Category: StreetSmartNaturalist

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.

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.