Slope Processes

by

Simon M. Mudd

• LAST REVIEWED: 20 December 2016
• LAST MODIFIED: 13 January 2014
• DOI: 10.1093/obo/9780199874002-0083

Introduction

Much of the terrestrial surface of our planet is sloping. Rivers and glaciers occupy some of this terrain, but the vast majority of sloping grounds are hillslopes, or simply “slopes.” Slope processes are those that generate and transport soil or regolith. Both chemical and physical weathering occurs on and within slopes, and mass transport can be rapid and hazardous, as in the case of mass wasting, or gradual, as in the case of soil creep. Although humans have presumably pondered since prehistoric times why landscapes look the way they do, the formal study of slope processes has its roots in the 19th century, when scientists began debating how sediment is produced, the mechanisms and rates at which it is transported, and the manner in which sloping lands evolve through time. The field of slope processes continues today with the aim of predicting socially relevant phenomena such as slope failure and soil sustainability. Recent advances have been abetted by new techniques allowing unprecedented accuracy in characterizing the topography, chemistry, material properties, ages, and transport rates of sloping landscapes.

General Overviews

Slope processes bridge several scientific fields, and introductory discussions of slope processes tend to be distributed among texts in geomorphology, soil science, and hydrology. There are relatively few books dedicated specifically to slope processes. Arguably the classic text on slopes is Carson and Kirkby 1972. This book does not just summarize research on slope processes up to the point of publication, but it is also a major contribution of original scientific research, which includes several seminal mathematical models of slope evolution. For a historical perspective, Parsons 1988 provides an excellent overview of slope research up to the point of publication and is notable for its detailed discussions of how scientists working on slopes have come to their knowledge. The classic text on the mechanical properties of slope materials is Selby 1993. There are also several introductory textbooks on geomorphology that contain general overviews of slope processes. Summerfield 1991 provides some historical background and pays particular attention to large-scale patterns in slopes across continents, whereas Ritter, et al. 2002 and Anderson and Anderson 2010 focus on processes. Of the last two, Anderson and Anderson 2010 takes a more quantitative approach and provides a derivation of the mass balance of soil on a hillslope that serves as the basis of many numerical models of slope form. Finally, a useful reference for those interested in the direction of research into slope processes is Dietrich, et al. 2003. This contribution argues that in order to make robust predictions of sediment transport, erosion, and the evolution of landscapes, we require “sediment flux laws” that are physically based and relate forcing factors such as climate, topographic gradient, and biota to sediment transport.

• Anderson, R. S., and S. P. Anderson. Geomorphology: The Mechanics and Chemistry of Landscapes. Cambridge, UK: Cambridge University Press, 2010.

  DOI: 10.1017/CBO9780511794827

  An introductory textbook on geomorphology that contains a general overview of slope processes. Somewhat more quantitative than Ritter, et al. 2002; contains a derivation of conservation of mass on a hillslope and quantitative descriptions of slope stability. Appropriate for undergraduates with a solid mathematical background.

• Carson, M. A., and M. J. Kirkby. Hillslope Form and Process. Cambridge Geographical Studies 3. Cambridge, UK: Cambridge University Press, 1972.

  This is a seminal book on slope processes and is a major research contribution. It contains several original contributions on soil production, rock weathering, and slope stability. The book is written at an advanced, technical level.

• Dietrich, W. E., D. G. Bellugi, L. S. Sklar, J. D. Stock, A. M. Heimsath, and J. J. Roering. “Geomorphic Transport Laws for Predicting Landscape Form and Dynamics.” In Prediction in Geomorphology. Edited by P. R. Wilcock and R. M. Iverson, 103–132. Geophysical Monograph 135. Washington, DC: American Geophysical Union, 2003.

  DOI: 10.1029/135GM09

  This contribution outlines a strategy for research into the relationships between factors such as climate, biota, and topography with erosion and sediment transport. Investigation of sediment flux laws is a vibrant area of slope processes research, and this is a key reference for that branch of the science.

• Parsons, A. J. Hillslope Form. London: Routledge, 1988.

  DOI: 10.4324/9780203330913

  Provides the history of how scientists have come to understand slope processes, as developed up to the point of its publication. Although it lacks recent advances, a stimulating resource for those wishing to understand the evolution of the field.

• Ritter, D. F., R. C. Kochel, and J. R. Miller. Process Geomorphology. 4th ed. Boston: McGraw-Hill, 2002.

  A popular introductory textbook in geomorphology, with sections on slope processes. Somewhat less technical than Anderson and Anderson 2010, but with an approach that focuses more on slope processes, rather than on landscape patterns (as in Summerfield 1991). First published in 1978 (Dubuque, IA: W. C. Brown).

• Selby, M. J. Hillslope Materials and Processes. 2d ed. Oxford: Oxford University Press, 1993.

  This book focuses on slope stability and the mechanics of slope materials. First published in 1982.

• Summerfield, M. A. Global Geomorphology: An Introduction to the Study of Landforms. Harlow, UK: Longman Scientific & Technical, 1991.

  A popular introductory textbook in geomorphology, with sections on slope processes. Differs from Anderson and Anderson 2010 and Ritter, et al. 2002 in that it focuses on larger-scale (up to the scale of continents) patterns in slope forms.