,Tectonic Geomorphology
of Mountains:
A New Approach to Paleoseismology
William B. Bull
,ß 2007 William B. Bull
BL ACK WELL PU BL ISH I N G
350 Main Street, Malden, MA 02148-5020, USA
9600 Garsington Road, Oxford OX4 2DQ, UK
550 Swanston Street, Carlton, Victoria 3053, Australia
The right of William B. Bull to be identified as the Author of this Work has been asserted in accordance with the UK Copyright, Designs, and
Patents Act 1988.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means,
electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs, and Patents Act 1988, without
the prior permission of the publisher.
First published 2007 by Blackwell Publishing Ltd
1 2007
Library of Congress Cataloging-in-Publication Data
Bull, William B., 1930–
Tectonic geomorphology of mountains : a new approach to paleoseismology / William B. Bull.
p. cm.
Includes bibliographical references and index.
ISBN-13: 978-1-4051-5479-6 (hardback : alk. paper)
ISBN-10: 1-4051-5479-9 (hardback : alk. paper) 1. Morphotectonics. 2. Paleoseismology. I. Title.
QE511.44.B85 2007
551.43’2–dc22
2006100890
A catalogue record for this title is available from the British Library.
Set in 10.74/11pt AGaramond
by SPi Publisher Services, Pondicherry, India
Printed and bound in Singapore
by C.O.S Printers Pte Ltd
The publisher’s policy is to use permanent paper from mills that operate a sustainable forestry policy, and which has been manufactured from
pulp processed using acid-free and elementary chlorine-free practices. Furthermore, the publisher ensures that the text paper and cover board
used have met acceptable environmental accreditation standards.
For further information on
Blackwell Publishing, visit our website:
www.blackwellpublishing.com
, Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii
1 Scrunch and Stretch Bedrock Uplift
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Pure Uplift, Stretch and Scrunch Bedrock Uplift . . . . . . . . . . . . . . . . . 6
1.2.1 Isostatic and Tectonic Uplift . . . . . . . . . . . . . . . . . . . . . 6
1.2.2 Stretch and Scrunch Tectonics . . . . . . . . . . . . . . . . . . . . . 12
1.3 Landscape Responses to Regional Uplift . . . . . . . . . . . . . . . . . . . . 23
2 Concepts for Studies of Rising Mountains
2.1 Themes and Topics . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.2 The Fundamental Control of Base Level . . . . . . . . . . . . . . . . . . . . 28
2.2.1 Base Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.2.2 Base-Level Change . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.2.3 The Base Level of Erosion . . . . . . . . . . . . . . . . . . . . . . 31
2.2.4 The Changing Level of the Sea . . . . . . . . . . . . . . . . . . . . 33
2.2.5 Spatial Decay of the Effects of Local Base-Level Changes . . . . . . . . . . . 37
2.3 Threshold of Critical Power in Streams . . . . . . . . . . . . . . . . . . . . 39
2.3.1 Relative Strengths of Stream Power and Resisting Power . . . . . . . . . . . . 41
2.3.2 Threshold-Intersection Points . . . . . . . . . . . . . . . . . . . . . 42
2.4 Equilibrium in Streams . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.4.1 Classification of Stream Terraces . . . . . . . . . . . . . . . . . . . . 42
2.4.2 Feedback Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . 45
2.4.3 Dynamic and Static Equilibrium . . . . . . . . . . . . . . . . . . . . 46
2.5 Time Lags of Response . . . . . . . . . . . . . . . . . . . . . . . . . . 49
2.5.1 Responses to Pulses of Uplift . . . . . . . . . . . . . . . . . . . . . 50
2.5.2 Perturbations that Limit Continuity of Fluvial Systems . . . . . . . . . . . . 51
2.5.3 Lithologic and Climatic Controls of Relaxation Times . . . . . . . . . . . . 54
2.5.4 Time Spans Needed to Erode Landforms . . . . . . . . . . . . . . . . . 57
2.6 Tectonically-Induced Downcutting . . . . . . . . . . . . . . . . . . . . . . 58
2.6.1 Straths, Stream-Gradient Indices, and Strath Terraces . . . . . . . . . . . . . 58
2.6.2 Modulation of Stream-Terrace Formation by Pleistocene–Holocene Climatic Changes . 65
2.7 Nontectonic Base-Level Fall and Strath Terrace Formation . . . . . . . . . . . . . 66
2.8 Hydraulic Coordinates . . . . . . . . . . . . . . . . . . . . . . . . . . 69
3 Mountain Fronts
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
3.2 Tectonically Active Escarpments . . . . . . . . . . . . . . . . . . . . . . . 79
3.2.1 Faceted Spur Ridges . . . . . . . . . . . . . . . . . . . . . . . . 79
3.2.2 Mountain–Piedmont Junctions . . . . . . . . . . . . . . . . . . . . 83
3.2.3 Piedmont Forelands . . . . . . . . . . . . . . . . . . . . . . . . 86
of Mountains:
A New Approach to Paleoseismology
William B. Bull
,ß 2007 William B. Bull
BL ACK WELL PU BL ISH I N G
350 Main Street, Malden, MA 02148-5020, USA
9600 Garsington Road, Oxford OX4 2DQ, UK
550 Swanston Street, Carlton, Victoria 3053, Australia
The right of William B. Bull to be identified as the Author of this Work has been asserted in accordance with the UK Copyright, Designs, and
Patents Act 1988.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means,
electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs, and Patents Act 1988, without
the prior permission of the publisher.
First published 2007 by Blackwell Publishing Ltd
1 2007
Library of Congress Cataloging-in-Publication Data
Bull, William B., 1930–
Tectonic geomorphology of mountains : a new approach to paleoseismology / William B. Bull.
p. cm.
Includes bibliographical references and index.
ISBN-13: 978-1-4051-5479-6 (hardback : alk. paper)
ISBN-10: 1-4051-5479-9 (hardback : alk. paper) 1. Morphotectonics. 2. Paleoseismology. I. Title.
QE511.44.B85 2007
551.43’2–dc22
2006100890
A catalogue record for this title is available from the British Library.
Set in 10.74/11pt AGaramond
by SPi Publisher Services, Pondicherry, India
Printed and bound in Singapore
by C.O.S Printers Pte Ltd
The publisher’s policy is to use permanent paper from mills that operate a sustainable forestry policy, and which has been manufactured from
pulp processed using acid-free and elementary chlorine-free practices. Furthermore, the publisher ensures that the text paper and cover board
used have met acceptable environmental accreditation standards.
For further information on
Blackwell Publishing, visit our website:
www.blackwellpublishing.com
, Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii
1 Scrunch and Stretch Bedrock Uplift
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Pure Uplift, Stretch and Scrunch Bedrock Uplift . . . . . . . . . . . . . . . . . 6
1.2.1 Isostatic and Tectonic Uplift . . . . . . . . . . . . . . . . . . . . . 6
1.2.2 Stretch and Scrunch Tectonics . . . . . . . . . . . . . . . . . . . . . 12
1.3 Landscape Responses to Regional Uplift . . . . . . . . . . . . . . . . . . . . 23
2 Concepts for Studies of Rising Mountains
2.1 Themes and Topics . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.2 The Fundamental Control of Base Level . . . . . . . . . . . . . . . . . . . . 28
2.2.1 Base Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.2.2 Base-Level Change . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.2.3 The Base Level of Erosion . . . . . . . . . . . . . . . . . . . . . . 31
2.2.4 The Changing Level of the Sea . . . . . . . . . . . . . . . . . . . . 33
2.2.5 Spatial Decay of the Effects of Local Base-Level Changes . . . . . . . . . . . 37
2.3 Threshold of Critical Power in Streams . . . . . . . . . . . . . . . . . . . . 39
2.3.1 Relative Strengths of Stream Power and Resisting Power . . . . . . . . . . . . 41
2.3.2 Threshold-Intersection Points . . . . . . . . . . . . . . . . . . . . . 42
2.4 Equilibrium in Streams . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.4.1 Classification of Stream Terraces . . . . . . . . . . . . . . . . . . . . 42
2.4.2 Feedback Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . 45
2.4.3 Dynamic and Static Equilibrium . . . . . . . . . . . . . . . . . . . . 46
2.5 Time Lags of Response . . . . . . . . . . . . . . . . . . . . . . . . . . 49
2.5.1 Responses to Pulses of Uplift . . . . . . . . . . . . . . . . . . . . . 50
2.5.2 Perturbations that Limit Continuity of Fluvial Systems . . . . . . . . . . . . 51
2.5.3 Lithologic and Climatic Controls of Relaxation Times . . . . . . . . . . . . 54
2.5.4 Time Spans Needed to Erode Landforms . . . . . . . . . . . . . . . . . 57
2.6 Tectonically-Induced Downcutting . . . . . . . . . . . . . . . . . . . . . . 58
2.6.1 Straths, Stream-Gradient Indices, and Strath Terraces . . . . . . . . . . . . . 58
2.6.2 Modulation of Stream-Terrace Formation by Pleistocene–Holocene Climatic Changes . 65
2.7 Nontectonic Base-Level Fall and Strath Terrace Formation . . . . . . . . . . . . . 66
2.8 Hydraulic Coordinates . . . . . . . . . . . . . . . . . . . . . . . . . . 69
3 Mountain Fronts
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
3.2 Tectonically Active Escarpments . . . . . . . . . . . . . . . . . . . . . . . 79
3.2.1 Faceted Spur Ridges . . . . . . . . . . . . . . . . . . . . . . . . 79
3.2.2 Mountain–Piedmont Junctions . . . . . . . . . . . . . . . . . . . . 83
3.2.3 Piedmont Forelands . . . . . . . . . . . . . . . . . . . . . . . . 86
