Book contents
- Fluvial Megafans on Earth and Mars
- Fluvial Megafans on Earth and Mars
- Copyright page
- Contents
- Contributors
- Foreword
- Part I Introduction
- Part II Regional Studies
- 3 Megafans of Africa
- 4 Megafans of the Northern Kalahari Basin (Angola, Botswana, Namibia, Zambia)
- 5 The Chaco Megafans, South America
- 6 Megafans of the Pantanal Basin, Brazil
- 7 Geomorphic and Chronological Assessment of Aggradation Patterns on the Río Grande (Guapay) Megafan, Eastern Bolivia
- 8 Megafans of Southern and Central Europe
- 9 The Loire Megafan, Central France
- 10 Megafans of the Gangetic Plains, India
- 11 The Kosi Megafan, India
- 12 The Holocene Mitchell Megafan, Gulf of Carpentaria, Australia
- 13 Megafans of the Northern Victorian Riverine Plains, SE Australia
- Part III Applications in Other Sciences
- Part IV Megafans in World Landscapes
- Index
- References
3 - Megafans of Africa
from Part II - Regional Studies
Published online by Cambridge University Press: 30 April 2023
Book contents
- Fluvial Megafans on Earth and Mars
- Fluvial Megafans on Earth and Mars
- Copyright page
- Contents
- Contributors
- Foreword
- Part I Introduction
- Part II Regional Studies
- 3 Megafans of Africa
- 4 Megafans of the Northern Kalahari Basin (Angola, Botswana, Namibia, Zambia)
- 5 The Chaco Megafans, South America
- 6 Megafans of the Pantanal Basin, Brazil
- 7 Geomorphic and Chronological Assessment of Aggradation Patterns on the Río Grande (Guapay) Megafan, Eastern Bolivia
- 8 Megafans of Southern and Central Europe
- 9 The Loire Megafan, Central France
- 10 Megafans of the Gangetic Plains, India
- 11 The Kosi Megafan, India
- 12 The Holocene Mitchell Megafan, Gulf of Carpentaria, Australia
- 13 Megafans of the Northern Victorian Riverine Plains, SE Australia
- Part III Applications in Other Sciences
- Part IV Megafans in World Landscapes
- Index
- References
Summary
Mapping of Africa’s megafans according to a set of criteria (radii > 80 km, widths > 40 km; high topographic smoothness; result: n = 87), suggests a direct relationship between fluvial megafans and the thirty relatively young tectonic swells of the continent. Although ten are barren of megafans, fully 85% display this relationship and are thus named ‘swell-flank type’. Another control was also identified: almost two thirds of this group was related to swell flanks margined by a rift-related depression. Clustering is significant in this ‘the swell-and-rift’ subtype: 23 in South Sudan (Muglad-Melut troughs), nine in Kenya (Anza Rift), and four in southern Chad (Salamat, Dosseo, and Bongor rifts). The remainder (‘swell-flank only’ subtype) were found to be scattered widely. Only 3%, however, were exclusively related to rifts (e.g., the Okavango megafan of Botswana). Africa’s megafans total at least 1.2 Mkm2, average megafan unit area being 13,200 km2. Flanks of the largest swells (e.g., Congo Basin flanks of the East African swell) are devoid of megafans, perhaps because of enhanced recent uplift. Coasts are similarly devoid of megafans, possibly for the same reason. Cratonic blocks where swell growth is less prominent are also devoid. Africa’s largest rivers are associated with few megafans.
- Type
- Chapter
- Information
- Fluvial Megafans on Earth and Mars , pp. 23 - 47Publisher: Cambridge University PressPrint publication year: 2023
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