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Florissant Fossil Beds

National Monument


cover of park brochure

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Photo of petrified tree stump at Florissant Fossil Beds
Florissant Fossil Beds National Monument, Colorado

Today, Florissant Fossil Beds National Monument is a wonderland of meadows, forests, and wildflowers. Noting this brilliance, an early settler from Missouri gave this area his hometown's name since it means "flowering" in French. Yet 34 to 35 million years ago a description would tell another tale. Lake Florissant, stretching 15 miles through an ancient forested valley, dominates the scene. Lush ferns and shrubs thrive under towering redwoods, cedars, pines, and a colorful mixed hardwood forest of maples, hickories, elms, and oaks. In this warm, humid climate, thousands upon thousands of insects crawl, fly, and buzz about. Fish, mollusks, birds, and mammals inhabit the lake and its shores.

Nearby, a volcano rumbles. In the past, volcanic mudflows blanketed parts of the forest surrounding Lake Florissant, killing entire trees. Now as the volcano again erupts violently, the devastation is widespread. The exploding volcano showers the countryside with millions of tons of ash, dust, and pumice. Caught in this deadly cloud, insects, leaves, fish (anything that cannot escape) die, and many fall to the lake bottom, where they are buried. These eruptions occur again and again for perhaps as long as 700,000 years. Each time, fragments of life are trapped in a layer of volcanic sediments at the bottom of the lake. Eventually these sediments become a finely layered shale and transform the buried plant and animal life into fossils.

Florissant Fossil Beds National Monument preserves this site. The fossil beds are internationally renowned for the variety and number of fossils, particularly of insects and plants, they have yielded since their discovery in the late 1800s. Paleontologists have collected more than 60,000 specimens for museums and universities around the world. These fossils reveal, in remarkable detail, what life of so long ago was like. Ever so fragile and a tiny creature as a butterfly may be preserved as a fossil that clearly shows its antennae, legs, hairs, and the pattern of its wings. Massive petrified redwood stumps are evidence that ancient life here had its giants, too. Yet, little remains of other ancient Lake Florissant life. Fossil bones, teeth, shells, and feather impressions reveal the existence of mollusks, fish, birds, opossums, mesohippus (an ancestor of the modern horse), and oreodonts (extinct pig-like animals). But unless a mammal or bird actually died in or near the lake, its chances of preservation were very slim. Future scientific explorations promise to unearth more of Florissant's "buried treasures."

Fossils of Ancient Lake Florissant
The rich deposits discovered at Florissant Fossil Beds give us an unusually detailed look at life in an ancient North America. These impressions of prehistoric plants and animals are relatively young in geologic terms. The Florissant fossils hint at what life may have been like about 35 million years ago during the close of the Eocene Epoch; approximately 30 million years after the age of dinosaurs and at least 33 million years before humans appeared.

Today most of Florissant's fossils are exhibited and studied at various museums and universities. A small number are displayed in the park visitor center. Others, unfortunately, have been taken as private souvenirs over the years; what valuable information they might have provided cannot be known, for each fossil is an irreplaceable piece in the puzzle of the past. Fortunately millions of other fossils in yet undisturbed portions of the fossil beds are now protected by the park.

fossil leaves Fossil Plants. Fossils of an incredibly diverse mix of more than 100 species of trees and other plants have been discovered at Florissant. Most commonly fossil leaves are found, but fossil twigs, seeds, cones, flowers, and pollen grains also occur. Like the insects, plant fragments have usually been preserved as lifesize, color-enhanced impressions. A quite different type of plant fossil found at Florissant consists of massive petrified stumps of redwoods and other trees. They stand today where they were buried by volcanic mudflows millions of years ago. The stumps turned to stone as minerals seeped into the wood and gradually crystallized within living tissue. The fossil record suggests that the ancient forest was not like any now in Colorado. In it grew many trees and shrubs whose closest living relatives are now found in widely scattered places such as the southeastern United States, Mexico and China.

fossil insectsFossil Insects. Insects are rarely preserved as fossils because they are so fragile. The the fine sediment that settled in Lake Florissant was finer than talcum powder and ideal for the delicate job of preservation. Thousands of insect fossils have been recovered from the fine-grained, fossil-bearing shales. An amazing number of insect species (more than 1,100) have been identified. The insects are usually preserved as exquisitely detailed impressions in the shale, colored brown or black by a thin residue of organic matter - all that remains of the actual living thing. Some insects look perfect, other are crushed, and some are just parts: a delicate wing, a headless body. The fossils indicate that insects 35 million years ago were much like those today. However, many types that once lived at Lake Florissant no longer inhabit Colorado. Some like the tsetse fly, are gone from North America. Others are wholly extinct.

park maps subheading

The General park map handed out at the visitor center is available on the park's map webpage.

For information about topographic maps, geologic maps, and geologic data sets, please see the geologic maps page.

photo album subheading

A geology photo album for this park can be found here.

For information on other photo collections featuring National Park geology, please see the Image Sources page.

books, videos, cds subheading

Currently, we do not have a listing for a park-specific geoscience book. The park's geology may be described in regional or state geology texts.

Please visit the Geology Books and Media webpage for additional sources such as text books, theme books, CD ROMs, and technical reports.

Parks and Plates: The Geology of Our National Parks, Monuments & Seashores.
Lillie, Robert J., 2005.
W.W. Norton and Company.
ISBN 0-393-92407-6
9" x 10.75", paperback, 550 pages, full color throughout

The spectacular geology in our national parks provides the answers to many questions about the Earth. The answers can be appreciated through plate tectonics, an exciting way to understand the ongoing natural processes that sculpt our landscape. Parks and Plates is a visual and scientific voyage of discovery!

Ordering from your National Park Cooperative Associations' bookstores helps to support programs in the parks. Please visit the bookstore locator for park books and much more.

geologic research subheading


For information about permits that are required for conducting geologic research activities in National Parks, see the Permits Information page.

The NPS maintains a searchable data base of research needs that have been identified by parks.

A bibliography of geologic references is being prepared for each park through the Geologic Resources Evaluation Program (GRE). Please see the GRE website for more information and contacts.

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NPS Geology and Soils Partners

NRCS logoAssociation of American State Geologists
NRCS logoGeological Society of America
NRCS logoNatural Resource Conservation Service - Soils
USGS logo U.S. Geological Survey

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Currently, we do not have a listing for any park-specific geology education programs or activities.

General information about the park's education and intrepretive programs is available on the park's education webpage.

For resources and information on teaching geology using National Park examples, see the Students & Teachers pages.
updated on 01/04/2005  I   http://www.nature.nps.gov/geology/parks/flfo/index.cfm   I  Email: Webmaster
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