Sea-Level Change in the Gulf of Mexico

Preface

People in the early civilizations recognized that sea level has changed over time. Stories in ancient Greek and Hebrew described great floods of the sea. The presence of fossils and huge boulders well above present sea level were used as evidence. Much later, in the seventeenth century, Neptunism was prevalent among scientists. This theory held that there was a major fall in sea level. As more data were collected and naturalists became more sophisticated in their interpretation, it was recognized that phenomena such as earthquakes and volcanic eruptions could cause sea-level change. Finally, in the late nineteenth century, the famous scientist Eduard Suess recognized that sea level has changed globally; he termed this “eustatic” change. That is, sea level can change throughout the world, both upward and downward. The Gulf of Mexico is a mediterranean sea, a large water body surrounded by land. The Mediterranean Sea is an excellent example as are the Persian Gulf and the Red Sea. All of these large water bodies owe their origin to plate tectonics. How old is the Gulf of Mexico, how did it come about, and how has sea-level change influenced its present appearance? These and other topics will be discussed in this book. Humans populate all the coasts of the world, and changes in sea level that are experienced by coasts impact the nearby population. The topic of global warming, which can produce sea-level change, especially sea-level rise, is now in the media almost daily. As little as a couple of decades ago, people had no concern about global warming at all. This book is not aimed at a discussion of the causes of global warming but only at sea-level change, both its rise and its fall. There are many factors that can contribute to this condition, some of which are due to climate change and others that are not. All of these factors will be considered. The Gulf of Mexico coast is densely populated in the United States but much less so in Mexico and Cuba. More than 25 million people live along the Gulf, including large metropolitan areas around Houston inTexas and Preface viii P R E F A C E the Tampa Bay area in Florida. There are also extensive coastal reaches with little or no population including much of the Texas Gulf Coast and nearly all the Mexico Gulf Coast.The economy of the Gulf of Mexico coast is based largely on the petroleum industry, tourism, and shipping with a diminishing seafood industry a distant fourth. Sea-level change has and will have, a significant impact on these industries and therefore on the economy of the Gulf Coast. The contents of this book will provide the reader with a comprehensive discussion of sea-level change, its causes, types and rates, the geologic history of sea-level change, our present situation, and some potential effects in the future. Sea-level change is largely based on geological phenomena. Knowledge of that discipline is not required for a thorough understanding of this text. This book is written for the general public including coastal managers, government officials, coastal engineers, biologists, and others with an interest in this important and timely topic. Both the text and illustrations come from a wide range of sources; little is original with the author. The book is a synthesis of what we now know about sea-level change along the margins of this important body of water. The numerous references cited in books for research purposes are eliminated in favor of a brief list of related readings. Specific sources in the scientific literature are provided in the figure captions indicating their origin. I would be remiss without mentioning the several outstanding research efforts and subsequent publications on the Gulf of Mexico from various individuals and groups.The U.S. Geological Survey, the Florida Geological Survey and The University of Texas—Bureau of Economic Geology have led prominent efforts. Ervin Otvos of the Gulf Springs Research Laboratory in Mississippi has been a prolific researcher on the northern Gulf of Mexico coast. The Coastal Studies Institute of Louisiana State University has long been the dominant research group for the Mississippi River Delta, led by James Coleman and Harry Roberts.The most prominent group now working on the northern Gulf Coast down to the border with Mexico is that from the Department of Geology at Rice University led by John Anderson . He and his students have provided a great understanding of the Quaternary Period...