Skip to main content
Select Source:

Rockfall

Rockfall

Rockfall is a form of mass movement or mass wasting in which pieces of rock travel downward through some combination of falling, bouncing, and rolling after they are initially separated from the slope. The sizes of rockfall blocks can range from cubic centimeters to tens of thousand of cubic meters. Although some sliding may occur as the rock is becoming detached, sliding is a minor component of the process. Free fall typically occurs on slopes steeper than 76 degrees, bouncing on slopes between 45 and 76 degrees, and rolling on slopes below 45 degrees. Because slopes are commonly irregular, a rock may alternate between the three modes during its downslope movement. Talus slopes along the bases of cliffs are the products of uncounted rockfalls over thousands of years.

The size of rockfall blocks is controlled by bedding planes, joints, and fractures that form mechanical discontinuities and allow the blocks to become detached from the slope. Fracture lengths, and therefore rockfall volumes, tend to follow power law or fractal distributions, meaning that their numbers decrease exponentially as fracture length or rockfall volume increases. Field studies have also shown that freezing and melting of ice within cracks may control rockfall timing in some areas, although the falls generally seem to be more closely related to melting rather than ice wedging.

Extremely large rockfalls can constitute catastrophic mass movements because their weight and vertical fall distance (which combine to define the potential energy of the rock before it falls) produce potentially destructive kinetic energy. A large rockfall in Yosemite National Park during the summer of 1996, for example, involved two large rock slabs with a total volume of between 30,000 and 49,700 yd3 (23,000 and 38,000 m3) that became detached from a cliff face and became airborne 2,181 ft (665 m) above the valley floor. The estimated velocity of the slabs at impact was approximately 246268 mph (396431 kph) and the event was recorded on seismographs as far as 124 mi (200 km) away. The impact produced an air blast with estimated velocities as high as 246 mph, which snapped and uprooted trees, generated a dense cloud of dust that plunged the area into darkness, and killed a hiker. The catastrophic rock avalanches, such as those that destroyed the towns of Elm, Austria and Frank, Alberta probably also involved significant amounts of rockfall that evolved into rock avalanches as they moved downslope.

See also Landslide; Talus pile or Talus slope

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Rockfall." World of Earth Science. . Encyclopedia.com. 18 Apr. 2018 <http://www.encyclopedia.com>.

"Rockfall." World of Earth Science. . Encyclopedia.com. (April 18, 2018). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/rockfall

"Rockfall." World of Earth Science. . Retrieved April 18, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/rockfall

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

rockfall

rock·fall / ˈräkˌfôl/ (also rock fall) • n. a descent of loose rocks. ∎  a mass of fallen rock.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"rockfall." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 18 Apr. 2018 <http://www.encyclopedia.com>.

"rockfall." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (April 18, 2018). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/rockfall-0

"rockfall." The Oxford Pocket Dictionary of Current English. . Retrieved April 18, 2018 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/rockfall-0

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

rockfall

rockfall •landfall • pratfall • deadfall •rainfall • windfall • pitfall • icefall •nightfall • rockfall • shortfall •downfall • outfall • snowfall • dewfall •footfall • waterfall • overfall •keelhaul • guildhall • Whitehall •shorthaul • overhaul • catcall • recall •Rockall • rollcall • photocall • overcall •Bokmål • pub crawl • overall •coverall • Walsall • tattersall •headstall • bookstall • fingerstall •therewithal, wherewithal •gadwall • whitewall • Cornwall •firewall • caterwaul • Kirkwall

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"rockfall." Oxford Dictionary of Rhymes. . Encyclopedia.com. 18 Apr. 2018 <http://www.encyclopedia.com>.

"rockfall." Oxford Dictionary of Rhymes. . Encyclopedia.com. (April 18, 2018). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/rockfall

"rockfall." Oxford Dictionary of Rhymes. . Retrieved April 18, 2018 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/rockfall

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.