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 (5th 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.