
* the Céret stock (of
gabbro
Gabbro () is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is ch ...
and
diorite) in
Pyrénées-Orientales, France
* the Parashi stock (of
tonalite) in
La Guajira Department, Colombia
* stocks of
syenite in the Caldera de Tejeda on
Gran Canaria
*
Ailsa Craig
Ailsa Craig (; sco, Ailsae Craig; gd, Creag Ealasaid) is an island of in the outer Firth of Clyde, west of mainland Scotland, upon which microgranite has long been quarried to make curling stones. The now-uninhabited island comprises the ...
granitic boss, which forms a volcanic plug, in Scotland
References
Igneous intrusions
{{volcanology-stub