Fossil Butte National Monument, in the ridges of southwest Wyoming, preserves what the National Park Service calls some of the best-preserved fossils in the world. They formed in and around an ancient freshwater lake — Fossil Lake — about 52 million years ago, in a warm, wet environment. The rock here holds fossil fishes, insects, plants, reptiles, birds, and mammals, including stingrays, turtles, and early horses. It's a quiet, deep-time RV destination off the beaten path.
At a glance
The facts worth checking before you roll out
Conservative, source-minded facts for planning your visit — always worth confirming against current conditions before you travel.
State
Wyoming
Managed by
National Park Service
Age
About 52 million years (Eocene)
Rock unit
Green River Formation
On the ground
The National Park Service describes the fossils preserved in the ridges of southwest Wyoming as some of the best-preserved in the world. They record ancient life from a warm, wet environment surrounding a freshwater lake roughly 52 million years ago — a place the park calls the 52-million-year-old Fossil Lake.
The variety is remarkable. The NPS lists fossil fishes, insects, plants, reptiles, birds, and mammals, and notes that the ancient ecosystem included stingrays, turtles, early horses, and varied vegetation. These specimens come from the Green River Formation, a rock unit known worldwide for the quality of its fossils.
The story here is still being written — the park notes it reveals more of the past with each fossil found. For an RV traveler, it's a peaceful, science-rich stop; confirm current visitor-center hours and access on the National Park Service site before you go.
Official sources
- National Park Service — Fossil Butte National Monument National Park Service
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