The Cast Iron Forest: A Natural and Cultural History of the North American Cross Timbers

By Richard V. Francaviglia

“A thoughtful, thorough, and updated account of this bio-region” from the author of From Sail to Steam: Four Centuries of Texas Maritime History, 1500-1900 (Great Plains Research).
 
Winner, Friends of the Dallas Public Library Award, Texas Institute of Letters, 2001
 
A complex mosaic of post oak and blackjack oak forests interspersed with prairies, the Cross Timbers cover large portions of southeastern Kansas, eastern Oklahoma, and north central Texas. Home to indigenous peoples over several thousand years, the Cross Timbers were considered a barrier to westward expansion in the nineteenth century, until roads and railroads opened up the region to farmers, ranchers, coal miners, and modern city developers, all of whom changed its character in far-reaching ways.
 
This landmark book describes the natural environment of the Cross Timbers and interprets the role that people have played in transforming the region. Richard Francaviglia opens with a natural history that discusses the region’s geography, geology, vegetation, and climate. He then traces the interaction of people and the landscape, from the earliest indigenous inhabitants and European explorers to the developers and residents of today’s ever-expanding cities and suburbs. Many historical and contemporary maps and photographs illustrate the text.
 
“This is the most important, original, and comprehensive regional study yet to appear of the amazing Cross Timbers region in North America . . . It will likely be the standard benchmark survey of the region for quite some time.” —John Miller Morris, Assistant Professor of Geography, University of Texas at San Antonio

• Language: English
• Publisher: Open Road Integrated Media
• Release date: Jun 28, 2010
• ISBN: 9780292789029

Book preview

THE CAST IRON FOREST

Corrie Herring Hooks Series, Number Forty-three

BY RICHARD V. FRANCAVIGLIA

The Cast Iron Forest

A NATURAL AND CULTURAL HISTORY OF THE NORTH AMERICAN CROSS TIMBERS

University of Texas Press

Austin

FRONTISPIECE: Cross Timbers Vista, Indian Territory, by Richard V. Francaviglia, 1998.

Copyright © 2000 by the University of Texas Press

All rights reserved

Printed in the United States of America

First edition, 2000

Requests for permission to reproduce material from this work should be sent to Permissions, University of Texas Press, P.O. Box 7819, Austin, TX 78713-7819.

LIBRARY OF CONGRESS CATALOGING-IN-PUBLICATION DATA

Francaviglia, Richard V.

    The cast iron forest : a natural and cultural history of the North American Cross Timbers / Richard V. Francaviglia.—1st ed.

        p. cm. — (Corrie Herring Hooks series ; no. 43)

    Includes bibliographical references and index.

    ISBN 0-292-72515-9 (cl. : alk. paper) — ISBN 0-292-72516-7 (pbk. : alk. paper)

    1. Natural history—Cross Timbers (Okla. and Tex.)   2. Human ecology—Cross Timbers (Okla. and Tex.)   3. Cross Timbers (Okla. and Tex.)   I. Title.   II. Series.

QH104.5.C74 F73 2000

508.764′5—dc21                             99-052955

ISBN 978-0-292-75638-0 (e-book)

ISBN 9780292756380 (individual e-book)

Dedicated to my parents,

Faye Riffin and Vic Riffin,

who recognized and encouraged my early interest in natural history.

CONTENTS

ACKNOWLEDGMENTS

INTRODUCTION

CHAPTER 1

THE NATURAL CURIOSITIES OF THE COUNTRY

A BRIEF NATURAL HISTORY OF THE CROSS TIMBERS

CHAPTER 2

THROUGH FORESTS OF CAST IRON

THE EUROPEAN AMERICAN ENCOUNTER WITH THE CROSS TIMBERS

CHAPTER 3

THE DESTROYING AXE OF THE PIONEER

THE TRANSFORMATION OF THE CROSS TIMBERS

CHAPTER 4

NOW WE HAVE THE MODERN CROSS TIMBERS

THE PERSISTENCE OF A PERCEPTUAL REGION

SUMMARY AND CONCLUSION

THE DELIGHTFUL SCENERY WE HAVE TRAVERSED

NOTES

BIBLIOGRAPHY

INDEX

ACKNOWLEDGMENTS

Many people enthusiastically helped in the research and writing of this book by generously providing information and encouragement. Folklorist Richard (Dick) Meyer of Salem, Oregon; Towana Spivey of Fort Sill, Oklahoma; historian T. Lindsay Baker of Rio Vista, Texas; artist Jane Starks of Dallas; Lea Ann Layne, city arborist of Arlington, Texas; Phil Huey of Cleburne, Texas; James Steely of the Texas Historical Commission in Austin; David Diamond, University of Missouri; Eric White, Special Collections, Bridwell Library, Southern Methodist University, Dallas; Ben Huseman, curator of the Amon Carter Museum in Fort Worth, and Ron Tyler of the Texas State Historical Association; Kevin and Cheryl Vogel, Valley House Gallery, Dallas; Wayne Clark, Mike Griswold, and Suzanne Tuttle of the Fort Worth Nature Center; David Jackson and John Crain, Summerlee Foundation of Dallas; David Riskind, Texas Parks and Wildlife; Judge Paul Pressler of Houston, Texas; historian Ty Cashion of Huntsville, Texas; Ben Scott of Arlington, Texas; Larry Schaapreld, Texas Forest Service; Michael Porter, Chuck Coffey, Charlie Griffith, and Russell Stevens of the Noble Foundation, Ardmore, Oklahoma; Ed Barron, Texas Forest Service, College Station; and Barney Lipscomb, Botanic Research Institute of Texas, Fort Worth; Jim Windier and Tom Blagg of Maguire Thomas Partners, Roanoke, Texas, provided helpful information on the Solana site near South Lake; David W. Stahle, University of Arkansas at Fayetteville; Joe Todd, Chester Cowen, and the staff at the Oklahoma Historical Society in Oklahoma City; the staff at the University of Oklahoma Library were especially helpful in providing historical photographs. Geographers Douglas A. Hurt, Blake Gumprecht, and Bruce Hoagland of the University of Oklahoma shared their interest in the Cross Timbers after learning of this book at the Southwestern Association of American Geographers meeting in Baton Rouge, Louisiana. At the University of Texas at Austin, Linda Peterson, of the Center for American History, and Richard Oram and Steve Lawson, of the Harry Ransom Humanities Research Center were very helpful in providing photographs.

At my university—The University of Texas at Arlington—I received special assistance and encouragement from library staff members Ann Kelley, Jane Boley, Betty Wood, Sally Gross, and Katherine Kit Goodwin; at the Center for Greater Southwestern Studies and the History of Cartography, graduate research assistant Jimmy Bryan did an admirable job of compiling tables of census statistics on the population and economy of Cross Timbers counties; and administrative secretaries Darlene McAllister and Lois Lettini deserve special mention for typing numerous drafts of the manuscript. Joel Quintans, production manager of UTA Publications Office, assisted in drafting several of the maps; philosophy professor Julia Dyson recommended studies of oak trees in classical literature, and history professor Don Kyle provided assistance in translating Homer’s references to oak trees. Similarly, geology professors Donald Reaser and Burk Burkhart helped by reviewing the geology and soils sections of the manuscript. Biology professor Robert Neill was especially helpful in recommending articles about the natural history of the Cross Timbers. Several students, including Bill Wilson and Alta Vick, were enthusiastic about the Cross Timbers’ role in Texas history and wrote reports on maps of the region in my cartographic history courses. Two esteemed colleagues—Gerald Saxon of University of Texas at Arlington’s Special Collections and David Buisseret, the Jenkins and Virginia Garrett Endowed Chair in Southwestern Studies and the History of Cartography—helped by reading the manuscript and offering suggestions for its improvement. To these and others not named I express my sincere thanks for help with this book.

THE CAST IRON FOREST

. . . They stood like oaks which lift up their crowns in the mountains, and day upon day resist the wind and rain, perpetually gripping the ground with their mighty roots

HOMER, The Iliad

INTRODUCTION

In his travels to the western frontier in the early 1830s, American writer Washington Irving characterized the Cross Timbers as forests of cast iron. Irving used this colorful metaphor to emphasize the toughness of the vegetation that he encountered–a nearly impenetrable forest of stunted oak trees. We now recognize that the unique forest that Irving experienced was actually vast in extent and covered portions of what would later become three states. Seen on a satellite photo, the Cross Timbers run in a generally north-south direction across a large area that includes portions of southern Kansas, eastern Oklahoma, and north central Texas. Although they do not compose a single forest, but a complex mosaic of forests interspersed with prairies, the Cross Timbers constitute an impressive geographical feature.

In this book I shall build further on Irving’s apt cast iron metaphor, which has meaning far deeper than even he might have imagined. If cast iron owes its character to the ore that is wrested from the earth, forged by heat, and quenched by cold, then the trees of the Cross Timbers themselves may be seen in light of both the geological and climatic forces that shaped them–namely, the ancient iron-rich rocks through which their roots search for water and nutrients, and the extreme climate that molds the shapes of their tortured trunks and limbs.

More than a century after Irving wrote of the region, ecologists confirmed that the distinctive trees of the Cross Timbers are well adapted to the scorching, sometimes droughty summers and to the occasional, bitter winter cold snaps that are a fact of life in this part of the south central United States. In their remarkable ability to endure in the face of rapid human settlement in the late twentieth century, the Cross Timbers are almost as durable as Irving’s metaphorical cast iron. Even in areas of suburban growth around Fort Worth and Arlington, Texas, remnants of the eastern Cross Timbers have survived as shade and ornamental trees. As a testimony to the endurance of this unique habitat, the name Cross Timbers has now become popular for businesses and other enterprises in the area.

As I will make evident, the Cross Timbers have a rich history in relation to human exploration and settlement. Existing at both the margins of the western prairies, and the forested woodlands of eastern North America (FIG. 1), the Cross Timbers compose a unique ecological zone that, in human terms, has provided habitat and sustenance on the one hand and has served as a reminder of the harshness of the environment on the other. Like many before and after him, Washington Irving was ambivalent about the Cross Timbers. He recognized that they could provide fuel and shelter, but he also cursed their resilient, unyielding countenance. Given Irving’s early experiences with the bountiful—and more easily traversed—forests of his native New York State, his ambivalence was understandable.

FIG. 1. A generalized map of the Cross Timbers region of North America, which stretches about 350 miles in a roughly north-south direction and occupies portions of three states—Texas, Oklahoma, and Kansas. Map by author based in part on Kuchler’s map in The National Atlas (1970).

In retrospect, Irving’s ambivalence was also prophetic, for the Cross Timbers were often spurned in the mid-nineteenth century for the more attractive prairie-and-oak openings. Although the Cross Timbers would help sustain hunters and settlers, most of those who settled in the area actually sought the forests’ edges, the oak-savannah ecotones that were a mixture of prairies and trees, and which provided a variety of both open and closed landscapes. The Cross Timbers in some sense thus represented the least desirable aspects of forests: they impeded one’s travels and, at the same time, offered relatively few rewards.

My first exposure to the Cross Timbers occurred in the mid-1950s, while on a transcontinental road trip that took my family across Texas. Even at twelve years old, I marveled at the changing landscapes we traversed. Like Irving, my first experience with forests had been in the lush, mesophytic woodlands of New York State, and so I judged all forests by that standard. As our automobile rushed westward through east Texas, trees seemed to become fewer and smaller in the vicinity of Dallas–Fort Worth. We had reached the magnificent open prairies, those sweeping, open seas of grass punctuated here and there by a tree, or a few trees, that stood out as if islands. In our rush westward into the prairies, however, we also traversed two narrow but distinctive belts of trees that at first seemed little more than scrubby second-growth forests. And yet, a closer look suggested that many of these trees were not young, cutover growth at all, but rather mature trees that had been stunted. Their twisted and gnarled trunks conveyed a sense of age, and their height—perhaps only thirty feet at best—implied the hardship that results from tribulation. They reminded me of the scrub oaks that somehow managed to grow on the poorest, sandiest soils of Long Island, New York, where little other tree growth could be sustained. I would indeed learn years later that two of the common oaks of the Cross Timbers, the post oak and blackjack oak, are native to and found on sandy soils from southern New England and Long Island all the way to the Cross Timbers at the edge of the great American West.

Like other westbound travelers through Texas, we soon crossed through these dwarfed forests, which were, in effect, the last flatland forests that we would encounter until reaching the Pacific coast some 1,500 miles farther west. We discovered what ecologists and geographers have known for more than a century: that these wooded areas—the Cross Timbers—represent the last of the forests as one crosses the continent from east to west. The Cross Timbers thus provide a glimpse of the ecological challenge that all vegetation faces at the margins of the great American West and Southwest. West of the Cross Timbers, in fact, forests are found only in the riparian river valleys or in the more well-watered mountains.

More than 40 years after first experiencing the Cross Timbers, I moved to this very region of Texas, and I wanted to learn more about it. In fact, my forested backyard in Arlington represents remnants of the Cross Timbers, and I found myself following that wonderful advice given by naturalists: to really understand nature, start in your own backyard and work outward from there. In addition to observing the Cross Timbers hereabouts, I read widely into the subject. Over the years I had encountered a rich but somewhat scattered literature on the Cross Timbers, of which Edward Everett Dale’s The Cross Timbers: Memories of a North Texas Boyhood (1966) remains a personal favorite since I first read it in 1970. Carolyn Foreman’s The Cross Timbers (1947), long out of print, provided an excellent guide to the historic literature but did not emphasize the region’s ecology. After an extensive search of the literature, I soon found that relatively little had been published on the Cross Timbers’ natural history in relation to human settlement. After collecting files of information about the region’s history and ecology, I set about writing The Cast Iron Forest in hopes of telling the story of this unique region of North America. I have attempted to include those numerous writers who commented upon the region in published works, some popular, some obscure. It should be noted from the outset that some of the early writers called the region The Cross Timber, which implies singularity, while later writers, myself included, use the term Cross Timbers. This more or less plural usage corresponds to our understanding of the region not as one solid forest, but rather as a series of forested areas that coexist with the prairies. Yet I use the term Cast Iron Forest as a title in recognition of the region’s singularity among American regions.

Although The Cast Iron Forest is, to my knowledge, the first book to be published about the region’s unique natural environment—and that environment’s relationship to the human experience of settlement—it builds upon a rich literature. Much of what I write here is based not only on several years’ fieldwork, but also on several excellent studies of the area’s vegetation, history, folklore, and geography that are cited throughout. It also builds upon a group of unpublished but fascinating studies, many of them master’s theses or doctoral dissertations, completed at universities over the years.

A word is in order about the term natural history in this book’s subtitle. By it, I mean a basic treatise on some aspect of nature (especially the natural development of something, as the dictionary defines it). But I also use another time-honored definition of natural history: the study of natural objects, especially in the field, from an amateur or popular point of view, as the dictionary also defines the term. Because I have a deep respect for the history of science, wherever possible I have used original descriptions and illustrations to help tell the story of the Cross Timbers. On occasion, those materials do not agree with what we know today; that is what makes them so delightful, for they reflect the limitations in knowledge at any particular time. Overall, however, I have been impressed by how cumulative our knowledge of the region has been, and so I use even the speculative materials to show that the Cross Timbers are a changing geographical, scientific, and cultural frontier. Because this book is both a natural and a cultural history, by definition it must also treat the changing human perceptions of the region.

As a historian and geographer, I have also made use of another type of primary source documentation that has rarely been used in relation to the Cross Timbers—namely the many historic maps that for more than two centuries have depicted the Cross Timbers forest as a distinctive part of the region’s geography. In doing so, I build upon Charles Oliver May’s ambitious 1962 geography thesis—the first cartographic study of the region. In addition to cartographic materials, many other written records, such as journals, diaries, and historic reports, also help tell the story of the Cross Timbers. We shall see that no two cartographers have agreed on the exact distribution of the Cross Timbers. Even the map used in this introduction—based on biogeographer A. W. Kuchler’s approximation of when the forest existed—is controversial. That very divergence of opinion about the Cross Timbers, while frustrating, adds to their mystery.

In addition to consulting several hundred maps of the Cross Timbers, I used the landscape itself for clues to determine the character and distribution of the forest. As a geographer, I have also studied the Cross Timbers in the field and from the air, observing first-hand the relationship between its vegetation and the region’s geology and settlement. The general lack of existing photographs of the Cross Timbers (likely due to the fact that the area is not especially photogenic—certainly not as much so as the Texas Hill Country, or Palo Duro Canyon, or Oklahoma’s mountainous Kiamichi Backwoods country) required me to photograph them extensively in all seasons. Capturing it on film made me ever more aware of the region’s subtle but neglected beauty. Surprisingly, this book also appears to be the first published work to include extensive photographic coverage of the Cross Timbers. I hope that the results of my efforts—this book entitled The Cast Iron Forest in recognition of Washington Irving’s encounter with the region more than a century and a half ago—conveys my sense of wonder about the Cross Timbers. I hope, too, that it convinces the reader that the Cross Timbers are a fascinating and significant part of North America’s natural and cultural history.

CHAPTER 1

The Natural Curiosities of the Country

A BRIEF NATURAL HISTORY OF THE CROSS TIMBERS

The Cross Timber of Northern Texas, which may be deemed one of the natural curiosities of the country, forms a remarkable feature in its topography.

—WILLIAM KENNEDY, Texas: The Rise, Progress, and Prospects of the Republic of Texas, 1841

The Cross Timbers of the south central United States are a forested archipelago largely surrounded by a sea of prairie. Centered roughly between the 97th and 98th meridians, the Cross Timbers vegetation comprises generally north-south trending belts of scrubby oak trees. As suggested by William Kennedy’s use of the singular Cross Timber, the distinctive vegetation is distributed throughout the region in what, to many observers, appeared to be a single line. It was this distribution, as well as the character of the forested areas, that earned the Cross Timbers a reputation as a natural wonder in the nineteenth century. Even today, the Cross Timbers typically appears as dense stands of post oak and blackjack oak trees that rarely exceed about thirty feet in height, but that are visible for a considerable distance across the prairie (FIG. 1-1). In many places, the forest is dense and the crowns of the trees not only touch, but intermingle. The relatively even height of these oak trees makes clear the lay of the land beneath them, a land that is often gently rolling. In his classic description of the region, William Kennedy’s mention of topography in the same sentence as Cross Timber would prove prophetic, for geologists half a century later would confirm the intimate relationship between the forests of the Cross Timbers and the region’s geology.

In the mid-nineteenth century, the term Cross Timber, or more often Cross Timbers, referred to a large area that consisted of a swath of trees stretching north of Waco along the Brazos River of Texas and extending far north into Indian Territory, present-day Oklahoma. Like other naturalists of this era, Dr. Ferdinand Roemer was concerned not only with the character of the vegetation but also its distribution. His 1849 Topographisch-geognostische Karte von Texas (Topographic and Geological Map of Texas) illustrates the Cross Timbers by using stylized symbols for trees (FIG. 1-2). Roemer’s map is based on the 1845 New and Correct Map of Texas by T. D. Wilson, and it clearly shows the Cross Timbers occupying a large section of north central Texas and the adjacent Indian Territory across the Red River. In keeping with the Cross Timbers’ landmark status at that time, Roemer shows them running through the Grosse Westliche Prairien (Great Western Prairie). A careful study of Roemer’s map and its predecessors reveals the use of several symbols for trees in the Cross Timbers: in the map’s southern portion, Roemer depicts what appear to be oaks almost exclusively, while in the vicinity of the Trinity River and northward into Indian Territory, he also uses stylized pine tree symbols, which likely represent cedars. Roemer’s map therefore indicates that the Cross Timbers did not consist entirely of oak trees, but also other types of vegetation intermixed with the oaks.¹

FIG. 1-1. As seen from the adjacent prairie, the Cross Timbers form a forested archipelago in a sea of grass. View near Marietta, Love County, Oklahoma (1997 photo by author).

In 1872, the well-traveled artist-writer Miner K. Kellogg traversed the prairie-forest region of the Indian Territory and Texas as part of the Texas Land and Copper Association expedition. With the eye of an artist, Kellogg observed that the traveler on the prairie beholds almost treeless country as far as the eye can reach, but that in the misty distances appears a magnificent river winding through the grandest valley ever beheld. Yet this, according to Kellogg, is not a river—it is only the effect of the differences of color between the light green of the prairie grass and the darker lines of forests surrounding them.² Although the Cross Timbers appeared as a belt (or river) of forested land in some places, it was much less pronounced in many others. As Kellogg himself observed, If we ever camped on picturesque spots I could exercise the [paint] brush—but all is monotony—Some green plains—& scrub oak parks alternately—[but] nothing to force a tired out man from reposing.³ Kellogg’s description suggests that the Cross Timbers were less pronounced in some places than in others, but that the contrast between forest and prairie was nevertheless a visually defining aspect of the countryside.

Kellogg was not the first observer to traverse the Cross Timbers: natural historians and others had already been exploring there since the 1820s. By the time Roemer published his observations on Texas (1849), the Cross Timbers area of the state had become well known to naturalists seeking to explain the unique flora and fauna. With increases in knowledge, a clearer picture of the Cross Timbers’ vegetation pattern began to emerge. From naturalists’ writings this increasingly refined understanding of the Cross Timbers’ size and character becomes apparent. In 1855, the self-trained naturalist Dr. Gideon Lincecum wrote a letter to Dr. W. Spillman of Columbus, Mississippi, characterizing the region north of Marble Falls as

[T]he country that was originally called the cross timbers. This is a stripe of timber mostly post oak and cedar, lying nearly N.E. and S.W. and is in width from 30 to 40 miles. This has no lime, but abounds in Silex, Silecious clay, magnesia, iron, alum, some coal, various other minerals, and whole forrests [sic] in petrification.⁴

FIG. 1-2. Ferdinand Roemer’s topographic and geological map of Texas (1849) uses the name Cross Tim[b]ers as well as stylized tree symbols extending from Texas into the great Western prairie of Indian Territory (Courtesy Special Collections Division, The University of Texas at Arlington Libraries).

FIG. 1-3. A cross section of the geology on a traverse along the Texas and Pacific Railroad from east Texas to west-central Texas reveals the Cross Timbers’affinity for sedimentary sandstone rocks of varying geological ages. (Source Robert T. Hill, The Topography and Geology of the Cross Timbers, 1887; courtesy the Frank E. Lozo, Jr., Center for Cretaceous Stratigraphic Studies, The University of Texas at Arlington).

Lincecum noted that this area of central Texas is part of a topographically elevated area that is rough and broken, adding that its rises are called mountains; well, they are little mountains, having the appearance of potato hills in the distance.⁵ Lincecum’s comment that this area was originally called the cross timbers indicated that he recognized it as something different—similar to, but not truly part of, the actual Cross Timbers, which lay farther north. This landscape described by Lincecum as a stripe of timber was associated with sandstone substrate—a condition that characterized the Cross Timbers proper, but could be found in scattered locations elsewhere. The presence of those cedar trees, too, suggested that limestone lay nearby, and this fact was confirmed by Lincecum later in the description. Thus, naturalists determined the close relationship between the vegetation and the geology of this region by the mid-nineteenth century. They were responsible for giving a more careful (that is scientific) definition to the Cross Timbers—a term that had been widely used by the public for almost any oak-forested land in the mid-1800s.

It was the geologists, in fact, who would help delineate the Cross Timbers as a distinctive natural region. More than a century ago, Texas geologist Robert T. Hill noted, The traveler, in crossing this region of Texas from east to west, along the line of the Texas and Pacific railroad, views the Cross Timbers merely as a grateful relief to the monotony of the prairies, and sees little in them worth remembering. However, Hill went on to suggest that, to more careful observers, the Cross Timbers has numerous points of interest bearing on their topographic and geologic relations. To clarify, Hill drew a longitudinal transect (FIG. 1-3) along the Texas and Pacific railroad line, revealing the surprisingly close correlation among geology, topography, and vegetation.⁶ It was through detailed studies of the topography that a peculiarity of the Cross Timbers in Texas—the fact that they comprised two separate belts of forest separated by a large prairie—came to be understood. Because the eastern belt was on lower-lying land, it came to be called the Lower Cross Timbers, while the more elevated forest to the west was called the Upper Cross Timbers.

GEOLOGIC SECTION ALONG THE LINE OF THE TEXAS AND PACIFIC RAILWAY, FROM ELMO, KAUFMAN COUNTY, TO MILLSAP, PARKER COUNTY.

1. Terrel; 2. Dallas; 3. Eagle Ford; 4. Arlington; 5. Handley; 6. Fort Worth; 7. Ben Brook; 8. Weatherford; 9. Millsap.

A. Coast Plain—Marine Tertiary. B. Black Waxy Prairie—Riply and Rotten Limestone, of Gulf Series. C. Eagle Ford Shales, and accompanying prairies. D. Lower Cross Timbers—Timber Creek Group (Dakota sandstone? of Shumard). E. Grand Prairie Region—Comanche (Texas) Division of the Cretaceous. e′, e″, e³, Washita, or upper, division; e⁴, e⁵, e⁶, Lower, or Fredricksburg (Comanche Peak) division. F and G. Upper Cross Timbers—f′, f″, f³, Dinosaur Sands: g, g, Carboniferous Coal-measures. Faunal horizons—e⁸, Toxaater elegans Fauna; e″, Horizon of Gryphæa Pitcheri (var. Dilatata) with Ostrea carinata; e³, Gryphæa Pitcheri, var. Fornicula (Exogyra fornieulata; e⁴, Ammonites vespertinus; e⁵, Hippurites (Caprina) Limestone; e⁶, Comanche Peak Fauna, including horizon of Gryphæa Pitcheri with Ostrea Matheroniana.

In delineating the Texas Cross Timbers in such detail, Hill not only consulted the literature, but relied on extensive fieldwork that would have been difficult to conduct a generation earlier. Of the many scientists drawn to Texas before 1850, most—like the famed Roemer—explored far south of the Cross Timbers. Nevertheless, the Cross Timbers were so well known by that time that Roemer and other naturalists were often obligated to make at least passing reference to them in their overall discussions of the state’s natural history. Some reports included lengthy descriptions of the Cross Timbers based on the firsthand accounts of other observers who appeared to be trustworthy sources—but who related considerable hearsay. And yet, some very significant field research occurred in the Cross Timbers as naturalists were drawn there after the mid-nineteenth century. Among these multi-disciplinary scientists was Jacob Boll, the Swiss naturalist and entomologist, whose collections in all fields of natural history in Texas are of the greatest importance.⁷ Between 1860 and 1880, Boll explored the natural history of portions of north Texas in and adjacent to the Cross Timbers; although Boll’s work does not focus on interpreting the Cross Timbers per se, his fossil collecting helped scientists better understand the relationship of the Cross Timbers’ geology to that of the surrounding country.

Indeed, the maxim that a region’s geology is essential to understanding its ecology is borne out by the Cross Timbers. It was, in fact, the Cross Timbers’ geology that drew special attention from nineteenth-century scientists—perhaps because the entrepreneurs who supported such scrutiny were ever alert to mineral wealth in the form of ores and coal resources. An 1844 letter by Charles Elliot reveals the manner in which the Cross Timbers were eyed more than a century and a half ago not only for their vegetation but also for their potential to yield mineral resources. While traveling widely in the Texas Republic at that time, Elliot left a fairly detailed account of the Cross Timbers in a letter to his associate William Bollaert. Elliot wrote Bollaert that the Cross Timbers running through the colony in a N.E. direction, is a section or belt of timber land of a loose yellow soil covered with an undergrowth of vines, sumach [sumac], redbud, and indications of productiveness, yet the land is not so lasting as the prairie.⁸ Elliot then went on to note that every variety of oak as well as other trees could be found in the Cross Timbers. He added that iron appears in the Cross Timbers in inexhaustible quantities and also noted that deposits of stone coal could be found in large quantities near Bird’s Fort.⁹

Observers noted with much interest the relationship between iron-rich sediments and vegetation. In the Cross Timbers region, a dark brown siliceous iron ore was commonly found in the more elevated topography—the low, wooded, erosion-resistant hills and isolated knobs known as ‘ironore knobs.’¹⁰ This feature is part of the Woodbine Formation that lies just west of the Eagle Ford Shale. Deposited about 96 to 92 million years ago, the Woodbine Formation underlies the Eastern Cross Timbers. This forested strip of land lying between the Blackland Prairie to the east and the Grand Prairie to the west promised great mineral riches, notably iron and coal for industry. In retrospect, however, Elliot’s and many others’ assessment of iron in the Cross Timbers was exaggerated (though significant deposits do exist farther east in Texas). Elliot’s assessment of coal was somewhat more accurate, although the deposits are considerably west of Bird’s Fort, in the Western Cross Timbers. Despite some