Stories in Stone

by David B. Williams

  “Petrified wood is the fossil for the common man,” says Kirk Johnson, a paleobotanist at the Denver Museum of Nature and Science.2 In traveling around the American West, he has seen dozens and dozens of petrified logs in people’s yards. “Some of the specimens weigh hundreds of pounds. I am amazed at the efforts people go to to haul this stuff back home,” he says. “I think it’s because they can relate to the wood as a living organism. They can recognize it as a petrified tree.”

  I observe people making the petrified wood–living tree connection often in my part-time job as an educator at the Burke Museum of Nat ural History and Culture in Seattle. As part of the teaching program, we give the students the opportunity to handle a variety of fossils. The only fossil that every child can identify is the piece of petrified wood. The parent chaperones also are able to recognize the fossil and they get more excited by a two-inch-diameter piece of petrified wood than by a four-inch-long Tyrannosaurus rex tooth. No one can walk out of a museum and immediately see a dinosaur, whereas a museum visitor can walk outside and immediately encounter a living tree that looks identical to the 100-million-year-old fossil tree she just encountered.

  Recognition also applies in nonmuseum settings. Most fossils one encounters in the field don’t look like a distinct life form (and definitely not like they do in a museum) or if they do look somewhat recognizable, few people can identify the specimen beyond calling it a bone or a shell. In contrast, when someone finds petrified wood in the field, they are often able to recognize it as a fossilized tree and not merely a fossilized something or another. They can have a distinct sense of discovery, knowing they have made a connection to the past. It can be a profound moment, particularly if they have never found a fossil before.

  Petrified wood has another advantage over most other fossils. Drop that T. rex tooth and it might break. Drop a piece of petrified wood and it might hurt the floor or toe it hits but it will remain intact.

  One of the most beautiful of fossils, petrified wood is displayed in photos in Frank J. Daniels’s book Petrified Wood: The World of Fossilized Wood, Cones, Ferns, and Cycads. One strange specimen from Arizona has quartz-filled cracks that look like a star in a night sky. A green and blue stump from Oregon resembles a topographic map of rivers and forests, and a fiery red, yellow, orange, and blue log from Nevada seems to glow from within. On many of Daniels’s examples, the perfectly preserved annual tree rings allow you to determine precisely how long the tree lived.

  Unfortunately, people’s fascination with petrified wood often motivates them to break the law. Rangers at Petrified Forest National Park in Arizona estimate that visitors steal twenty-four thousand pounds of petrified wood per year. Many scofflaws argue that they don’t know they are breaking the law, despite the numerous signs telling them otherwise. Some think that if they don’t pick up the petrified wood, it will erode and be lost to science—still others take a more modern approach and blame their parents, claiming that it is family tradition to collect petrified wood.3

  About a mile from the exits, rangers erected signs warning that cars are subject to inspection before leaving the park. The warning has had limited success, as each month, park employees collect just tens of pounds of petrified wood near the signs.

  The park visitor center has a display of what rangers call “conscience letters” from people who were not caught during car inspections but who later returned their purloined petrified wood. Many letters refer to a curse. People said they lost their dogs, got flat tires, or had a death in the family because they had taken a piece of petrified wood. The display has been effective; follow-up interviews by park employees show that 80 percent of people who read the letters said they wouldn’t steal wood— not because it was illegal but because of the potential bad luck. One unexpected consequence, however, was that visitors who read the letters sometimes stole a piece so they could send it back with a “witty letter,” in the hopes it would get posted in the park’s display. The park receives about six hundred pounds of returned petrified wood per year. Clearly the curse is only so effective.

  Fossils such as petrified wood have long intrigued people. “No greater objects of wonder have presented themselves to man’s consideration than the fossils which from earliest times have been observed in different parts of the earth’s crust,” wrote Lester Ward in his Sketch of Paleobotany.4 And yet few understood how fossils formed until at least the late 1800s. Prescientific ideas fall into three camps: by magic, by seed, and by flood. Many early natural philosophers did not consider fossils as the remains of once living beings. Instead fossils were lusus naturae, freaks of nature, which some latent planetary force (vis plastica) mystically created. One sixteenth-century writer, George Agricola, attributed petrified wood formation to a stone juice, succus lapidescens.

  The second camp was only slightly less mystical. In 1699 Welsh naturalist Edward Lhuyd described “exhalations which are raised out of the sea” carrying fish-spawn that got caught in chinks in the ground and became fish fossils, which “have so much excited our admiration, and indeed baffled our reasoning.”5 Lhuyd may not have had a clue about how fossils formed, but he has recently received credit for the earliest description of a dinosaur fossil. He, however, thought the dinosaur tooth was one of his vapor-produced, fauxfish teeth.6

  In the best case of a religious reformer masquerading as a scientist, Martin Luther popularized the idea that fossil plants and animals developed from Noah’s flood. He wrote in his Lectures on Genesis in 1535, “I have no doubt that there are remains of the Flood, because where there are now mines, there are commonly found pieces of petrified wood.”7 Although Luther’s diluvial theory took nearly a century to gain popularity, it influenced many scientists of the seventeenth and eighteenth centuries, particularly Swiss paleobotanist Johann Scheuchzer, who reported that he had found the fossilized remains of an eyewitness to Noah’s big adventure. For those interested in seeing the infamous skeleton, named by Scheuchzer Homo diluvii testis, or human who witnessed the deluge, all you have to do is travel to Teylers Museum in the Netherlands, where you will learn that Scheuchzer’s eyewitness was a giant salamander.

  “This view [Luther’s] may seem to us a poor substitute even for the worthless dreams which had to make way for it, but when philosophically viewed it will be seen that it was really a decided advance upon these,” wrote Ward.8 Diluvialists may have been completely wrong about the Flood, but at least they acknowledged that fossils developed from formerly living plants and animals that had turned to stone after the mud from the Flood covered those who missed the boat.

  These early writers suffered because all of them lived before anyone had a remotely accurate age for Earth. An origin in Noah’s flood made sense in their minds because the planet was only six thousand years old and the only widely accepted big event that could have killed and preserved so many plants and animals was the deluge. Not until the 1800s did fossil collectors consider a time on Earth before the Flood and before Adam and Eve. Aided by the work of Lyell and Darwin, paleontologists (the term first appeared around 1830) began to recognize that different plants and animals lived and died at different times in the past. By 1885, when Ward penned his Sketch, he could confidently reject the “puerile speculations” of old and rejoice in the “true advent of science.”

  After recognizing the great age of fossils, paleontologists turned to another hallowed question pondered over the millennia by fossil enthusiasts. How did petrified wood form? Agricola’s idea of a stone juice penetrating rocks and producing something that looks like bone or wood may sound a bit too mystical but he was on the right track; petrified wood requires mineral-rich groundwater in order to form. First, the tree must get buried rapidly to prevent oxygen from reaching the wood. Otherwise, fungi consume the wood. Burial that leads to wood preservation may occur via volcanic ash, which can preserve trees upright, or via fluvially deposited mud, which can bury trees transported downriver.

  Next, a petrifying agent must enter the wood. At le
ast forty different minerals have petrified wood, but the most common by far is quartz, or silica. Because quartz resists chemical and physical breakdown better than most other minerals, any tree petrified by silica usually lasts longer than one preserved by calcite or pyrite, the next two most common minerals to petrify. Other trace amounts of elements may also invade the wood and provide color, such as iron (red), manganese (blue to purple), copper (green), and sulfur (yellow).9

  A lack of oxygen does not mean a lack of life. Bacteria in the wood aid the process of silification by creating acidic conditions that lead to silica precipitating out of the water. The silica accumulates on and in the wood’s cell walls, which act as a template for growth. Petrifaction continues as the woody walls deteriorate and more silica fills the voids, faithfully replicating the tree’s internal structure. This process of per-mineralization commonly occurs in the fossilization of many organisms.

  The change from wood to stone straddles a fine line between deterioration and accumulation. The wood has to break down slowly enough to allow silica to penetrate and replicate the plant’s cell structure. If deterioration occurs too quickly, the template will disappear and no structure will remain. If it occurs too slowly, no voids will form for silica accumulation. “Organic templating,” as geologists call this mode of preservation, contrasts with a common misconception that silica simply replaces wood molecule by molecule. In fact, most petrified wood still contains organic material, up to 5 percent by weight.10

  Experimental research has shown that petrifaction can occur very quickly. A German physician wrote in the sixteenth century that he had made wood as hard as flint in three years by cooking it in beer and burying it in his cellar. Modern researchers have also placed alder wood in hot springs and within seven years silica had permeated the wood. Perhaps if Martin Luther had conjectured that Noah had floated on a sea of hot beer, then we might believe the German theologian’s geologic observations.

  Geologists reject a young age because of the instability of the silica that impregnates wood. Under a microscope, quartz can look either ordered and crystalline, known as agate or chalcedony, or amorphous and watery, known as opal. The majority of petrified wood under 65 million years old is opal, whereas older petrified wood is chalcedony. Researchers account for this difference because heat drives off water, consolidates the internal structure of silica, and converts opal to agate, a process that normally takes millions of years. Beauty comes to those who wait.

  Bill Brown was not unusual in using nearby stone for building. A lack of money and lack of good means of transportation often drove the decision to go local. Driving across country in 1996 through western Kansas, I remember being struck by the sight of a sign welcoming us to Post Rock country. After wondering if we had entered some midwestern enclave of Yanni fans, I started noticing that fence posts along Interstate 70 were made from stone and not from wood. Turns out that in a land of few trees and many cattle, the best way to build a fence was to use the local limestone, a yellow-tan rock easily quarried from just below the surface. The post rock era ended in the 1920s, when farmers and ranchers began to use wood and steel, transported by railroads and cars.

  In cities, one of the easiest ways to find older local stones is to look for big building blocks. Prior to the popularization of steel infrastructures in the 1890s, builders relied on stone for structural support, which required building blocks large enough to withstand the weight of tall structures. Style could also dictate the use of massive blocks, particularly during the era of Richardsonian Romanesque architecture and its emphasis on a natural, rough-hewn look for building materials. Architectural preference can complicate the picture during this period, the last quarter of the 1800s, but many who chose big blocks based on Richardsonian principles still had to use what was nearby because of shipping costs. For the most part large equals local.

  I often take advantage of these early builders’ reliance on local rock to impress my friends when I travel. All I have to do is find the oldest stone buildings and I can get an insight into the local geology and have fascinating stories to tell. (Of course, I could be misinterpreting my friends’ comments, such as “That’s great,David. Why don’t you go do some more research on that and find us later?”) Using this trick is particularly slick in urban settings, where most geology is long removed or long covered by development. For example, in downtown Seattle, which lacks any visible surface exposures of rock, most of the old stone buildings were constructed with sandstone, which points to sediment-rich rivers as a former dominant regional environment.

  Others have used local buildings to learn more about local geology. In the 1890s, while searching for fossils about ten miles east of Medicine Bow, Wyoming, paleontologist Walter Granger chanced upon the remains of a cabin. To Granger’s surprise the sheepherder who built the cabin had used fossilized dinosaur bones for the little building’s foundation. As he looked around, Granger realized that dinosaur bones covered the hillside. A year later he returned with a crew from the American Museum of Natural History (AMNH) and eventually dug up the bones of sixty-four dinosaurs, including Allosaurus, Apatosaurus, Diplodocus, and Stegosaurus. The AMNH men worked the Bone Cabin Quarry for six years and transported over 150,000 pounds of bone back to New York, making the hillside one of richest discoveries of dinosaurs ever.11

  The Wyoming sheepherder and others who incorporated local stone did so for practical reasons. In the 1920s and 1930s, however, builders started to incorporate unusual local rock for a different purpose, to attract that new breed of American, the motor tourist. Even in small towns, stone no longer had to be local; railroads could transport exotic rock to within reach of anyone who desired it, but some business operators recognized that they could use their local stone to differentiate themselves from their competition.

  For seventeen years, Thomas Boylan had collected dinosaur fossils from the hills around his home, about six miles due south of the Bone Cabin Quarry. He had intended to assemble them into a complete skeleton, but when he consulted local paleontologists, Boylan learned he had collected bones from a hodgepodge of species, “so I abandoned the idea and proceeded to use them the best way I could,” he once told a reporter. In 1932 Boylan decided to draw attention to a gas station he ran by erecting a twenty-nine-foot by nineteen-foot building, which he built by cementing together the 5,796 bones he had scavenged. He referred to it as the Como Bluff Dinosaurium and the Building That Used to Walk. Boylan, and later his widow, ran the gas station and dinosaur cabin, which they converted into a museum, until the 1960s, when Interstate 80 replaced Highway 30 as a major thoroughfare through Wyoming.

  Boylan and Brown also promoted their enterprises by printing postcards. Both attracted the attention of Robert Ripley, who featured the buildings in his Believe It or Not column. Brown’s card shows his station with no pumps, just a well-dressed woman and man. Ripley mentioned the station in his column on December 17, 1935, under the odd caption The Petrified Wood House, Built Entirely of Wood Turned to Stone.12

  Boylan’s card, labeled Petrifications on U. S. Highway 30 Como Bluff, Wyoming, shows that he spruced up the building by adding a sign describing Wonderful Wyoming the Dinosaur Graveyard. On the back, he described the “torpid reptiles” who “thrived in torrid heat” and called the building a “5796 page book of creational hieroglyphics.” Ripley highlighted the cabin in his newspaper feature on April 26, 1938, as the “Oldest” Building in the World.

  Brown’s building made it back into Ripley’s again on September 21, 1991. The new caption read, The World’s Oldest Building. (From a geologic point of view, Brown’s building is made from older fossils than Boylan’s.) To be closer to the truth, Ripley would be better off by referring to the Morton liquor store building as the “Oldest” Liquor Store in the World.

  These stone structures exemplify a change in America that had started slowly at the turn of the century and by the 1920s was rippling through the country. It was a change based on new technology and a new natural res
ource, fostered by the relief of winning a world war, and propelled by a rising stock market. The change was quintessentially American. Or as James Agee put it in Fortune magazine in 1934, “So God made the American restive. The American in turn and in due time got into the automobile and found it good.”13

  In 1910 only five hundred thousand people owned automobiles, in part because nearly all of the country’s lanes, paths, and thoroughfares began as routes for animal-powered vehicles, which were superior to gasoline-powered vehicles at negotiating ruts,mud, and washouts. With the addition of new road surfaces oriented toward cars, such as asphalt and macadam (invented by Scotsman John McAdam), restive Americans were now able to go forth and drive, traveling on roadways with names such as the Lincoln Highway, Black and Yellow Trail, Old National Pike, and Lone Star Route.14 By 1920 over 8 million people had registered their cars; by 1927,15 a Model T cost $385; and by 1929, every state had established gas taxes to pay for roads.16

  America had long been a nation of transients and travelers. We liked to move and when trains came along we hopped on them and went, but the automobile offered several significant advantages. Motorists controlled their own destiny and didn’t have to rely on someone else’s schedule or someone else’s limited routes and limited stops. A family traveling in a car could stop where and when they wanted. Plus they traveled at a more human speed, not the blur-inducing, scenery-bypassing rate of a roaring locomotive. “More reliable and powerful than a horse, more personal and approachable than a train, the automobile seemed to restore a human scale to machinery that had been lost with the onset of the steel age,” wrote Warren Belasco in Americans on the Road.17