Monday, December 29, 2008

Deccan Traps: A Different Take

At the recent 2008 AGU meeting in San Francisco, a long simmering controversy reared its head again.  Paleontologists Gerta Keller and Sunil Bajpai and geophysicist Vincent Courtillot presented evidence that India’s Deccan Traps, and not the Chicxlub meteor in Mexico, created the unhealthful conditions that led to the extinction of the dinosaurs.  Their data is thought provoking but what attracted my attention was Dr. Keller’s comment that much of their data came from quarries in the basalt.  

Erupted 65 million years ago, the Deccan Traps covers an area as large as Texas.  Geologists have estimated the volume at 1.2 million cubic kilometers, with nearly half lost to erosion.  The depth of the layers is more than 3,500 meters thick.  At AGU, Keller observed that the viscous basalt spewed forth in as little as 10,000 years. 

Basalt Quarry: Photo from Gerta Keller

The quarries that interest Keller and her colleagues are found in flows that oozed 800 kilometers across India to Rajahmundry, on India’s east coast.  They are the longest lava flows on Earth.  Dozens of quarries pockmark the Rajahmundry traps of the Deccan plateau.  (Trap refers to any dark colored igneous rock though it is most commonly associated with basalt; trap comes from the Swiss word for step.)  According to Dr. Keller, families and extended clans work most of the quarry sites by hand, using hammers and explosives.  Men break up the stone and women carry it out on their heads.  And in some cases, trucks transport rock to people’s homes and dump the material in their backyards, where they work on it. 


Worker at basalt quarry: Photo from Gerta Keller

Because the Rajahmundry basalt resists weathering, much of it goes for roads and to make train beds.  It is shipped to Europe and perhaps to the United States.  Basalt from other flows in India have been used as a building stone, though Dr. Keller did not know if the Rajahmundry stone had gone into buildings. 

The quarries have played an important role in Dr. Keller’s research because they expose the rocks that she has wanted to study.  In the quarries is evidence for shallow marine deposition, where marine microfossils were preserved.  These fossils have been essential to narrowing the date of Deccan Trap deposition and allowing Dr. Keller to further elaborate on her thesis. I am not qualified to say whether her theory is right or wrong, but the work raises some interesting questions and if Dr. Keller is right, you may want to give a second thought to the road you travel on.  It may contain evidence for the dinosaur’s demise.

 

 

 

Tuesday, December 23, 2008

Airport Fossils

Trapped at SeaTac Airport in Seattle with nothing to do?  I am sure the people stranded there would rather be someplace else but the extra time will allow intrepid travelers to explore the many fossils found in the walls of the food court in concourse A.  The fossils make a captivating cast of characters that lived 155 million years ago in what became Germany.  During the Jurassic Period when dinosaurs roamed the land, a shallow sea covered much of Europe.  Many critters from that sea are now preserved in the tan to gray limestone cladding walls at SeaTac. 

155-million-year old ammonite - Good examples are in the pillars just past the security check, particularly the one nearest Ex-Officio.

The stone is known as the Treuchtlingen Marble, although it is not marble but limestone.  It was never metamorphosed.  As the animals died they settled to the bottom of the sea.  The most common fossils are sponges, bottom dwelling, filter feeders that formed small mounds.  They may be round, straight, or irregularly shaped and are darker than the surrounding limestone.  Also common are ammonites, coiled-shell animals that resemble a top down view of a cinnamon roll.  The biggest ones in the German limestone are about five-inches across, whereas the largest ones that ever lived were six feet wide.  Ammonites were prevalent marine predators in the Jurassic but went extinct at the end of the Cretaceous.  Their modern relatives include squids, chambered nautiluses, and octopi.  

You can also find another squid relative, belemnites, which look like a cigar.  They are dark brown and somewhat shiny.  Also seek out brachiopods, clam-shaped animals known as lampshells due to their resemblance to ancient oil lamps.  Unlike clams, brachiopods cannot move and feed by opening their shell and consuming bits that float by.  And finally, the white specks that look like oatmeal are single-celled sea dwellers called foraminifera. I hope this at least helps some people pass the time at SeaTac.

Saturday, December 20, 2008

The Comstock King and Brownstone

“San Francisco’s crown in the matter of private architecture has rested on the brow of the city’s famous Nob Hill for the past 10 years but the brightest jewel in the setting is receiving its finishing polish,” appeared on page 4 of the May 9, 1886 New York Times.  The short article was referring to the mansion of James C. Flood, best known as one of the Nevada Comstock Kings.  His home was reportedly the most expensive private residence in America.  The reason was understandable—Flood’s 42-room estate was made of sandstone shipped around Cape Horn from Connecticut.  Total cost was $1.5 million and included a $30,000 bronze fence, which was rumored to be polished by a man whose sole job was to do so. 


Flood chose the red sandstone, better known as brownstone, because it was the stone of the wealthy.  William Vanderbilt, J.P. Morgan, and George Pullman all lived in brownstone homes, and brownstone was called an “almost proverbial synonym for all that is elegant and desirable.”  Tons and tons of brownstone was shipped as ballast around Cape Horn.  The 107 foot by 127 foot edifice featured 14 solid stone columns, 13 feet tall by 22 inches square, and 23-foot-long sandstone steps.  The biggest blocks each weighed 18 tons.

I have long wanted to see Mr. Flood's brownstone.  Skipping out on a few sessions at AGU allowed me to reach this goal. The mansion is rather handsome and very out of place on its block surrounded by gargantuan and mostly granite buildings.  And it is clear that no one has polished the bronze fence in decades. 

The main brownstone quarries were in Portland, Connecticut.  First used for building in the 1650s, brownstone started to spread widely in the late 1700s and reached a peak by the last decade of the 19th century.  Following devastating floods, the quarries shut down around 1936, but not before the removal of 10 million cubic yards of rock. 

From a geologic point of view, brownstone has long attracted attention.  The red sands were part of an extensive series of sediments deposited in rift basins formed 200 million years ago by the separation of North America and Africa and the incipient opening of the Atlantic Ocean.  These sediments record more than 35 million years of time and stretch from South Carolina to Newfoundland.  The sediments also preserved the tracks of thousands of dinosaurs that roamed the wet sands near streams and lakes in the basins.  More than 20,000 of these tracks, including the legendary Noah’s Raven, are now displayed at the Amherst Museum of Natural History. 

James Flood’s residence was the lone mansion on Nob Hill to survive the 1906 earthquake.  It was, however, only a shell as fire had burned out the interior.  Flood had died in 1889 and his daughter sold the gutted building to the Pacific Union Club.  They hired the architectural firm run by Daniel Burnham to redesign the mansion.  Ironically, Burnham was the architect of the World’s Columbian Exposition and its White City, which contributed to white stone replacing brownstone as a favored building material.  The Flood residence is listed on the National Register of Historic Places.  Only members and their guests are allowed in the building now.

 

Sunday, December 14, 2008

A Streetcar to Subduction

I wish I could lay claim to coming up with the title for this post, but I cannot. The title, officially Streetcar to Subduction and Other Plate Tectonic Trips by Public Transport in San Francisco, is from a wonderful paper by the late Clyde Wahrhaftig. Originally written for the AGU in 1979, the paper was updated in 1984. Wahrhaftig described six trips that one could take by public transport around San Francisco to see the area's geology. The rare and expensive booklet (six copies were available on amazon.com from between $60 to $130) is a pleasure to read, not only for the geology but also for Wahrhaftig's insights on history and architecture.

The J Church line is the so designated Streetcar to Subduction. With a little effort you can see pillow basalt, sandy turbidites, and radiolarian chert, basically a microcosm of typical oceanic crust. You can learn about how two high school student broke into the supposedly impregnable New Mint Building, just weeks after it opened, and you can learn to identify and avoid poison oak. On another route Wahrhaftig gives an introduction to San Francisco architecture and on one more he reveals how residents saved their houses during the post-1906 earthquake fire by soaking cloth in wine and spreading the material on their roofs. He also shows where to see serpentine throughout the city.

Born in Fresno, California in 1919, Wahrhaftig was an avid outdoor explorer and field geologist. He died in 1994; a thoughtful obituary is available on the UC Berkeley web site. He didn't drive and often eschewed conventional means of travel. As someone devoted to making geology accessible to everyone, he put together his now legendary guides to San Francisco rocks. In addition to Streetcar, he also wrote A Walker's Guide to the Geology of San Francisco, which does contain one walk that focuses specifically on the building stone of the city.

Tuesday, December 9, 2008

Gary Cooper and the Stones of San Francisco

With the upcoming AGU annual fall meeting, I want to look at some of the building stone used in San Francisco.  Despite the area's abundant stone, the earliest fireproof granite building used stone quarried, cut, and fitted together in China.  Known as the Parrott Block, it was built in 1852.  The blocks had been labeled with Chinese characters and shipped to San Francisco, to be assembled by Chinese workers.  The three-story building survived the 1906 earthquake and fire but was razed in 1926 for the Financial Center Building, now remodeled as the Omni Hotel. 

Various rock trickled into San Francisco in the following decades. By the end of the century two of the most prominent were a sandstone quarried near Sites and a granite from Raymond.  Sites is about 100 miles north of the bay area, in the Sacramento Valley, whereas Raymond is 150 southeast in the foothills of the Sierras.  Both rocks reached the city by train. 

Colusa sandstone quarry - From: http://quarriesandbeyond.org/states/ca/quarry_photo/ca-colusa_photos.html

Two quarries in Sites provided stone.  A. D. Knowles opened his quarry in 1886, followed in 1890 by the John McGilvray Stone Company.  Known in the trade as Colusa Sandstone (the town of Colusa is about 25 miles away), the rock comes from the Upper Cretaceous Venado Formation, a several-hundred meter thick layer of submarine fan deposits.  They are part of the Great Valley Group, tens of thousands of feet of muds, silts, and sands that accumulated in a forearc basin found between the Sierra Nevada magmatic arc and the Franciscan subduction complex. 

The Ferry Building was the first great structure made of Colusa rock.  Other well-known buildings are the St. Francis Hotel, Music Temple in Golden Gate, and the Flood Building.  The stone was also shipped to Hawaii.  It is generally bluish gray or buff, though a recently opened quarry about one mile north of the original quarries markets the sandstone as a brownstone.  Like other sandstones during fires, the Sites rock spalled heavily during the post-1906 earthquake infernos. 

Raymond Granite Quarry - 1905 -- From: http://www.sjvls.org/photoheritage

The Raymond granite quarry opened in 1888 on property locally known at the time as Dusy’s Rock Pile.  Light gray in color, the Raymond rock is classic, Sierra Nevada subduction zone granite, and is now sold as Sierra White by the quarry’s present owner Cold Spring Granite.  Raymond granite was used in the San Francisco Civic Center, City Hall, Palace Hotel, and numerous buildings on the UC Berkeley campus.  The new main San Francisco library, built in 1996, also has a granite fa├žade from the Raymond quarry. 

The stone, or at least the quarries, achieved a bit of notoreity in 1949 in the movie adaptation of Ayn Rand’s The Fountainhead.  At a low point in his career, architect Howard Roark, played by Gary Cooper, retreats to a job in a quarry.  The quarry in the book is in Connecticut, but since the film was shot in California the Raymond quarries had to stand in for Connecticut.  Although limited, the scenes in the quarry with Cooper and Patricia Neal are some of the movie’s most famous and controversial because of their sexual imagery.  And for those inclined to stone, the shots do a fine job of depicting quarry technology.

Sunday, December 7, 2008

The HMS Challenger Sets Sail

As Michael Ryan notes on his Paleoblog, today is the anniversary of the day the HMS Challenger set sail in 1872. The expedition spent four years sailing over 69,000 nautical miles charting the depths of the seas.  The crew's discoveries, including the deepest spot on the planet, an immense chain of subaqueous volcanoes, and unexpected diversity, added more evidence to the validity of the theory of evolution and laid the groundwork for one of the other great theories of science, plate tectonics. If you want to know more about the HMS Challenger, I recommend geologist and science writer Richard Corfield's first rate book, The Silent Landscape.  

Corfield mixes journal information from expedition members with details from the scientist’s 20-volume report to tell the tale of the HMS Challenger, what Corfield calls the world’s first sea voyage devoted exclusively to science. As he notes, the journey of the HMS Challenger marked several turning points.  It was the last great voyage of the Victorian era.  It helped lay to rest “the belief that secular questions can be answered by religion.”  It showed that science and the search for knowledge were worthy of government funding and it opened up nearly two-thirds of the planet to exploration that continues to this day.  The expedition deserves to be included on the short list of great British voyages, and Corfield does a fine job of showing why. 

Wednesday, December 3, 2008

The Stones of Florence

I thought I would follow up my previous post on Brunelleschi’s Il Badalone by looking at the stone used in the Duomo, or Santa Maria del Fiore, as it is officially known.  According to Ross King in his highly readible Brunelleschi’s Dome, the planners ordered three colors: verdi di Prato, marmum rubeum, and bianchi marmi—green, red, and white, respectively.  Like many writers, King refers to the stone as marble.  Only the white stone, however, is a true marble.  

As the name implies, the first stone is green.  It is a serpentine, quarried for centuries near the town of Figline, a few miles from Prato, northwest of Florence. The name comes from the stone’s resemblance to a serpent’s skin, or so say some, from the stone’s use as a medicinal remedy against snake poison.  In the building trade, serpentine is commonly called Verde Antique, or Verde Antico if the seller is feeling fancy.  Serpentine forms from the metamorphism of magnesium-rich rock such as peridotite. 

The red stone of the Duomo is a very fine grained limestone quarried in several locales near Florence.  It was deposited in an open, marine environment around 190 million years ago.  Geologists refer to this layer as the Rosso Ammonitico, due to the abundant ammonite fossils.

Bianchi marmi is better known as Carrara marble, the material that Brunelleschi’s Il Badalone was supposed to carry up the Arno River.  The Carrara began life as a fine-grained, calcite mud deposited in the same sea as Rosso Ammonitico but 10 million years later.   It became marble around 27 million years ago when the Corsica-Sardinian microplate rammed into the Italian peninsula.  As the plate’s basalt, gabbro, and sediments piled on the limestone, it metamorphosed it into a marble that is almost 100 percent calcite. 

(View up toward Mount Maggiore, Carrara, Italy)

King is not alone in using the term marble to describe non-marble stone.  To the Romans, who called marble marmor, from the Greek adjective marmareos, meaning shining or shimmering, marble referred to any hard rock suitable for sculpture or architecture.  Such “marbles” might include granite, breccia, porphyry, or serpentine.  Go to any store selling architectural stone and you will find that the Roman tradition continues with a plethora of non-metamorphosed limestone labeled as “marble.”  I have no idea if any are good for snake bites.

Friday, November 28, 2008

The Sea Going Monster

Moving building stone has long taxed humanity.  For instance, last summer’s attempt at ice age revisionist history, the movie 10,000 B.C., showed that mastodons were the primary movers of stone 

at the pyramids.  Okay, maybe the movie makers made a mistake but transporting tons of rock is not easy.  For example, Michelangelo narrowly escaped death twice when great columns of marble he was moving fell and almost crushed him.  Stone movement was so important that it led to what many consider the world’s first patent, granted on June 19, 1421 to Fillippo Brunelleschi.

I learned of Brunelleschi’s patent while reading Robert Clark’s new book Dark Water: Flood and Redemption in the City of Masterpieces, which tells the story of the 1966 flood that devastated Florence.  Clark begins by tracing the history of art and artists in Florence before preceding to details of the flood and its aftermath.  One of the artists he features is Brunelleschi, best known as the architect of the dome of the Duomo in Florence.

Brunelleschi’s patent covered a boat that would be used to “bring in any merchandise and load on the river Arno and any other river or water, for less money than usual.”  Not merely content with ensuring Brunelleschi’s intellectual property rights, the patent noted that if anyone attempted to build their own vessel it would be destroyed by fire.  And you can be sure it would have been; Brunelleschi was notoriously secretive and vindictive.

Known as “Il Badalone,” or the sea-going monster, the vessel wasn’t completed until 1428, when it was scheduled to carry 100 tons of marble from Pisa, 55 miles up the Arno River to Florence.  That marble had been quarried in Carrara, another 30 miles north of Pisa.  Famous as the material that allowed Augustus to boast “I found Rome a city of bricks and left it a city of marble,” Carrara marble achieved even greater fame when Michelangelo used it for his David, Pieta, and Moses.  The brilliant white marble is still widely used for sculptures and as building stone.

(Drawing by Mariano Taccola of Il Badalone)

We do not know exactly how the boat was made because no detailed accounts exist.  The one drawing, by Brunelleschi’s contemporary Mariano Taccola, shows a flat-bottomed vessel getting towed upriver by another boat.  Oxen could also have been used to pull Il Badalone up the Arno.

Unfortunately for Brunelleschi, his monster boat made it only about halfway to Florence before sinking, for unknown reasons. Brunelleschi not only lost all of his marbles but also lost one-third of his wealth in the Badalone fiasco. Its failure, however, did save one life. His rival Giovanni di Prato, who had called Brunelleschi a "pit of ignorance" and a "miserable beast and imbecile," had vowed to commit  suicide if Badalone had succeeded.  Brunelleschi eventually recovered his fortune and other boats eventually brought Carrara marble to Florence for use in the Duomo. 

Monday, November 24, 2008

The Natural History of King Kong

The other night I watched a movie about Megaprimatus kong, better known by his non-scientific sobriquet, King Kong. And I thought he was just a rather large representative of the species Gorilla gorilla. Did you know that Kong was the last surviving member of his species? Did you even know he had a scientific name? He wasn't alone. The nasty, toothy worms that ate some of the film crew were Carnictis and the dinosaur gang of three that battled M. kong were Vastatosaurus rex. At least that's what the gang who made the 2005 version of King Kong tell us in their mockumentary about the natural history of Skull Island. The extra film footage is included in the DVD version of the movie.

While I cannot recommend the main feature, the mockumentary makes a fine addition to the geomovie oeuvre discussed earlier this year at Magma Cum Laude and Geotripper. Skull Island: A Natural History includes "historic footage" of expeditions to the island, talking heads, and material from King Kong. We learn that the island is a "perversion of evolution," where dinosaurs survived because underground vents kept the island temperate during the prolonged cooling following the asteroid that hit 65  million years ago. Unfortunately, or perhaps fortunately, the geologic instability that led to the survival of the dinosaurs ultimate doomed Skull Island, as a 9.2 magnitude earthquake led to the island's disappearance into the sea, coincidentally just after the original King Kong movie crew finished shooting in the 1930s.

I have to hand it to the movie makers because much of what they discuss is based on plausible science, even if applied to a made up world.  This does not necessarily mean that the movie is believable and it's too bad that none of this science comes across in King Kong but at least the mockumentarians did take the time to research the facts. Another plus for the mockumentary is its length, an easy-to-watch 17 minutes versus the butt numbing three hours of the film. 

Wednesday, November 19, 2008

Of Bees and Building Stone

Our modern pollinator crisis may have unseen consequences. For example, few people will now be born surrounded by bees. This may not seem to be a bad thing but consider the birth of Ethiopian king Lalibela in the 12th century. Legend holds that at his birth bees swarmed the child, which many regarded as a propitious omen. His older brother Habray, like a few notorious older brothers, was not pleased, and figured that the best way to deal with his chosen brother was to kill him.  Unfortunately for Habray, Lalibela didn't die but ascended to Heaven, where God told Lalibela that his destiny was to build 11 great churches as a "New Jerusalem."

I learned of Lalibela and his churches at the Lucy's Legacy exhibit at the Pacific Science Center in Seattle. In addition to showcasing perhaps the second most famous female in early human history, the show provides a fascinating account of Ethiopia and its importance to Judaism, Islam, and Christianity. Lalibela was part of the Zagwe dynasty, which promoted a reemergence of Christianity.

King Lalibela carved the churches in a red tuff, which interbeds with thick basalts produced by the east Africa rift system.  This rift setting is similar to other areas of plate breakup, which produced stone such as the diabase of Gettysburg and the brownstones of New York. In each of these rift valleys, volcanics also erupted, though no one on North America had the inspiration to carve churches in the rock.

According to the Lucy exhibit, to accomplish the task of hewing the buildings, human masons worked during the day with angels taking over the night shift. Archaeologists, however, say it took at least 150  years and not 24 years, as tradition claims. Starting at the top on arches, vaults, and ceilings and continuing without scaffolding down to the floor and doors, masons worked with picks and levers to remove the soft, porous rock.

The eleven buildings are found in the town of Lalibela, about 600 kilometers north of the Ethiopian capital of Addis Ababa. They form two groups divided by the River Jordan, though the most remarkable structure, Bete Giyorgis (the House of St. George), sits a few hundred yards away from the northern group. Shaped like a Greek cross, it is freestanding in the center of a square shaft measuring 22 by 23 meters. South of the river, Bete Amannuel is also a single monolith, 18 meters tall and 12 meters wide on each side. Inside many of the churches were elaborate paintings of geometrical patterns, animals, and Bibilical scenes.

Despite having been listed as a UNESCO World Heritage Site in 1978, the buildings and paintings have suffered in the harsh climate and unfavorable geologic conditions (easily weathered clay minerals and weak layers in the tuff). To slow the deterioration, temporary shelters have been built, though they are neither handsome nor completely protective. Perhaps we need another swarm of bees to inspire new shelters. 

Friday, November 14, 2008

The Stones of Duke City

My wife is in Albuquerque for a few days. We drove through Duke City this summer and I can recommend two things to do in town. One, go to the legendary Frontier Restaurant, and two pick up a copy of George Austin's guide to the geology of the downtown area.  Written with both geologists and non-geologists in mind, the booklet contains a two-hour long, self-guided tour of Albuquerque's building stone. It also includes sections on local geology, quarrying, and milling. 

Austin, who has worked for the New Mexico Bureau of Geology and Mineral Resources for over three decades, ably weaves history, architecture, and geology into a fun expedition.  We discover clam, snail, and crinoid fossils, Albuquerque's first skyscraper (built in 1922), and billion-year-old granite called Fred Red. We also learn about Route 66 and Pueblo Deco architecture.  As in most cities, the building stone spans the globe and geologic time, from as young as a few hundred thousand years to as old as 2.6 billion years. 

The book is available on line or in Albuquerque for $8.50. The title is Scenic Trips to the Geologic Past #17, Albuquerque Downtown from a Geologic Point of View--A Walking Tour of the City Center. 

And if you are interested in reading more about Albuquerque, two fine books are Rudolfo Anaya's Alburquerque, a novel of politics, family, and boxing, and Edward Abbey's brilliant Brave Cowboy, which was made into a movie starring Kirk Douglas. Douglas, by the way, called it his favorite film. 

Tuesday, November 11, 2008

Geology of War

"The whole battle is about trying to take an igneous intrusion away from another army," says Robert Whisonant, a geologist at Radford University in Virginia.  Whisonant is quoted in Erin Wayman's fascinating article about geology and the Civil War, which appears in the November issue of Earth magazine (formerly Geotimes.)

Wayman focuses on two of the most important battles in the war: Antietam and Gettysburg. Whisonant and his fellow researcher, Judy Ehlen, observe that one of the deadliest battlefields at Antietam was the Cornfield, where three times more solders died than at the adjacent Burnside Bridge.  They attribute the totals in part to the Cornfield's underlying limestone, which has weathered flat, whereas the more resistant dolomite and shale of Burnside had eroded into a safer terrain of hills and ridges, allowing soldiers to hide and maneuver unseen.

Whisonant's quote refers to Gettysburg where a diabase (dark igneous rock) had intruded into softer sediments and formed a boulder-rich, hilly terrain.  The Union army held the 25-meter-high Cemetery Ridge and the Confederates were on the lower Seminary Ridge. Between the two was a plain, formed by the erosion of the soft sediments.  More than 12,000 Confederate soldiers died when they tried to cross the unprotected plain during the infamous Pickett's Charge. With that loss the South retreated.

For me, the other interesting story of Gettysburg is the stone itself.  The battle-influencing diabase formed around 200 million years ago, as North America and Africa separated during the breakup of Pangaea. The split produced a series of rift valleys that stretch up the Atlantic Coast, including one now found in Connecticut and Massachusetts where dinosaurs left behind thousands of tracks. Collected in the middle 1800s by Edward Hitchcock, the tracks can be seen at the Amherst College Museum of Natural History.  The area is also famous for producing a brown sandstone used in the building trade throughout the east.  The rock is better known as the material covering hundreds of brownstone rowhouses. 

If you are interested in more information, the Pennsylvania Geological Survey has two publications on line. The first is a reprint of a 1962 report on Gettysburg and the second is 2008 field guide to the battlefield. The National Humanities Council also has a great reference spot with more articles by Whisonant. 

General Robert E. Lee may have been a brilliant tactician but he appears to not have been a good geologist. But in his defense, geology was still a young science and most of what we know now could not have even been imagined in the 1860s.