Skip to main content
U.S. flag

An official website of the United States government

EarthWord: Batholith

September 7, 2015

Despite sounding like something out of Harry Potter, a batholith is a type of igneous rock that forms when magma rises into the earth’s crust, but does not erupt onto the surface. The magma cools beneath the earth’s surface, forming a rock structure that extends at least one hundred square kilometers across (40 square miles), and extends to an unknown depth.

EarthWords is an on-going series in which we shed some light on the complicated, often difficult-to-pronounce language of science. Think of us as your terminology tour-guides, and meet us back here every week for a new word!

Image: Moon over Half Dome
Moonrise over Yosemite’s Half Dome, a prominent feature of the Sierra Nevada batholith. Image credit: Alex Demas, USGS.

Definition:

  • Despite sounding like something out of Harry Potter, a batholith is a type of igneous rock that forms when magma rises into the earth’s crust, but does not erupt onto the surface. The magma cools beneath the earth’s surface, forming a rock structure that extends at least one hundred square kilometers across (40 square miles), and extends to an unknown depth.

Etymology:

  • Bath– comes from the Greek for “deep,” and -lith, also from Greek, means “rock.” For instance, another name for the Stone Age is the Paleolithic age.

Use/Significance in the Earth Science Community:

  • Batholiths and other geologic formations are important to geologists and geophysicists, as various rock types have different meanings for natural hazards, mineral resources, and ecology.

USGS Use:

  • Knowing the origin and type of rock formations is helpful to a variety of USGS scientific projects. Batholiths are often subject to significant internal stress, which affects natural hazards like landslides and earthquakes. In addition, since batholiths are nearly always made of rocks that contain feldspar and quartz, knowing the location of batholiths helps with our mineral studies.

Next EarthWord: It’s like Twilight, but no worries, no werewolves or vampires here.

Hungry for some science, but you don’t have time for a full-course research plate? Then check out USGS Science Snippets, our snack-sized science series that focuses on the fun, weird, and fascinating stories of USGS science.

 

Get Our News

These items are in the RSS feed format (Really Simple Syndication) based on categories such as topics, locations, and more. You can install and RSS reader browser extension, software, or use a third-party service to receive immediate news updates depending on the feed that you have added. If you click the feed links below, they may look strange because they are simply XML code. An RSS reader can easily read this code and push out a notification to you when something new is posted to our site.

Was this page helpful?