Wednesday, March 25, 2009

Cambrian Life in Wisconsin

As I have noted earlier in regard to the footprints in Mexico and the basalt in India, quarries often open up windows into stone that help geologists better understand the world. One of those revelatory quarries is found in Wisconsin, about 200 miles northwest of Milwaukee, where paleontologists found a beach-load of jellyfishes that died 510 million years ago. Each jellyfish resembles an aerial shot of a crater with a slightly raised center, the bell of a jellyfish, surrounded by a concave ring that ends in a prominent rim. The biggest are up to 70 centimeters in diameter.

Fossils from Wisconsin. Fossil D=70cm. From Geology Feb. 2002.

Fossil dealer Dan Damrow discovered the jellyfish in 1998 and four years later co-wrote an article (Geology, February 2002) describing the animals with paleontologist James Hagadorn. Technically known as medusae, the jellyfish were pelagic carnivores that moved into the littoral zone to hunt but a receding tide could trap the animals in great masses on the beach. As the tide ebbed and returned, fine-grained sediment covered the jellyfish, preserving the rarely preserved soft tissues. Ripple marks surround and in a few cases pass through the fossils. Damrow and Hagadorn report that the fossils were found in seven, flat-lying beds, which covered perhaps a million years of time, and that they provide new insights into the Cambrian.

The Krukowski family own the quarries and sell the fossiliferous rock under the trade names Highland Brown Antique, Sandy Creek and a sawn version called Cambrian Cream. Uses include architectural veneer stone, thin veneers, outcropping, steps, flagstone, and landscape retaining walls. The sawn version is transferred into countertop slabs, cladding, flooring and a variety of architectural and landscaping products. Because no one had recognized the fossils until the Damrow saw them, many people could have the fossils in their homes without knowing it.

Climactichnites (from Wikipedia)
Paleontologists have also found another unusual fossil at the Krukowski site. Known as Climactichnites, the fossils resemble tire tracks and have been described as both trace fossils and body impressions of a gelatinous zooplankter. More recently, a graduate student of Hagadorn’s has reexamined the traces from Wisconsin and other sites, and interpreted them as gastropod tracks, possibly from some of the earliest terrestrial animals. Apparently life in the Cambrian in what became Wisconsin was rather interesting.

Saturday, March 21, 2009

Overlooked but not Forgotten

Many people, including me, have written extensively about the famous white limestone from Indiana. In my book Stories in Stone, I call the Salem Limestone, “America’s Building Stone,” and as far as I have been able to discover, it is the only building stone used in all 50 states. Recently, however, I have learned of another white limestone often mistakenly described as Salem. Much to my pleasure, being a native of Kentucky, that other stone hails from quarries in Warren County, Kentucky, in the southwest corner of the state.

The story of the Bowling Green Oolite comes from research by Western Kentucky University geologists Mike May and Ken Kuehn. They found that the oolitic limestone was popular from the 1870s to the 1920s with the quarries shutting down around 1937. During that time it became famous for its pure white color and received a gold medal at the World's Columbian Exposition in Chicago in 1893 and the highest award at the Louisiana Purchase Exposition (St. Louis World's Fair) in 1904. A 1923 Kentucky Geological Survey Publication, written I am sure without any bias, described the Bowling Green rock as “The Aristocrat of all the limestones.”

The publication further noted one unusual aspect of the stone—petroleum “impregnated” the rock. Oil gave the rock a dingy and unpleasant color when first quarried and carved, but soon the evaporation of the occluded petroleum left behind a stone of “great whiteness and remarkable beauty.” And it goes without saying that Bowling Green Oolite had superior strength and durability.

Episcopal Church of Saint Thomas (from St. Thomas web site)

Like the Salem, the Bowling Green Oolite, formally known as the Girkin Limestone, is Mississippian in age. The Girkin is most famous as the stone where the Mammoth Caves of Kentucky formed. The stone crossed state boundaries, with structures such as the U.S. Custom’s House in Nashville, TN and the Hall of Records in Brooklyn, NY; and religious boundaries, going into Methodist, Presbyterian, Catholic, and Episcopal churches, as well as a synagogue. One of the most famous buildings is the Episcopal Church of Saint Thomas in Manhattan, finished in 1913, during the prime years for usage of white limestone from the Midwest.

I suspect that most buildings that I think of as Salem Limestone are Salem, particularly in areas in the west, but I now know that some may have been mislabeled. I look forward to finding more buildings from my home state.

Monday, March 16, 2009

Footprints in the Ash

Over the past couple of years, a controversy has arisen over possible human footprints in central Mexico. The disagreement centers on age and maker. Is the ash where the prints are preserved 40,000 or 1.3 million years old and did people out for walk produce the foot-shaped impressions or did more recent people inadvertently alter the rock and subsequent weathering and erosion form the marks? The simmering debate raises many questions but to me the focal point is the fact that the tracks occur in an abandoned building stone quarry.

Footprints in ash layers, from from web site of Sarah Metcalfe, University of Nottingham

The debate began in July 2005 when Dr. Silvia Gonzalez and her colleagues at Liverpool John Moores University reported that they had found 40,000-year-old human and animal footprints preserved in volcanic ash. The ash had fallen along a shoreline of a shallow lake in the Valsequillo Basin, about 80 miles southeast of Mexico City. If the dates are correct, it would make them the earliest evidence for people in the Americas. Gonzalez’s team based their analysis on accelerator mass spectrometry dating, electron spin resonance, Argon-Argon dating, and optically simulated luminescence dating. Knowing that the dates would be controversial, Gonzalez said at the time “It’s going to be an archaeological bomb and we’re up for a fight.”

By the end of 2005, a team at Berkeley Geochronology Center at the University of California Berkeley had responded. They reported that the ash dated to 1.3 million years old. Either the tracks belonged to our ancestor Homo erectus or, more likely, the impressions were not footprints but marks that resulted from quarrying. The California team also relied on Argon-Argon dating, as well as a paleomagnetic data. Their most recent and detailed analysis of the quarry site ash appeared in the March 2009 issue of Geology.

Numerous small quarries dot the Valsequillo Basin. The ashy layers split into thin sheets that can be used in roads and walkways. The track-rich quarry was abandoned relatively recently, according to Joshua Feinberg, formerly a graduate student at UC-Berkeley and now a professor at the University of Minnesota, but not before workers had removed several feet of lake sediments to get to the underlying hard beds of ash. As happened with the quarries examined by Gerta Keller for evidence that gases released by voluminous basalt flows led to the extinction of the dinosaurs, the Mexican quarry workers made the story possible by exposing the ash.

Quarried stone from web site of Sarah Metcalfe, University of Nottingham

“[T]he past quarrying activity really is an essential part of this story,” wrote Feinberg in an email to me. Not only did it reveal the tracks but he suggests that quarry workers left the marks in the ashy layer and that over time they eroded into shapes that Gonzalez’s team misinterpreted as human footprints. I will let the scientists duke out the when and who of the story but I do take pleasure in knowing that yet another building stone quarry makes the world a bit more interesting.

Wednesday, March 11, 2009

Good Old Cobblestones

President Obama has said that his stimulus plan will provide the “largest investment increase in our nation's infrastructure since President Eisenhower created the national highway system half a century ago.” It will create hundreds of thousands of job for people rebuilding railways, bridges, and roads. While I applaud his concern about jobs and improved safety, I worry that in the mad rush to pave we may lose a bit of history—the handful of cobblestone roads still dotting Seattle.

A happy group of explorers trodding across one of Seattle's last cobblestone streets

Between the 1890s and 1910s, sandstone cobbles were a a popular road-paving material in Seattle. The most commonly used varieties came from quarries in Wilkeson, a small town about 45 miles south of Seattle. Workers could easily cut the brick-sized blocks, which provided good traction for horses, although horse shoes did wear down the stone. And the stone cobbles lasted longer and created less of a mess than the mud or wood of the past. (Manhattan also has a few cobblestone streets made from the 450-million year old Quincy granite.)

Quincy Granite cobblestones in Greenwich Village

The Wilkeson sandstone lithified from thousands of feet of sand deposited 40 to 50 million years ago in the Eocene Period when western Washington was flat and subtropical. Palm trees, swamp cypresses, and tree-sized ferns grew in the moist (40-100 inches of rain), bayou-like environment. Waves from an ocean that spread to the west washed ashore on beachfront property, now covered by the urban metropolises along Puget Sound. The only mountains that existed rose far to the east along the Washington-Idaho border. Rivers and streams washed out of those mountains and dropped sand in a coastal lowland dotted with seasonal lakes, swamps, and lagoons.

In addition to sandstone cobbles, brick was another important paving material and can still be found on a few Seattle streets. Local manufacturers used a clay deposited in a proglacial lake, which formed in advance of the ice sheet that covered Seattle during the last Ice Age. A production capacity of 70,000,000 bricks a year made King County the largest producer of paving brick in the country. At one time, these bricks covered streets in Portland, San Francisco, Tokyo, and Los Angeles, as well as roads in Chile, Argentina, and India.

One other local building material, the Index granite, appears on local streets. It formed 34 million years ago during subduction of the Juan de Fuca plate under the North American continent. The Index was used primarily for curbs and can still be found in a few older neighborhoods of Seattle. (One way to get a feel for the age of a neighborhood is to look at the curbs. Old ones are granite; newer ones have concrete with a metal rim, particularly on corners; and modern ones are only concrete.)

According to the last official survey I could find, conducted in 1993, only 93 of these historic streets remain in Seattle; most have been paved over, their stories lost to drivers who don't want the jarring ride. I do not mind them. I like the connection to the past and consider it a privilege to drive over the ancient cobbles and rustic bricks, although I try to take these roads when no else is in the car with me.

Thursday, March 5, 2009

Building Stone Census of 1880

Every ten years the federal government conducts a census of the people. Census takers spread across the country ferreting out the vital statistics of America. For the 1880 census, the government also took stock of building stones and the quarry industry. I was recently lucky enough to acquire a copy of the 410-page report. (It came to me because my brother-in-law bought a bar in Arizona, which had the book in it, and his seven-year-old son was kind enough, with a bit of coercing, to give me the tome.)

As one might expect of a census, the book provides a minutia of facts. For example, 1,525 quarries operated and generated 115,380,133 cubic feet of stone, roughly enough to build one and a half Great Pyramids. Or you can learn that a David Williams owned a slate quarry in Slatington, Pennsylvania. The quarry was in Lower Silurian beds, produced black slate for roofing and school slates, and opened in 1864. Sounds like an industrious fellow.

Of more interest is the section that describes the building stones used in 137 cities, ranging from Akron, Ohio to Zanesville, Ohio. The listings reveal the classic story of most cities and towns, which generally use local stone, if available. Some people also import outside rock, most often for monumental buildings such as banks or churches. The story changes slightly in the bigger cities of Boston and New York, which still use local rock but also pull in stone from around the world. For example, exotic marbles came from Italy, France, Portugal, Switzerland, Spain, and Germany. That being said, 80 percent of the stone fronted houses in New York City used brownstone, most likely quarried in either Connecticut or New Jersey.

A hornblende granite from Grindstone Island in New York, some of which was used as paving material in Chicago

Reading through the census book, I am reminded of other books like this. These are the older scientific books that seemingly attempt to put in everything known about a subject. They are clearly labors of love of the writer and detail not just the science but also the history of a subject, such as the origin of a name of a species or who first used a particular building stone. In delving so deeply into the finer points, the authors make their subjects so interesting that the reader cannot help but take a deeper interest.

A channeler, used to cut stone into blocks in the quarry
Perhaps that is why my new book from 1880 survived its long life at a small bar in the middle of nowhere Arizona. I like to imagine that the drinkers of yore gathered around the book late into the evening and regaled each other with the many fine facts. I am sure they were better people because of what they learned.

Tuesday, March 3, 2009

USGS: 130 Years Old

On March 3, 1879, President Rutherford B. Hayes signed a bill in the closing hours of the 45th Congress. Packed with a variety of items, the bill also had a short item establishing the United States Geological Survey, which would have the following mandate: "classification of the public lands, and examination of the geological structure, mineral resources, and products of the national domain." Three weeks later, Hayes appointed Clarence King to be the first director of the USGS and on May 24, he became the director.
Clarence King (From USGS)
King was well known for his role in running the United States Geological Exploration of the Fortieth Parallel, as well as his exposure of the Diamond Hoax, when hucksters salted a secret field with diamonds. Investors fell for the ruse, almost ponying up millions of dollars for further exploration until King and his men revealed the nefarious ways of the charlatans. King directed the USGS for just one year, ultimately quitting in part because of his constant need for making money, the one part of his life he was not successful at.

Called by Abraham Lincoln's Secretary of State John Hay, "the best and brightest of his generation," King was a complex man, who lived a hidden life for his final 13 years. Unbeknownst to all his friends, King had secretly married Ada Copeland, a former slave. King told her that his name was James Todd and that he worked as a Pullman Porter, which by definition meant that he was a black man. King was deeply in love with her and they eventually had five children.
Little was known of King and Copeland's life until the recent publication of Martha Sandweiss's excellent book, Passing Strange: A Gilded Age Tale of Love and Deception Across the The Color Line. In it she details their years together and shows how King lived his double life. For anyone interested in one of the greatest and best known geologists of the middle 1800s, it is wonderful book. Passing Strange is also a fascinating insight into America during the Gilded Age.