1st Edition
Landforms and Geology of Granite Terrains
Table of Contents; Preface and acknowledgements;
1 Characteristics and foundations
1.1 Typical landforms and landscapes
1.2 Previous work
1.3 Occurrences of granite
1.4 Granite – definition and composition
1.5 Physical characteristics
1.6 Orthogonal fracture systems
1.7 Fractures and drainage patterns
2 Sheet fractures and structures
2.1 Terminology
2.2 Description and characteristics
2.3 Theories of origin
2.3.1 Exogenetic explanations
2.3.2 Endogenetic explanations
2.4 Summary
3 Weathering
3.1 Definition and significance
3.2 Physical disintegration
3.3 Chemical alteration
3.4 The course of weathering in granite
3.5 Controls of weathering
4 Plains – the expected granite form
4.1 Weathering and surfaces of low relief
4.2 Plains of epigene (subaerial) origin
4.2.1 Rolling or undulating plains
4.2.2 Pediments
4.2.3 Relationship between pediment and peneplain
4.3 Etch plains in granite
4.4 Very flat plains
4.5 Multicyclic and stepped assemblages
4.6 Exhumed plains
4.7 Summary
5 Boulders as examples of two-stage forms
5.1 The two-stage or etching mechanism
5.2 Boulders – morphology and occurrences
5.3 Subsurface exploitation of orthogonal fracture systems
5.4 Tectonic and structural forms
5.5 Types of peripheral or marginal weathering
5.6 Causes of peripheral weathering
5.7 Evacuation of grus
5.8 Boulders of epigene origin
5.9 Summary
6 Inselbergs and bornhardts
6.1 Definitions and terminology
6.2 Bornhardt characteristics
6.3 Theories of origin
6.3.1 Environment
6.3.2 The scarp retreat hypothesis
6.3.3 Tectonics and structure: faulting and lithology
6.3.4 Variations in fracture density
6.3.5 Differential subsurface weathering and the two-stage concept
6.4 Evidence and argument concerning origins of bornhardts
6.4.1 Contrasts in weathering between hill and plain
6.4.2 Incipient domes
6.4.3 Subsurface initiation of minor forms
6.4.4 Flared slopes and stepped inselbergs
6.4.5 Regional and local patterns in plan
6.4.6 Coexistence of forms associated with compression/shearing
6.4.7 Topographic settings
6.4.8 Occurrence in multicyclic landscapes
6.4.9 Fracture-defined margins
6.4.10 Age of inselbergs and bornhardts
6.5 Exhumed bornhardts and inselbergs
6.6 Antiquity and inselberg landscapes
6.7 Summary
Other granitic residuals and uplands
7.1 Isolated residuals
7.1.1 Nubbins
7.1.2 Castle koppies
7.1.3 Large conical forms or medas
7.1.4 Towers and acuminate forms
7.2 Massifs
7.3 Regions of all slopes topography
7.4 Discussion
8 Minor forms developed on steep slopes
8.1 Flared slopes
8.1.1 Description and characteristics
8.1.2 Origin
8.1.3 Changes after exposure
8.2 Fretted basal slopes and other variants
8.3 Scarp-foot weathering and erosion, and the piedmont angle
8.4 Rock platforms
8.4.1 Description
8.4.2 Origin
8.5 Scarp-foot depressions
8.5.1 Description
8.5.2 Origin
8.6 Flutings or grooves
8.6.1 Description
8.6.2 Origin
8.6.3 Surface or subsurface initiation?
8.6.4 Inversion
9 Minor forms developed on gentle slopes
9.1 Rock basins
9.1.1 Description
9.1.2 Nomenclature
9.1.3 Origin
9.1.4 Differentiation of major types
9.1.5 Evacuation of debris
9.1.6 Rate of development
9.2 Plinths and associated blocks and boulders
9.2.1 Description
9.2.2 Origin
9.3 Pedestal rocks
9.3.1 Terminology
9.3.2 Origin
9.4 Gutters or runnels
9.4.1 Terminology
9.4.2 Description
9.4.3 Origin
9.5 Rock levees
9.6 Rock doughnuts
9.6.1 Description
9.6.2 Origin
9.6.3 Evidence and argument
9.7 Fonts
10 Caves and tafoni
10.1 General statement
10.2 Caves associated with corestones and grus
10.3 Caves associated with fractures
10.4 Tafoni
10.4.1 Description
10.4.2 Process
10.4.3 Stages of development
10.4.4 Case-hardening and other veneers
10.5 Speleothems
11 Split and cracked blocks and slabs
11.1 Split rocks
11.1.1 Description
11.1.2 Origin
11.2 Parted and dislodged blocks
11.3 Dislocated slabs
11.3.1 A-tents
11.3.2 Overlapping slabs
11.3.3 Displaced slabs
11.3.4 Chaos
11.3.5 Wedges
11.3.6 Origin of the forms
11.3.7 Relationship of A-tents and pressure ridges
11.4 Polygonal cracking
11.4.1 Description
11.4.2 Previous interpretations
11.4.3 Evidence
11.4.4 Explanations
11.5 Tesselated pavements
12 Zonality, azonality and the coastal context
12.1 Introduction
12.2 Lithological zonality and azonality
12.3 Climatic zonality and azonality
12.4 The coastal context
13 Retrospect and prospect
Author Index; Location Index; Subject Index.Biography
Charles Rowland Twidale is presently a Visiting Fellow of the University of Adelaide, South Australia, and Honorary Professor of the University Institute of Geology "Isidro Parga Pondal" of the University of Coruña.
Juan Ramón Vidal Romaní is specialized in the interpretation of the origin of granitic forms in relation to their geodynamic environment. He is a Professor in Geodynamics at the University of Coruña and Director of the University Institute of Geology, "Isidro Parga Pondal".
