Rocks and Landforms

ISBN-13: 9789401159852 / Angielski / Miękka / 2012 / 320 str.

John Gerrard

Opis

Geomorphology can be defined simply as the study of landforms. Landforms are the result of the interaction between what Ritter (1978) has called the driving and resisting forces. The driving forces or processes are the methods by which energy is exerted on earth materials and include both surface, geomorphological or exogenous processes and subsurface, geological or endogenous processes. The resisting forces are the surface materials with their inherent resistances determined by a complex combination of rock properties. Stated in these simple terms it would be expected that both sides of the equation be given equal weight in syntheses of landform evolution. However, this has not been the case. Until about the 1950s, geomorphology was mainly descriptive and concerned with producing time-dependent models of landscape evolution. Although the form of the land was the main focus, there was little detailed mention of process and scant attention to the properties of surface materials. There were, of course, exceptions. In the late 19th century G.K. Gilbert was stressing the equilibrium between landforms and processes. Many hydrologists were examining the detailed workings of river 'systems and drainage basins, culminating in the classic paper of Horton (1945).

Spis treści

1 General background.- Spatial scale.- Rock resistance.- Mechanisms of rock control.- Conclusions.- 2 Rock type and landform assemblages.- Igneous rocks.- Metamorphic rocks.- Sedimentary rocks.- Assessment of landform assemblages.- Spatial distribution of rock types.- Other rock classifications.- Conclusions.- 3 Landscape evolution and rock properties.- Slope angle, form and processes.- Denudation rates.- Slope development on horizontally bedded rocks.- Drainage basin properties.- Bedrock meanders.- Drainage patterns.- Conclusions.- 4 Rock strength and resistance.- Hardness and toughness.- Porosity, permeability and water absorption.- Strength and rock deformation.- Appraisal.- 5 Resistance to weathering.- Chemical weathering.- Chemical weathering of minerals.- Chemical weathering of rocks.- Physical weathering.- Conclusions.- 6 Weathering profiles and landform development.- Weathering front.- Weathering profile differentiation.- Weathering grades.- Weathering depths.- Weathering and the water table.- Spatial patterns of weathering profiles.- Duricrusts.- Weathering profiles and slope form.- Weathering and rock strength.- Weathering and slope instability.- Threshold slopes.- 7 Instability in jointed and fissured rock.- Characteristics of jointed rock.- Unloading joints and rebound phenomena.- Models of jointed rock behaviour.- Rock mass strength classifications.- Strength equilibrium slopes.- Modes of rock failure.- 8 Landforms on granitic rocks.- Inselbergs.- Domed inselbergs (bornhardts).- Tors (boulder inselbergs).- Landscape types.- Conclusions.- 9 Properties and landforms of mudrocks.- Terminology of mudrocks.- Composition of mudrocks.- Consolidation and unloading of mudrocks.- Consistency limits.- Microstructure.- Macrostructure.- Shear strength.- Weathering effects.- Swelling and shrinkage.- Landslides and slope development.- Mudslides.- Sensitive clays.- Conclusions.- 10 A rock-landform synthesis.- Landforms of glacial erosion.- Marine cliffs and shore platforms.- Rocks, landforms and climate.- Conclusions.