Boston: Where it All Started

I moved to Boston about a dozen years ago. My wife and I had been living in Moab so it was quite a shock to arrive in the Hub. Gone were the wonderful red rock canyons, wide open spaces, and 12,000 foot high mountain peaks. Instead, I found concrete canyons, urban density of almost 20,000 people per square mile (compared with less than 2 around Moab), and minimal topography. I was not happy until I discovered the mosaic of geology used to construct the city's buildings: sandstone, granite, travertine, marble, puddingstone, and gneiss.

As I have now discovered, Boston, like most big cities, is built with a range of rocks equal to any assembled by plate tectonics. With a short walk you can find rocks ranging in age from 3.5 billion years old to less than 200,000 years old. There are rocks from every continent except Antarctica. Plus, builders often go to the effort of polishing the rocks, so it is even easier to see the wonderful structures, fossils, and minerals. There were many times I wish I had my rock hammer and a bottle of acid.

I bring this up because today in the Boston Globe there is an article of mine about the great rocks of Boston. Based on a timeline, the story highlights 13 buildings and their geologic and cultural stories. The editor and designer did a great job. I have only one regret, at this point it's not on-line, or if it is I cannot find it, so if anyone out there sees it could you let me know how it looks.

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.

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.

Building Stones of Great Edifices: Great Pyramid

Foraminifera, or forams, are one of the more well known group of fossils.  Most, such as the ones in the Salem Limestone, are wee little critters but one genus, Nummulites, is notorious for the great size of the species.  Nummulites are also famous because they are the dominant component in the limestone used at the Great Pyramids.  That stone formed 40 million years ago and is part of series of limey rocks found in Egypt.

 A handful of Nummulites (from Lorraine Cassaza's web page)

These Nummulites have long fascinated visitors to the pyramids.  According to many writers, the historian Herodotus (5^th century BCE) was one of the first to comment on them. He supposedly gave the fossils their name, based on their coin-like shape.  Nummulus is Latin for coin.  But if you read through Herodotus’ Histories he makes no use of the term Nummulus and only refers generically to shells.  (One Herodotus expert I contacted wrote: “Herodotus would not have used the term 'nummulites' because it is not a term which existed in his time.”) 

A handful of Nummulites (from Lorraine Cassaza's web page)

Several hundred years after Herodotus wrote his Histories, another historian, Strabo, provided additional thoughts on the shells.  In Book 17 of his Geographica, he wrote of chips “that are like lentils in both form and size…They say that what was left of the food of the workmen has petrified; and this is not improbable.”  In Europe, where Nummulites also appear, the ideas for the fossils’ origins were equally dubious.  Botanist Carolus Clusius (1526-1609) referred to an old legend from Transylvania.  The fossils were “pieces of money turned into stone by King Ladislaus, in order to prevent his soldiers from stopping to collect them just when they were putting the Tartars to flight!"  

Such fanciful theories soon gave way to a more scientific understanding but in 1912 a new idea about Nummulites arose.  In that year, invertebrate paleontologist Randolph Kirkpatrick self-published his The Nummulosphere: an account of the Organic Origin of so-called Igneous Rocks and Abyssal Red Clays.  It proposed that Nummulites were responsible for the formation of all rocks, whether igneous, extraterrestrial, or sedimentary. In a follow up to the book, he wrote “The book was, I believe, regarded by some as a symptom of mental derangement on the part of the author.”  He didn’t disagree and added that the earlier book lacked evidence, which he would now possessed.

 (From Wikipedia)

According to researcher Lorraine Casazza, Nummulites are some of the largest single-celled organisms ever.  They were able to reach their great size by growing complex shells, which leads to a large surface area relative to volume.  She writes that the most accepted reason for gigantism is that algae live inside the foram and are able to photosynthesize, which facilitates rapid shell secretion.  Her research focuses on whether this hypothesis is correct.  Judging from the long term interest in Nummulites perhaps they are the most curious aspect of the pyramids.  

Presidential Stone: Whitest and Prettiest

Although Abraham Lincoln’s birthday was last week, we honor him today, as will I, by looking at the building stone of the Lincoln Memorial.  In January 1913, a federal commission approved architect Henry Bacon’s plan for the monument. In contrast with the  common practice of using a steel infrastructure, Bacon proposed white marble walls, columns, and floors. His preferred stone was the Yule marble from Colorado.  

Lincoln Memorial (From Wikipedia)

First described geologically in 1874, the Yule quarry had only opened in 1904 and few easterners had seen it.  Bacon had visited it in 1912 on a trip west and was impressed both by its beauty and by the large blocks the quarry produced.  One long-time supporter called the Yule the “whitest, prettiest, and all things considered, the best marble.” 

The Yule marble was originally deposited as a fine-grained, limey mud in an open shallow sea 345 million years ago when water covered western Canada and most of the United States.  Geologists call this rock the Leadville Limestone in Colorado.  An intrusion of magma 32 million years ago generated the heat necessary to locally metamorphose the Leadville into marble.

The quarry is located about 30 miles west of Aspen, Colorado, at 9,300 feet above sea level.  It is completely underground.  Workers took the stone out of the side of a mountain through portals and lowered them down to a train,which carried the blocks another 3.5 miles to a mill.  Final cutting and shaping required the largest mill in the world, as each of the 38 columns consisted of  25-ton blocks.

Yule quarry (From Wikipedia)

The contractor completed the shell (a nifty Flash program showing construction) of the monument in October 1917.  World War I prevented a dedication from occurring until Memorial Day, 1922.  Coincidentally, this was the same year that the Yule quarry started back in business after shutting down in 1917; in 1919, it had sold to a junk dealer at a sheriff’s sale.  Still popular, the quarry provided a 56-ton block for the Tomb of the Unknown Soldier in 1931, but then closed again in 1941. One year earlier a major crack had appeared in the massive block. 

Tomb of Unknowns (From Wikipedia)

The quarries remained closed until 1990 and limped along closing again in 1998. Yule marble, however, seems to not fade away easily.  New owners reopened the quarry in 1999. They have continued to struggle but have a new project; they are now looking to replace the Tomb of the Unknown Soldier with a new block of marble. 

Best Building Stone Site on the Web

By far the most interesting site on the web for building stone is Peggy and Pat Perazzo’s Stone Quarries and Beyond.  Clearly a labor of love, the site is packed full of photographs, scans of articles, details about quarrying, and state by state lists of buildings and their stone—basically everything one could want on building stone history. 

From Stone Quarries and Beyond

Of the two, Peggy is the collector and organizer and Pat is the web master.  Peggy’s interest in stone started in a graveyard.  In the late 1990s, as part of a class she was taking on local history at Los Medanos community college, in Pittsburg, California, Peggy decided to survey and photograph stones in local cemeteries.  She wondered where the stones came from and discovered that such information was not easy to find.  When she did locate a point of origin she found that much of the marble, limestone, and granite wasn’t quarried nearby.

Some stone arrived from other areas of California but tons came from Vermont and Italy.  Finished cemetery stones (minus such important info as name or dates) are called blanks and could be ordered through places such as Vermont Marble Co., but also Sears and Roebuck and Montgomery Wards.  Finding who sent the rock, however, didn’t always help.  For example, Vermont Marble had quarries as far away as Alaska. 

From Stone Quarries and Beyond

From cemetery stones, she expanded out to bridges, buildings, and other structures and then attempted to match the stone with its origin quarry.  As her piles of data grew, she decided to establish a web site.  “I already was maintaining a genealogy/history web site for the Yolo County CAGen Web Project for which Pat was the web master,” says Peggy.  He agreed again to help.  “It’s a joke between us now that he thought he could get it done in two or three weeks!”  The web site went on line in 2001 and the Perazzos add content practically daily. They report that they had over 2,000,000 hits in 2008.

Peggy’s favorite part of putting together the web site is researching the state by state listings.  “It's like I'm touring the state in person and meeting the people,” she says.  Each state has its own personality.  “Researching coastal states is very interesting because of the sea transportation and quarrying along the coast; but when you go inland, you find other kinds of quarrying and people.”  

Her state sections are the site’s most useful and interesting.  Each one lists geology resources, research resources, quarries, quarry links, and background history.  In addition, Peggy has put together a list of structures and monuments that use that state’s stone.  It is an astounding amount of information, particularly the accumulation, copying, and posting of historical articles and pictures.

“My biggest surprise is learning how really important and publicly valued the quarry industry was to our country in the 1800s and early in the 1900s, although our quarry industry is very "young" compared to the industry in other countries, Peggy says.  “Many times people see these "holes" in the ground as eyesores; but if you read the old magazine articles, the stone industry was well respected, well-known as producers and employers, and valued in the past.”  Fortunately for many, Peggy and Pat are helping to make sure those stories will stay alive. 

What's In A Name

As someone interested in names and what they mean, I am regularly intrigued by the terms used in the building stone trade.  Often the names give an insight to place of origin.  For example, we have the world famous Carrara marble, nationally known Georgia Cherokee Marble, or locally recognized Tenino Sandstone (from Tenino, Washington).  Stone names can also convey color, such as Coral Red Granite, Black Ice Marble, and Blue Pearl, or texture, Roxbury Puddingtone, Birdseye Marble, and Tapestry Granite.

Names, however, can also mislead.  Minnesota’s Rainbow granite is a 3.5-billion-year old gneiss, which happens to be the oldest commonly used building stone in the world. (Ironically, one correctly labeled class of granites, called rapakivi, gives too much information as rapakivi is the Finnish word for crumbly.)  The other commonly mislabeled rock is limestone, often called marble, even ones such as the fossil-rich Treuchtlingen marble from Germany. 

 3.5 bya Morton gneiss aka Rainbow granite

The more fascinating stones come with a story.  The island of Chios has produced portasanta, a stone often compared to roast beef in color and texture; its name translates to holy door, a reference to its use as door jambs at St. Peter’s.  From France comes another reddish rock, Cervelatte Marble, a named derived from is similarity to sausage made in Switzerland and Germany.  Cervelatte comes from the Latin cerebrum, in reference to the brains formerly used in the sausage.

 Portasanta

One of the world’s most famous marbles is that used in the Parthenon in Athens. Roman stone cutters knew of the white marble as Marmo Greco Fetido (fetid Greek marble) and Marmo cipolla (onion marble), because “when sawn it emits a fetid odour,” wrote Mary Winearls Porter in What Rome Was Built With: A Description of the Stones Employed in Ancient Times for its Building and Decoration.  This is not an unusual phenomenon; organic remains in the rock can disintegrate and form a sulfurous gas, which gets trapped in the crystal lattice.  Breaking the stone releases the gas.  Cutting to the chase, the British labeled their odoriferous rock Stink Stone.

The Brits also have many ancient words sprinkled into their stone names. Kentish Rag utilizes a word first used in 1272 to refer to any “sedimentary rock readily broken into thick slabs as paving” or so says the OED.  The commonly used freestone also appeared at this time, compared with sandstone, which was not used until 1668. And then there’s clunch, which sounds like a stomach ailment, but actually refers to hard layers of the chalk marl in Cambridgeshire.

My favorite name, however, comes from Brazil.  I don’t know what it means but simply like the sound of Uba Tuba.  What’s your favorite stone name?

Our Nation's Building Stones

So you’re heading out to Washington D.C. to attend the inauguration and wondering what to do in the down time between the Bruce Springsteen concert, primping for the Inaugural Ball, and chatting up your local congressional representative on the importance of  a good geology education.  Well, like that self-professed geogeek, Mr. Obama, (okay I think he just called himself a geek but I am guessing that he secretly likes rocks), one thing to do is to explore our nation’s capital and check out the building stone.  

In a city of stately buildings, stone has long been the premium material.  One of the first was quarried about 40 miles south of Washington along Aquia Creek in Stafford County, Virginia.  Popular between 1790 and 1840, the Lower Cretaceous sandstone is rich in quartz sand and pebbles.  It was also known as ‘Virginia freestone,’ and was used for the White House, Treasury Building, the Old Patent Office, and the older parts of the Capitol.  Unfortunately, the Aquia Creek rock suffered from many flaws and weathered poorly, so that it soon had to be replaced or painted over.  

Gateposts (From USGS Pub. Building Stones of Our Nation's Capital) 

You can still find it indoors at the Old Patent Office and in rooms next to the Capitol rotunda.  Outdoor examples include the Old Patent Office, the boundary stones of D.C., and three gateposts and one gatehouse, formerly at the Capitol.  They can now be found at 15^th St. NW and Constitution Ave. NW. 

The most popular building material, and one that has weathered far better, is the Salem Limestone.  As I have noted before, it is a 330-million-year old rock quarried in and around Bloomington, Indiana.  You cannot travel very far in Washington without running into a building made either all or partly of Salem.  These include the Botanic Gardens, the GSA Building, US Holocaust Museum, Interior, Jefferson Memorial (calcite from the Salem and marble have weathered and made stalactites and stalagmites in the basement), Lincoln Memorial, National Theater, and scores of more.  

Department of Interior (From USGS Pub. Building Stones of Our Nation's Capital) 

You can also find a brownstone, from quarries located along the Potomac River, near Seneca, Maryland, 20 miles northwest of Washington.  Like the brownstones of Connecticut, the Seneca sandstone formed in massive rift basins that opened 200 million years ago during the breakup of Pangaea.  The Smithsonian Castle completed in 1855, uses this brownstone, which has weathered to dark red from its original lilac gray.  I recently learned from Through the Sandglass of a great Mark Twain quote about said stone.  In a letter published in the March 7, 1868 Territorial Enterprise, he wrote of the “poor, decrepit, bald-headed, played-out, antediluvian Old Red Sandstone formation which they call the Smithsonian Institute.” 

Smithsonian Castle (From USGS Pub. Building Stones of Our Nation's Capital) 

I will end my short tour with the Washington Monument, the tallest masonry structure in the world.  The lower 152 feet use Texas marble, quarried in Maryland.  Construction on this section ran from 1845 to 1854.  Not until 11 years after the Civil War did building again begin again, now with marble from Lee, Massachusetts.  Only four layers were laid; this marble was too expensive.  Builders returned again to Maryland quarries but this time they got stone from Cockeysville, north of Baltimore. 

If you want to see more or learn more about stone of Washington, D.C., you can consult two excellent publications.  The USGS has put their Building Stones of Our Nation’s Capital on line. 

The second is the Building Stones and Geomorphology of Washington, D.C., written by Jim O’Connor, the late geologist for the District of Columia.  Enthusiastic about making geology accessible to everyone, he wrote and taught extensively about the local geology of the capitol. 

Building Stone Books

I am not alone in my passion for building stone. Today, I wanted to explore a few of the other books about building stone. This is not close to a complete list but some that I have referred to over the years. And it does not include any material on Washington, D.C., which I will write about later this week for those of you headed to the inauguration on January 20.

The list is in no particular order. Any suggestions would be appreciated.

A Geologic Walking Tour of Building Stones of Downtown Baltimore – Available both on line and as downloadable PDF file.

Stone Landmarks: Flagstaff’s Geology and Historic Building Stones by Marie D. Jackson – A beautifully designed, well-written tour of Flagstaff.  Includes a walking tour and wider explorations of the area. You can download an order form at the link.

In Limestone Country by Scott Russell Sanders – A literary exploration of the men and geology of the building stone region around Bloomington, Indiana.  Sanders’ writing is clear, passionate, and compelling.

Albuquerque downtown from a geologic point of view – I mentioned this book in November but felt it needed to be in this list.

Guide to Stones Used for Houses of Worship in Northeastern Ohio Cleveland Ohio, by Joseph Hannibal, Curator of Invertebrate Paleontology at the Cleveland Museum of Natural History. Published by the Sacred Landmarks Partnership of Northeast Ohio.  Dr. Hannibal has done extensive research on the building stones around Cleveland and provides geologic and cultural information on the many churches of the northeastern Ohio.

Building stones of Pennsylvania’s capital area  by Alan Geyer – This doesn’t seem to be in print any more but is availabe through libraries.  It is publication EG5 in the Pennysylvania Geological Survey’s Environmental Geology series.

Geology along Chicago’s Michigan Avenue – A nice walking tour in Chicago with good photos and information. Particularly note the section of the Chicago Tribune Tower with its wonderful carvings of Salem Limestone.

A gallery of architectural geology – Oriented toward Chicago but also with photos of a few buildings outside of the Windy City.

Dimension Stone in Victoria, B.C. – Described as a city guide and walking tour of this wonderful little city in Canada. Available as a 12mb PDF.

Building Stone and Historic Structures in Downtown, Toronto – Written by C.R. Fouts, E.B. Freeman, K.M. Kemp, C. Marmont, and D.G. Minnes – A field trip guide prepared for a 1991 meeting in Toronto.

The Stones of Rome – Next time you venture to Rome, check out this page, full of much information. 

Breaking Away: The Building Stone Movie

Prompted by Silver Fox and inspired by Geology News, this post focuses on one of my favorite geology movies, Breaking Away.  The film takes place in Bloomington in the late 1970s and centers on four recent high school graduates: Dave, Moocher, Cyril, and Mike.  Ostensibly about the relationship between stone mill workers, or Cutters, and college kids, Breaking Away is filled with the angst and self-doubt sewn into young men who cannot follow their father’s footsteps.  “They’re gonna keep calling us “Cutters.”  To them it’s just a dirty word.  To me it’s just something else I never got a chance to be,” says Mike, the character played by a young Dennis Quaid in Breaking Away. 

With no work in the building stone industry, the guys have nothing better to do than loaf around, complain about the advantages of college kids, and swim in the abandoned quarries.  Those quarries are all in the Salem Limestone, a 330-million-year old rock unit that is the most commonly used building stone in the country.  The Salem formed in a quiet sea, which covered what we now call the Midwest and is most analogous to the Bahamas where limestone is now forming. It is a fossiliferous layer rich in crinoid stems, bryozoans, brachiopods, and forams.

Joe Palooka in Oolitic, Indiana

Out of the great beds of white rock came the stone climbed by King Kong (Empire State Building), bombed by terrorists (The Pentagon), and walked through by hundreds of thousands of immigrants (Ellis Island).  In the late 19^th and early 20^th centuries, it was the stone to use for grand buildings everywhere, as well as for tomb stones, statues, and many other more modest architectural features.  If you are interested in reading more about the Salem, I recommend Scott Sanders' excellent In Limestone Country. 

Unfortunately, you cannot get to the quarry where the guys swam in the movie.  It is blocked by a fence and “No Trespassing” signs.  You can, however, see the hole that the Empire State Building came from.  It is near a small cemetery just north of Oolitic, Indiana.  You can also drive through the Salem-rich Indiana University campus in Bloomington, where much of Breaking Away was filmed.

The hole where the Empire State Building was quarried.

Breaking Away is a near perfect movie, at least if you want a good view of a small part of the building stone world.  One extended scene is shot in a limestone mill and features massive cutting tools called gang saws.  When the guys go swimming, you can get a feel for the size of the quarries.  The dialogue between Dave and his father is hysterical.  And Dave, the star, rides a bike, which leads to the final, uplifting moments of the movie, a bike race between our four heroes and the snotty, snooty college boys.  What more could a geology-loving, bike-riding geek want? 

The Politics of Building Stone: Seattle

Twenty years ago today a building stone brouhaha erupted in Seattle.  On that snowy Friday, local newspapers reported that Metro, which managed King County’s sewage treatment and public transportation, would have to pay for, but not use, a half million dollars worth of granite that it had purchased for a new bus tunnel through downtown Seattle.  The reason for the rejection was that King County (Seattle is the county seat) had a policy that it could not use or purchase any goods “manufactured or fabricated” in South Africa because of apartheid.

The conflagration began when Eddie Rye of the Black Contractors Coalition notified Metro about its planned use of a green granite quarried in South Africa.  At the time, the stone, known in the trade as Verde Fontaine, sat in Italy, where it had been shipped for cutting and polishing.  Metro Council executive Alan Gibbs responded that using the stone would be “an affront to the community.”  Officials added that Rye’s notification was the first time Metro had heard of the granite’s origin and that none of the South African had been shipped to Seattle.  Turns out that neither statement was true and that a second South African granite had also been purchased. 

 Travertine and Verde Fontaine

Quarried near Bitterfontein, about 200 miles north of Cape Town, the pine green Verde Fontaine solidified underground over one billion years ago.  The green coloration comes from the mineral chlorite, which forms from the alteration of iron- and magnesium-rich minerals within the rock.  The granite is part of a suite known as Spektakel and were emplaced into supracrustal rock units (metasedimentary and metavolcanic rocks) that most likely exceed two billion years in age. 

After Rye blew the whistle, officials within Metro described how some had known about the origin of the stone but that they thought that so little was to be used that it wouldn’t be a problem.  They also noted that use of the rock technically wasn’t illegal because it was only quarried in South Africa but cut and finished in Italy. King County Council Chairman Ron Sims, a member of the Metro Council, responded ''It was a morally repugnant decision. Somebody should have to account for that. This was no longer a half-million-dollar 'error.' It was a conscious decision to defy public sentiment.'' 

Accusations continued over the next month ultimately leading to the resignation of Alan Gibbs in late February. ''The buck stops with me,'' Gibbs said at a news conference where he read a formal letter of resignation. ''The events of the last few weeks surrounding the issue of South African granite have been an embarrassment to the agency … This episode needs to be put to rest so the agency can move ahead with the important work before us.''  Two weeks after Gibbs’ resignation, an internal review of Metro concluded that Gibbs had not misled the public.  On September 15, 1990, the bus tunnels under Seattle opened, with walls covered in less polemical rock.

Building Stones of Great Edifices: Stonehenge

This will be the first of what I hope to be periodic postings about the building stones of famous edifices, such as the Great Pyramids, Machu Pichu, and the Great Wall of China.  Suggestions would be welcome. 

Some of the world’s oldest building stones made it into a fine story in this month’s issue of Earth.  Written by English geologist Brian S. Johns and Lionel E. Jackson, Jr., a Quaternary geologist from British Columbia, the article offers a thought provoking and believable account of the travels of the enigmatic rocks used at Stonehenge.  In doing so, they answer one of the great questions posed by anyone who has visited the Salisbury Plain, “How the hell did they do it?” 

From wikipedia

As Johns and Jackson note, this question has led to some dubious answers.  The Celts, Vikings, Phoenicians, Druids, and Romans have all had their day in the spotlight, though the building of Stonehenge, around 4,500 years ago, predates each of these peoples.  Nor were space aliens involved, though that would be a very handy way to explain the many mysteries.  Johns and Jackson don’t provide an answer to who but instead focus on the origin of the stones.  

Two primary types of building stone make up the majority of the monoliths.  The outer ring consists of a 60-million-year old rock known as sarsen sandstone.  (Sarsen is a regional term applied to the boulders found scattered across south central England.)  About 50 sarsen stones occur, either as vertical slabs or horizontal lintels, and comprise Stonehenge’s most famous features, the Pi-shaped trilithons.  The largest sarsens weigh an estimated 40 tons, or about equal in weight to 48 Smartcars.  

The smaller and less abundant bluestones raise more questions.  Made primarily of diabase, but also rhyolite and additional volcanic material, the stones’s origin has been traced to the Preseli Hills of western Wales, more than 125 miles to the west.  At least eight different rock types associated with Stonehenge have been found across seven miles of hills in this region of Wales.  Early researcher Herbert Thomas, who promoted the “human transport” theory for the origin of the bluestones, hypothesized that Stonehenge’s builders sought out these stones because of their magical and medicinal properties. 

Source area for bluestones: From Brian Johns' web site

Johns and Jackson favor a glacial transport model for the bluestones.  They describe how converging ice sheets from Ireland and Wales funneled erratics from Wales in a “trail leading straight to Stonehenge.”  As evidence of such a conveyor belt-like feat, they report on glaciers in Canada, which ferried erratics in a narrow band over 350 miles south.  In England, this phenomenon provided Neolithic Britons with a ready source of stone for their great structure, no matter why they built it.  And that is the great mystery that not even geology can solve.