Last updated: September 25, 2026
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Valley Forge Fossil Day 2026
NPS Graphic / G. Purifoy
Celebrating Ice Age Fossils
In honor of the 17th anniversary of National Fossil Day, Valley Forge National Historical Park is celebrating the amazing Ice Age fossils of Valley Forge with a day of interactive, family-friendly activites and special programs.
Learn about mastodons, saber-toothed cats, giant ground sloths, and lots of other incredible critters that walked the ancient landscape of Valley Forge hundreds of thousands of years before George Washington and the Continental Army ever set foot here.
When: Saturday, October 17, 2026 between 12 noon and 4 pm
Where: Visitor Center at Valley Forge
Photo by Justin Tweet, used with permission of Ted Daeschler/Academy of Natural Sciences of Drexel University.
The Port Kennedy Bone Cave (in what is now Valley Forge National Historical Park) was discovered during limestone quarrying in the 1870s and explored through the 1890s. Around 1,200 fossil specimens were removed, including fossilized bones from Ice Age (Middle Pleistocene) mammals like bears, giant sloths, American cheetahs, saber-toothed cats, mastodons, and many more!
Today, most of the fossils are in the collections of the Academy of Natural Sciences of Drexel University in Philadelphia and the American Museum of Natural History in New York.
Learn more >
NPS Photo / G. Purifoy
See Some Fossils!
12 noon to 4 pm in the Visitor Center at Valley Forge
Meet paleontologists from the Academy of Natural Sciences of Drexel University! Explore real fossils, casts of fossils, and how these animals ended up together in what is known as the Port Kennedy Bone Cave.
NPS Image
Be a Junior Paleontologist
12 noon to 4 pm in the Visitor Center at Valley Forge
Pick up a copy of the Junior Paleontologist Activity Booklet in the Visitor Center at Valley Forge! Complete the activities in the booklet and show it to a ranger in the visitor center to earn a special Junior Paleontologist badge. (While supplies last!)
Fossil Day Science Talks
An Entrance to Former Worlds: the Cave, Landscape, and Geologic History of Valley Forge
1 pm in the Meeting Room at Valley Forge
John A. Sime, PhD
Lecturer, University of Pennsylvania
This is a story about how five-hundred-million-year-old rocks, which formed beneath ancient seas, came to entomb five-hundred-thousand-year-old fossils, that recorded the demise of extinct land mammals.
The Port Kennedy Bone Cave: Site Discovery, Excavation, and Significance
2:15 pm in the Meeting Room at Valley Forge
Sean Walsh-Haehle
Park Guide, Valley Forge National Historical Park
Come learn about the discovery and excavation history of Valley Forge's very own ice-age fossil site.
The Bone Wars: A Story of Brutal Competition in Early Paleontology
3:30 pm in the Meeting Room at Valley Forge
Liam O'Donnell
Science Educator
Edward Drinker Cope, who analyzed fossils found at the Port Kennedy Bone Cave, is better known for his role in the "Bone Wars," a period of ruthless competition with Othniel C. Marsh that led to lots of underhanded dealings as well as scientific discovery.
NPS Graphic / G. Purifoy
Evening Campfire Talk - Port Kennedy Bone Cave
7 pm at Muhlenberg's Brigade
What was life like in this part of the world 750,000 years ago? Fossils found right here in Valley Forge give us clues! Join us for a discussion about the history of this fossil excavation, and about the Ice Age animals that once made this place their home.
What to Bring: Flashlight, blanket, jacket, camp chair.
Weather: The program will be canceled for rain, call 610-783-1000, option 1 before 5 PM to check on the status of the program.