Idaho contains late Piocene and Pleistocene fossils--the most recent period of mammals. During the Paleozoic Era (230 million years ago), Idaho was a shallow sea, and the Paleozoic fossils discovered in Idaho comprise trilobites, crinoids, sea stars, ammonites and sharks. Although fossil hunting is not as prolific as in Montana, several small dinosaurs were uncovered along the eastern Idaho-Wyoming border. The best-known fossil discovery being the Hagerman horse--the state fossil of Idaho.
Hagerman Fossil Beds National Monument
Considered one of the most valuable fossil beds, due to the completeness of fossils found, the Hagerman horse quarry area was once a large freshwater lake (Lake Idaho) where animals congregated for food and water. Examination of fossil evidence indicates the climate and vegetation evolved from a warm, humid region to a high-desert plateau. Deemed a national park, the Hagerman Fossil Beds National Monument, including the Hagerman horse quarry area, is maintained by the U.S. National Park Service. A visitors' center, a few isolated trails and viewpoints offer visitors several educational interests as well as learning courses, college credit programs, and staff guided tours into safe areas of the quarry.
Unlike other national parks, the Hagerman Monument is a learning center for paleontological research and education. Over 40,000 fossil specimens have been recovered and restored with many on display in museums throughout the country. The area is closed to the public due to hazardous landslide conditions; however, these landslides expose thousands of fossils every year, keeping the monument staff busy digging and protecting new finds.
Clarkia Fossil Formation
Prehistoric Clarkia offered a similar climate and ecology similar to modern Florida. In Clarkia, Idaho, 15 million-year-old fossil beds contain the remains of plants and animals; anoxic conditions slowed decomposition, allowing preservation of an organisms' soft tissue--normally absent from the fossil record. This extensive collection of compression fossils allows scientists to conduct detailed studies of ancient plants (paleobotany) and climates. Clarkia contains exceptionally well-preserved specimens of insects, fish and leaves, including the Bald cypress and Dawn redwood. The Clarkia Fossil Bowl is open in summer for public digging.
Oviatt Creek Fossil Beds
Located about 50 miles east of Moscow, Idaho, southwest of the Elk River, the Oviatt Creek Fossil beds are easily accessible by car (in good weather). Many fossils are visible at the surface; however, exposure to air and oxygen cause the specimen details to deteriorate. Oviatt Creek fossils contain different types of ancient plant matter, including leaves, stems, seeds and conifer cones-- even insects.
For more information, contact the Oviatt Creek Fossil Beds through the Clearwater National Forest Supervisor's Office 208-476-4541 or the Palouse Ranger District 208-875-1131.
Located west of St. Charles is the largest limestone cave in Idaho. Ninety-minute tours take you through nine separate chambers filled with fantastic formations and fossils of preserved tropical plants and marine life; however, collection of fossils is prohibited in the cave. Developed by the federal government in 1930 via the Works Progress Administration, interior paths, steps, trails and railings were installed. The U.S. Forest Service, as part of the Cache National Forest, manages Minnetonka Cave.
Fossils with the organic matter intact are called compression fossils. Original cell walls are retained and visible under a microscope. Compression fossils reside in deep layers of rock, far from air and oxygen exposure.
Because of their archeological importance, fossils may not be collected without a permit. For more information on fossil hunting regulations in Idaho, contact the Idaho Chamber of Commerce.