Florissant Fossil Beds National Monument

A view at Florissant Fossil Beds National Monument

An early settler from Florissant, Missouri named this area after his hometown. 34 to 35 million years ago, this valley was dominated by Lake Florissant, averaging 1 mile in width and stretching 12 miles through an ancient forested valley. Lush ferns and shrubs lived beneath redwoods, pines, cedars and a mixed-hardwood forest. There were thousands of insects in the humid climate. Mollusks, fish, birds and mammals lived in or around the lake. Again and again volcanic mudflows blanketed parts of the valley, one of them responsible for the creation of the lake. Every time the volcano erupted it showered the area with tons and tons of ash and pumice. Each rainfall washed the fine ash into the lake where it slowly covered the remains of creatures that died and sank to the bottom. Eventually those sediments were compacted and became shale, fossilizing the buried remains.

Today, Florissant Fossil Beds National Monument preserves this internationally renowned site. More than 50,000 specimens have been collected by paleontologists working here. As much as a lot of that ancient lake life is preserved here, very little of the other forms of life that inhabited the area are preserved: Unless a bird or mammal died in or near the lake, its chances of preservation were very slim.

A historic barn at Florissant Fossil Beds National Monument
Map of Florissant Fossil Beds National Monument

The remains of prehistoric plants and animals found here are relatively young in geologic terms. The fossils found at Florissant have much to say about life in the late Eocene Epoch, about 30 million years after the last of the dinosaurs and about 33 million years before the first humans. Most of the fossils found here are studied and kept at various universities and museums, with a few displayed in the park visitor center. Unfortunately, many others were taken as souvenirs over the years and the knowledge they may have imparted was lost. The park now protects millions of undisturbed fossils and allows a limited number to be excavated for study each year.

Fossils of more than 140 species of plants have been found at Florissant. These consist mostly of leaves but twigs, cones, seeds, flowers and pollen grains have also been found. There are also massive petrified stumps of giant redwood trees where volcanic mudflows buried them millions of years ago. The record in the stone suggests that the ancient forest was unlike any now in Colorado. Trees and shrubs grew here whose closest living descendants are now found in the southeastern United States, Mexico and China.

While insects are usually too fragile to be preserved as fossils, the fine volcanic ash did such a good job here that many thousands of insect fossils have been recovered from the shale. More than 1400 species have been described from the findings so far. The fossils show that the insects of 34-35 million years ago were very similar to today''s, however, many types that are found here no longer exist in Colorado. Some, like the tsetse fly, no longer live in North America and many others are extinct.

What's left of the bottom of the ancient lake bed at Florissant Fossil Beds National Monument

Fossils are studied in the context in which they are found and as one element in a community of organisms. Some of the insect fossils are found coupled with the leaves that they lived on. Because of this relationship, every fossil can serve as a key to unlock ancient knowledge. As most of the remains found here date from the Eocene Epoch, Florissant Fossil Beds serves as a wonderful repository of information. In the Eocene Epoch, mammals emerged as the dominant land animals on the planet. They also took to the air and the sea. The many variations included some of the earliest giant mammals. The fossil record reveals many mammals unlike anything seen today. However, as time went on and evolution continued, the forest plants, freshwater fish and insects became much more like those we know now.

From Labor Day to Memorial Day, Florissant Fossil Beds National Monument is open from 9 am to 5 pm daily except on Thanksgiving, Christmas and New Year''s Days. From Memorial Day to Labor Day the hours are 8 am to 6 pm, every day. Entry fees: $3 per person for ages 16 and up, good for seven days from date of purchase. Younger folks get in free. Fees can only be paid by cash or check, no credit or debit cards. Florissant Fossil Beds National Monument is a day-use only property, no camping is allowed. The Monument offers 14 miles of hiking trails including two self-guided trails that begin in the outdoor exhibit area behind the Visitor Center. There is a picnic area at the Visitor Center and another on Lower Twin Rock Road.

Plant fossils found at Florissant Fossil Beds
Plant fossils found at Florissant Fossil Beds
Some of the insect fossils found at Florissant Fossil Beds
Insect fossils

Fossil images and small map from the Florissant Fossil Beds Official Map and Guide
Other photos courtesy of TheArmchairExplorer, CCA-by-SA 4.0 License