Earth Science Week 2017 - Wednesday (National Fossil Day™)

Happy Earth Science Week 2017!

Wednesday of Earth Science Week is celebrated as National Fossil Day™.  This summer, during our Out West vacation, we visited two large fossil sites the Mammoth Site of Hot Springs, SD and the Vore Buffalo Jump near Sundance, WY.

The Mammoth Site formed approximately 26,00 years ago when a sinkhole formed.  As the sinkhole filled with groundwater, it began to attract local wildlife (including mammoths).  Unfortunately for the mammoths, the sides of the sinkhole were steep and many mammoths fell into the shallow water where they were unable to escape.  Over time the sinkhole filled with sediment (and the remains of dead mammoths).  Overtime, the sediments surrounding the sinkhole eroded away and the former sinkhole was left behind as a hill!  This amazing site was discovered by accident in 1974 during excavation of a proposed housing development.  The importance of the discovery was recognized immediately.  Today the mammoth site remains an active paleontological dig with 61 separate mammoths being identified to date (along with other Ice Age fauna).

People in this photo give an idea of the scale of the site.

 

The arrows point out mammoth tracks in the sediment.

The goal at the Mammoth Site is to leave as many of the bones in place as possible.  On occasion some bones must be moved due to instability or the possibility of other more complete skeletons lying underneath them.  The site has a large overhead lift system to facilitate removal of bones when needed.

A mammoth skull wrapped in plaster for removal.

The fossils found at the Vore Buffalo Jump are much more recent than those of the Mammoth Site.  This site is also a sinkhole, but rather than accidental the deaths of the animals found here were intentional.  Over the course of 300 years (from about 1500AD - 1800AD) Native American tribes used the site to kill migrating bison by driving them over the edge of the sinkhole.  At least five different tribes used the location over time, as evidenced by stone projectile points found at the site.  While other buffalo jump sites have been located at cliffs, this is the only known use of a sinkhole for the purpose.  Less than 10% of the site has been excavated.

A building has been constructed over the active dig site at the bottom of the sinkhole.

The bones in the sinkhole are so jumbled that it is impossible to tell exactly how many buffalo died here.

 

What's with the ™ after National Fossil Day?  The National Park Service holds a trademark on the phrase National Fossil Day - while they allow use of the phrase, they do require that the trademark appear after the first use of the phrase in a document.