Off-trail adventures in Baja California: exploring landscapes and geology on gulf shores and islands

272 Pages·2014·3.925 MB·English

by  Johnson, Markes E

Off-Trail Adventures in
Baja California
Books by Markes E. Johnson
Discovering the Geology of Baja California: Six Hikes on the Southern
Gulf Coast (2002)
Atlas of Coastal Ecosystems in the Western Gulf of California (2009),
coeditor with Jorge Ledesma-Vázquez
Available from the University of Arizona Press
Off-Trail
Adventures in
Baja California
Exploring Landscapes and Geology on
Gulf Shores and Islands
Markes E. Johnson
tucson
For Jorge Ledesma-Vázquez and David H. Backus,
who shared much of the journey.
The University of Arizona Press
© 2014 The Arizona Board of Regents
All rights reserved
www.uapress.arizona.edu
Library of Congress Cataloging-in-Publication Data
Johnson, Markes E.
Off-trail adventures in Baja California : exploring landscapes and geology
on gulf shores and islands / Markes E. Johnson.
pages cm
Includes bibliographical references and index.
ISBN 978-0-8165-2130-2 (pbk. : alk. paper)
1. Geology—Mexico—Baja California (Peninsula)—Guidebooks.
2. Baja California (Mexico : Peninsula)—Guidebooks. I. Title.
QE203.B34J65 2014
557.2’2—dc23
2013034783
Manufactured in the United States of America on acid-free, archival-quality paper
containing a minimum of 30% post-consumer waste and processed chlorine free.
19 18 17 16 15 14 6 5 4 3 2 1
Contents
List of Illustrations vii
Acknowledgments xi
Advice to the Reader xiii
1. Cataviña: Gateway to a Peninsular Wilderness 3
2. Investigations on a Guardian Angel 21
3. Great Sand Ramp at Km 41 48
4. San Francisquito’s Ancient Bay 65
5. Lost Lagoons of Bahía Concepción 91
6. Intersection of Fractures at El Mangle 114
7. Coral Reef on a Volcano at Isla Coronados 140
8. Song of the Amazon on Isla Monserrat 164
9. Riding Out Ancient Storms on Isla Cerralvo 185
10. Zen Aesthetics and the Big Picture: An Epilogue 207
Notes 211
Glossary of Geological and Ecological Terms 219
Geological and Biological References 225
Index 231

Illustrations
Figures
1. Block in rampart wall, Imperial Palace, Tokyo, showing spheroidal
weathering 13
2. Cross section of Farallon Plate against the western margin of North
America 16
3. Travertine deposit showing contemporary wood and plant material
undergoing fossilization 19
4. Closed lagoons at south end of Isla Angel de la Guarda 34
5. Thrombolites on little lagoon, Isla Angel de la Guarda 35
6. Sea stacks on southeast shores of Isla Angel de la Guarda 40
7. Polygonal cracks on stromatolitic mats around big lagoon, Isla
Angel de la Guarda 43
8. Fossil oysters from south end of Isla Angel de la Guarda 46
9. Gravel road south of Bahía de los Angeles, showing sand ramp in
background 49
10. Backus and Tierney in field with sandburs 57
11. Backus seated on dune near top of sand ramp 60
12. Pliocene fossils from San Francisquito 70
13. View from landing field at San Francisquito to southwest basin
rim 74
14. Field sketch showing former hot spring colonized by marine
bivalves 84
15. Conglomerate composed of boulders representing river deposit
under flood conditions 86
16. Part of 1968 McFall map for region around Bahía Concepción 95
17. Comparison between modern and fossil shells of the same gastropod
species 98
18. Amphitheater eroded in layers of chert formation 102
19. Fossil root casts, with inset photo showing growth rings 104
20. High canyon walls on Old San Sebastián Road 106
vii
viii Illustrations
21. Arrowhead fashioned from chert from base of Concepción
Peninsula 113
22. Stratigraphic columns in Pliocene sequence 125
23. Plant debris from Pliocene opalite at El Mangle 129
24. View south over Pliocene strata on margin of Cerro Mencenares
complex 130
25. View of Isla Coronados looking east from Punta el Bajo 142
26. Fossil pen shell preserved in growth position 149
27. Students entering opening to Pleistocene lagoon below quiescent
volcano on Isla Coronados 152
28. Outcrop showing fossil corals preserved in growth position, with
inset showing immature coral colony 156
29. Ascent of Pleistocene volcano on Isla Coronados 160
30. Fossil echinoids 168
31. Rotated fault block of Miocene Comondú rocks 169
32. Sea cliff and wave-cut platform in andesitic agglomerate on west
shore of Isla Monserrat 174
33. Scree slope on west side of Isla Monserrat covered by veneer of
broken limestone 175
34. North beach on Isla Monserrat with extensive shell debris 180
35. Coarse debris derived from crushed rhodoliths in white seam at
Paredones Blancos 191
36. Small arroyos and connected fan deltas on east coast of Isla
Cerralvo 197
37. Pliocene conglomerate at Los Carillos with fossil gastropods and
worn pecten shells 199
38. Fossil rhodoliths among boulders at Los Carillos 200
39. Historical storm tracks from recent hurricanes striking Baja Califor-
nia peninsula and Gulf of California 206
40. Rock garden from Nanzen-ji complex in Kyoto, Japan 209
Maps
1. Localities in Baja California and associated islands 4
2. Geology of Isla Angel de la Guarda 28
3. Topography of region around El Quelital (Km 41) 52
4. Topography and geology of San Francisquito basin 67
5. Topography and geology at base of Concepción Peninsula 101
Illustrations ix
6. Topography of South and North Loreto basins and Mencenares
volcanic complex (MVC) 116
7. Topography and geology of area around El Mangle 119
8. Topography and geology of Isla Coronados 144
9. Topography and geology of Isla Monserrat 166
10. Topography of Isla Cerralvo 188
Tables
1. Pleistocene bivalves (phylum Mollusca) from the south side of Isla
Coronados 150
2. Pleistocene gastropods (phylum Mollusca) from the south side of
Isla Coronados 151
Plates
1. Granite boulders and desert plants southeast of Cataviña
2. Aerial view to northeast over south end of Isla Angel de la Guarda
3. View north from sand ramp with Bahía de los Animas and Isla Angel
de la Guarda in the distance
4. Aerial view east over sand ramp
5. Aerial view east over San Francisquito basin
6. View north from San Francisquito road
7. Aerial view east over south end of Concepción Peninsula
8. View southwest from Punta el Mangle
9. View north to Punta el Mangle
10. Aerial view east over radial topography of Cerro Mencenares
volcanic complex
11. Humboldt squid in death throes
12. Aerial view east over Isla Coronados
13. View north to plateau on Isla Monserrat
14. Aerial view southeast over Isla Monserrat
15. Paredones Blancos on west coast of Isla Cerralvo
16. Granite platform and overlying Pliocene ramp on Isla Cerralvo