Mastodon State Historical Site is in Eastern Jefferson County, Missouri, near Imperial and Kimmswick.
I paid a visit on Saturday the 26th of May.

A beautiful little natural history museum is at the top of the hill; this is where visitors can begin their exploration.
Behind the museum, sheer limestone cliffs drop into a lush forested creek valley, with several sets of wooden stairs allowing access to the valley floor.
At the foot of the bluff one finds the areas where some of the world's best mastodon remains were unearthed.
These digs began in the 19th Century and continued with more recent scientific efforts.
In the late 1970's Clovis type weapon points were found imbedded in mastodon bones, proving conclusively that human beings did coexist with the great tusked mammals in this region, thousands of years ago.
There are good hiking trails in the valley, followed by the long climb back up to the visitor's center.

Camera used was a Sears/Ricoh KS-1, loaded with store-branded ASA 200 print film and fitted with a Pentax SMC-M f:1.7 / 50mm lens.
ALL SHOTS WERE HAND HELD AND WITH AVAILABLE LIGHT ONLY (no flash used).
All images are ©2007 E.J.Kowalski.