Encyclopedia of Planetary Landforms

2015 Edition
| Editors: Henrik Hargitai, Ákos Kereszturi


  • Henrik Hargitai
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-3134-3_560


Slopes are inclined surfaces.



Slope Gradient

Slope gradient is the inclination of the surface of the soil from the horizontal. If the difference in elevation (rise) is 1 m over a horizontal distance (run) of 100 m, slope gradient is 1 %. A slope of 45° is a slope of 100 %, because the difference in elevation between two points 100 m apart horizontally is 100 m on a 45° slope (Soil Survey Division Staff 1993). Savigear ( 1965) proposed the following slope classes: lowland flats (0–1° slope gradient), flat (1–2°), slope (2–40°), and cliff (>40°). Slope and terrain classes for soil survey in the USA are described in Table 1. See also Acton et al. ( 1976) for a somewhat different classification.
Slopes, Table 1

Slope and terrain classes for soil survey in the USA (After Soil Survey Division Staff 1993)

Classes simple slopes

Complex slopes (terrain)

Slope gradient limits

Percent (%) (rise/run)

Approx. degree (angle)

Nearly level

Nearly level



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  1. Acton DF et al. (1976) Landform Classification. Landform mapping systems subcommittee of the canada soil survey committee. http://www.pedosphere.ca/resources/CSSC3rd/chapter18.cfm
  2. Aharonson O, Zuber MT, Rothman DH (2001) Statistics of Mars’ topography from the Mars Orbiter Laser Altimeter: slopes, correlations, and physical models. J Geophys Res E 106(E10):23723–23735CrossRefGoogle Scholar
  3. Burke K, Fegley B, Sharpton VL (1994) Are steep slopes on Venus preserved as a result of chemical cementation of pore-spaces in surface rocks? Lunar Planet Sci Conf XXV:201–202, HoustonGoogle Scholar
  4. Butzer KW (1965) Geomorphology from the Earth. Harper and Row, New YorkGoogle Scholar
  5. Chorley RJ, Schumm SA, Sugden DE (eds) (1985) Geomorphology. Methuen, London/New YorkGoogle Scholar
  6. Connors C (1995) Determining heights and slopes of fault scarps and other surfaces on Venus using Magellan stereo radar. J Geophys Res 100(E7):14361–14381. doi:10.1029/95JE01134CrossRefGoogle Scholar
  7. JPL (2007) MSL landing site selection user’s guide to engineering constraints. JPL, California Institute of Technology. http://marsoweb.nas.nasa.gov/landingsites/msl/memoranda/MSL_Eng_User_Guide_v4.5.1.pdf
  8. King LC (1962) The morphology of the Earth. Oliver and Boyd, EdinburghGoogle Scholar
  9. Kolka RK, Thompson JA (2007) Wetland geomorphology, soils, and formative processes. In: Batzer DP, Sharitz RR (eds) Ecology of freshwater and estuarine wetlands. University of California Press, Berkeley, pp 7–42CrossRefGoogle Scholar
  10. Kreslavsky MA, Head JW (1999) Kilometer-scale slopes on Mars and their correlation with geologic units: initial results from Mars Orbiter Laser Altimeter (MOLA) data. J Geophys Res 104(E9):21911–21924CrossRefGoogle Scholar
  11. Kreslavsky MA, Head JW (2003) North–south topographic slope asymmetry on Mars: evidence for insolation-related erosion at high obliquity. Geophys Res Lett 30(15):1815. doi:10.1029/2003GL017795CrossRefGoogle Scholar
  12. Kreslavsky MA, Head JW, Marchant DR (2008) Periods of active permafrost layer formation during the geological history of Mars: implications for circum-polar and mid-latitude surface processes. Planet Space Sci 56:289–302CrossRefGoogle Scholar
  13. Moore JM, Sullivan RJ, Chuang FC, Head JW III (2001) Landform degradation and slope processes on Io’ the Galileo view. J Geophys Res 106(El2):33223–33240CrossRefGoogle Scholar
  14. Rosenburg MA, Aharonson O, Head JW, Kreslavsky MA, Mazarico E, Neumann GA, Smith DE, Torrence MH, Zuber MT (2011) Global surface slopes and roughness of the Moon from the Lunar Orbiter Laser Altimeter. J Geophys Res 116:E02001. doi:10.1029/2010JE003716Google Scholar
  15. Savigear RAG (1965) A technique of morphological mapping. Ann Assoc Am Geogr 55:514–538. doi:10.1111/j.1467-8306.1965.tb00532.xCrossRefGoogle Scholar
  16. Sharpton VL, Head JW III (1985) Analysis of regional slope characteristics on Venus and Earth. J Geophys Res 90(B5):3733–3740CrossRefGoogle Scholar
  17. Soil Survey Division Staff (1993) Soil survey manual, Soil Conservation Service. U.S. Department of Agriculture Handbook 18. Washington, DCGoogle Scholar
  18. Talebi A, Troch PA, Uijlenhoet R (2007) A steady-state analytical slope stability model for complex hillslopes. Hydrol Processes 21. doi:10.1002/hyp.6881Google Scholar

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© Springer Science+Business Media New York 2015

Authors and Affiliations

  1. 1.NASA Ames Research Center/NPPMoffett FieldUSA