Hogback (geology)

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Hogback west of Denver, Colorado. It is formed by the more erosionally resistant Lytle and South Platte Formations protecting the softer, slope-forming Morrison Formation.

A hogback is a homoclinal ridge composed of steeply tilted strata of rock protruding from the surrounding area. The name comes from the ridge resembling the ridge between the shoulders of a hog. In many cases, the two strata that compose a hogback are different types of sedimentary rock with differing weathering rates. The softer rock erodes more quickly than overlying hard rock. Over time, the softer rock retreats to a point where the hard and soft rock strata are adjacent. This creates cliffs that steepen as the softer rock continues to erode. The defining characteristics of a hogback a steep dip slope that is greater than 30° - 40° with a near symmetric slope on each ridge face. A cuesta is a homoclinal ridge with a more gentle dip slope.^[1]^[2]

[edit] References

Easterbrook, D. J. (1999) Surface processes and landforms. (Second Ed). Prentice Hall, Upper Saddle River, New Jersey.

^ Divener, V.. Structural Control of Fluvial Landscapes. Crustal Structures and Landforms (course notes). Long Island University C.W. Post Campus. Retrieved on 2008-03-16. “Homoclinal ridges are called cuestas where bedding dip is gentle [and] hogbacks where steep (>30-40 degree).”
^ Cuesta, or homoclinal ridge (geology). Britannica Online Encyclopedia. Retrieved on 2008-03-16. “Cuestas with dip slopes of 40°–45° are usually called hogback ridges.”