Stephen Reynolds - Exploring Geology

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exploring

GEOLOGY

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About the Cover

Parcutin Volcano, located in the Mexican state of Michoacn, stands where a Mexican family once tilled a quiet corn field. For three weeks they had heard what sounded like thunder though no clouds were nearby. Then, on February 20, 1943, an open fissure appeared in the field, and trees began to tremble. The ground hissed and swelled as sulfurous smoke and gray ash rose from the fissure. Volcanic fragments and blobs of magma were thrown skyward, from sand-sized grains carried upward by the winds to large volcanic bombs more than a meter in diameter that crashed around the volcanic vent. By the next day, a volcanic cone 50 m high stood in what had been the corn field the day before.

The cone erupted for nine years, giving scientists the unusual opportunity of witnessing the birth, life, and cessation of a volcano. What scientists witnessed was the steady growth of the cinder cone for the first year, with eruptions of lava increasing in frequency with time.

When the volcano became dormant in 1952, the cone had reached a height of 1,391 feet and almost a third of a cubic mile of lava had been erupted onto the surface. The town of San Juan Parangaricutiro was buried; only the steeples of its church remain above the dark, solidified lava flows. Ash had spread over many square miles of the surrounding countryside, blanketing vegetation and forcing local residents to settle elsewhere. The farmer who had first watched the birth of Parcutin planted a sign on his field before leaving: This volcano is owned and operated by Dionisio Pulido.

Parcutin lies within the broad Trans-Mexican Volcanic Belt, an almost east-west-trending swath of volcanoes that crosses the southern part of Mexico south of Mexico City. The volcanic belt is created as the Rivera and Cocos oceanic plates subduct beneath the southwestern edge of the North American plate.

Cover photograph by Michael Collier

Michael Collier received his BS in geology at Northern Arizona University, MS in structural geology at Stanford, and MD from the University of Arizona. He rowed boats commercially in Grand Canyon in the 70s and 80s, and then practiced family medicine in northern Arizona. Collier has published books about the geology of Grand Canyon, Death Valley, Denali, and Capitol Reef National Park. He has authored books on the Colorado River basin, glaciers of Alaska, and climate change in Alaska, as well as a three-book series on American mountains, rivers, and coastlines. As a special projects writer with the USGS, he produced books about the San Andreas fault, the downstream effects of dams, and climate change. Colliers photography has been recognized with awards from the USGS, the National Park Service, the American Geosciences Institute, and the National Science Teachers Association.

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EXPLORING GEOLOGY

Published by McGraw Hill LLC, 1325 Avenue of the Americas, New York, NY 10121. Copyright 2022 by McGraw Hill LLC. All rights reserved. Printed in the United States of America. Previous editions 2019, 2016, and 2013. No part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written consent of McGraw Hill LLC, including, but not limited to, in any network or other electronic storage or transmission, or broadcast for distance learning.

Some ancillaries, including electronic and print components, may not be available to customers outside the United States.

This book is printed on acid-free paper.

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ISBN 978-1-265-31622-8

MHID 1-265-31622-8

Cover Image: Michael Collier

All credits appearing at the end of the book are considered to be an extension of the copyright page.

The Internet addresses listed in the text were accurate at the time of publication. The inclusion of a website does not indicate an endorsement by the authors or McGrawHill LLC, and McGrawHill LLC does not guarantee the accuracy of the information presented at these sites.

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