Visitors Guide to
Mastodon State Historic Site

1050 Charles J. Becker Drive
Imperial, Missouri

Accessible Parking Accessible Picnic Facilities Accessible Interpretive Exhibits Accessible Missouri Historical Site Accessible Hiking Trails Accessible Wildlife Viewing Accessible Restrooms

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At the end of the most recent North American glacial era, about 12,000 years ago, the Midwest was populated with megamammals such as giant ground sloths, peccaries, and mastodons. The fossils of a number of these creatures have been found in the Kimmswick Bone Bed near Imperial, Missouri. Paleontologists theorize that the area once contained mineral springs and swamps and that many animals became trapped in the mud. One of the most common bones found in the bone bed are those of the American mastodon (photo left)  that lived from at least 3.75 million to 11,000 years ago. Mastodons are related to modern elephants and as adults they stood between 8 to 10 feet high at the shoulder and weighed between 8,000 to 12,000 pounds. The first recorded report of bones of mastodons and other now-extinct animals in this area was in the early 1800s. St. Louis Museum owner, Albert C. Koch, Ph.D., investigated a report of bones weathering out of the banks along Rock Creek and conducted excavations in 1839. At the turn of the 20th century, nationwide interest in the site was revived when amateur St. Louis paleontologist C. W. Beehler excavated several skulls, jaws, teeth, tusks and other fossils. Railroad tours from St. Louis brought many lay and professional visitors, particularly during the 1904 World's Fair, to visit Beehler's wood shack museum near the bone bed.

Public interest in the site was revived in the 1970s during the construction of I-55. A movement to save the site from future destruction was organized by the Mastodon Park Committee. Through the efforts of the committee, local legislators, private individuals, corporations, and local school children, and with the help of a federal grant, the Missouri Department of Natural Resources was able to purchase the 418 acres of land that included the bone bed in 1976.

Early Native Americans also had reached present-day Missouri by at least 12,000 years ago. For a brief period at the end of the Pleistocene epoch, the lives of humans and mastodons intertwined. In 1979, during a Missouri DNR sponsored excavation, paleontologist Russell W. Graham of the Illinois State Museum provided the first solid evidence of the coexistence of humans and mastodons, as a stone "Clovis" type projectile point was found in association with mastodon bones. This was the first site in eastern North America where this association was conclusively demonstrated.

A museum on the site tells the natural and cultural story of the oldest Native American site that one can visit in the Missouri State Parks system. A full-size replica of a mastodon skeleton highlights the exhibits and is part of a lifescene (photo left) that depicts a Clovis campsite as it may have appeared 11,000 years ago. Other features include numerous exhibits about prehistoric animals, Clovis era Native Americans, and the sciences of paleontology and archeology. An informative slide show runs every half hour (later starting times for Sundays.) Visitors may take the Wildflower Trail that begins next to the museum and leads to the site where the bones and artifacts were found. Although excavations have been closed to protect the bone bed, an interpretive kiosk explains past excavations. A nominal admission fee is charged to adults visiting the museum.

Other Features

The Mastodon Park Committee established the Callison Memorial Bird Sanctuary in 1995. The flowers planted in the small area next to the museum provide food and habitat for butterflies and birds. Nearby benches provide a quiet spot to view birds attracted to the feeders year-round. The park features 3 hiking trails, shady picnic sites with grills, a playground, and horseshoe pits.

The Missouri Audubon Society maintains a checklist for birds that can be seen at this site.

Visiting the Mastodon State Historic Site
The grounds are open daily from 8 am to one-half hour after sunset year-round.
     From December through February, the museum is open Monday, Thursday through Saturday from 11 am to 4 pm, Sunday from 12 pm to 4 pm and is closed Tuesday and Wednesday. The remainder of the year, the museum is open Monday through Saturday from 9 am to 4:30 pm and Sunday from 12 pm to 4:30 pm. The museum is closed on New Year's Day, Easter, Thanksgiving and Christmas.
There is no fee to visit the grounds, a nominal fee to visit the museum is charged to visitors 15 and older.

Directions: Mastodon State Historic Site is located near Imperial Missouri off of I-55. From Exit 186/Imperial/Kimmswick take Imperial Main Street west and turn right (north) onto West Outer 55 Road. Turn left onto Seckman Road to go to the picnic area or continue West Outer 55 Road and turn left onto Charles J. Becker Drive, which will take you to the museum entrance.

GPS Coordinates
N  38°  22.759'
W 90°  23.082'

Learn more about the Imperial and Kimmswick areas.


Mastodon State Historic Site - Official site maintained by the Missouri Department of Natural Resources.

Hiking at Mastodon State Historic Site
Limestone Hill Trail
1.75 miles
This trail is rated Strenuous This loop trail shares a trailhead with Spring Branch Trail located in the picnic area just to the west of the visitors center. Before the Limestone Hill Trail splits off it passes by the Bollefer Springhouse. Use caution when crossing Seckman Road; vehicles are often fast and frequent. The Limestone Hill Trail is a steep and rugged hike with challenging slopes and rough terrain leading you along the base of a limestone bluff, up a hill through an oak hickory and cedar forest and across the hilltop with scenic views of Seckman Valley. There are several benches and overlooks along the trail.
Spring Branch Trail
Barrier Free
0.8 miles
This trail is rated Easy This trail shares a trailhead with the Limestone Hill Trail located in the picnic area just to the west of the visitors center and offers a leisurely hike through a portion of the Rock Creek bottomland. The packed gravel surface is manageable for wheelchairs and strollers to follow a small stream flowing from the Bollefer Spring past remains of the Bollefer springhouse, built in 1837. The trail loops through a young forest and winds along Rock Creek before returning to the trailhead.
Wildflower Trail
0.4 miles
This trail is rated Moderately Strenuous This trail guides visitors down a series of stairs to the Kimmswick Bone Bed, where scientists first discovered evidence that American mastodons coexisted with humans 12,000 years ago. The trail passes the Callison Memorial Bird Sanctuary, a wildflower area, crosses an old limestone quarry, and goes down a limestone bluff and talus slope to the bone bed. Past the bone bed, the trail continues to a small foot bridge over a spring that actively flows after heavy rain. The trail then heads uphill through a dense oak forest to the limestone bluff and then back to an intersection that leads visitors back to the museum or to Callison Memorial Bird Sanctuary.
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