Florissant Fossil BedsNational Monument

Florissant’s Geology

What is the National Park Service?

The National Park Service preserves, unimpaired, the natural and cultural resources and values of the National Park System for the enjoyment, education, and inspiration of this and future generations.

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Ranger Walks

Ranger Talks

Self-Guided Trails

Park Services

Environmental Education

Wildlife Management

Paleontological Resources

First Responders

Protections Rangers

Fire Management – wildfire and structural

Cultural Resource Management

Wildland Management

About 35 miles west of Colorado Springs, CO lies the Florissant valley. Florissant is a French word meaning flowering or blooming.

The valley is also home for wildlife, such as Golden Eagle which nests and raises young here each year.

A large herd of elk spends the winter in the valley. Squirrels, coyotes, foxes and black bears also call the Florissant Valley home.

But 35 million years ago, the environment here was very different from what you see today. Thick, lush vegetation grew in a warm, humid, almost subtropical climate.

The area was home to a variety of animals then. Some, like the small horse and opossum, we would recognize today. Others would be unfamiliar to us, like the brown animal with white spots, an oreodont. It was the size of a sheep, with a head like a pig and a body like a dog.

When we think of fossils we often picture giant dinosaurs. There were giants living in the Florissant valley 34 million years ago, but they were giant redwood trees, sequoia affinis, an extinct relative of today’s California coastal redwood.

Some of these trees grew over 300 feet tall, 3 to 4 times the height of today’s forest, and were up to 45 feet around at the base. Notice the people in the lower right hand corner of this picture of a redwood forest today.

Under the redwood canopy grew a lush forest with a variety of hardwood trees, green plants, palm trees and ferns.

A giant volcano towered over the Florissant valley millions of years ago. It was located about 18 miles to the southwest, near the town of Guffey. It may have been even bigger than Pikes Peak is today.

About 34 million years ago the volcano began to erupt. It sent up a huge column of ash. It may have had snow which began to melt.

The ash mixed with the melted snow and water formed a tremendous mud flow that swept down the sides of the volcano into the valleys below. These rapidly moving mudflows are called lahars.

They cooled and formed hard volcanic tuffs.

The thick gray mud covered and surrounded everything in its path. The redwood trees along the stream banks were surrounded in up to 15 feet of mud.

The tops of the trees gradually decayed away, while the stumps mineralized.

The petrification of the stumps occurred when ground water seeped up through the layers of tuff and penetrated into the buried wood.

Tree rings from both fossils and modern trees, are important because they allow scientists to determine the approximate age of the trees when they died and to learn about the climate that existed as the trees grew.

The water dissolved minerals in the tuff, mainly silica or quartz, and the minerals gradually replaced the cells of the trees. This process is called permineralization.

So where a giant redwood like this once grew………

…..we now find petrified stumps. Florissant Fossil Beds National Monument has some of the largest and finest petrified sequoia affinis trees in the world.

As the mud flows cooled and hardened around the sequoia trees, mudflows also formed a dam at the south end of the valley. Water from the valley’s streams backed up and eventually created a lake.

Ancient Lake Florissant was about 12 miles long, 4 miles at it’s widest point, between 30 and 60 feet deep. When the lake first formed nothing was growing on the 15 foot thick tuff surrounding the lake.

Within a few months after volcanic eruptions, new plants slowly began to grow back, because volcanic rock provides all the nutrients a plant needs except nitrogen. Moss provides its own nitrogen and becomes a seed bed.

Pioneering plants, able to grow in the sterile, organically poor soil, helped to build up nutrients which allowed other plants to grow and alter the environment even more.

Until eventually, over a long period of time, the forest was restored along the shores of the lake.

The volcano continued to erupt off and on for thousands of years, although these eruptions were probably not as powerful as the initial ones. Volcanic ash and poisonous gasses from these eruptions blew into the valley below.

In this diagram, drawn by a student, we see some of the ash fell into ancient Lake Florissant and settled in thin layers on the lake bottom, covering plants and insects that had died, and sealing them in.

Picture a passing oreodont walking along the shore of the lake and knocking a piece of this delicate fern in the lake. If it was covered quickly and completely by ash…….

……we might find it today as a fossil, a carbon preservation of the delicate frond.

Everything that we know about the ancient plants and animals that once lived in Florissant, like the giant redwood trees, comes from the pictures in stone found here.

Florissant is one of the important fossil sites in the world because of the incredible detail and abundance of the fossils. These fossils give us a detailed look at insects and plants of the past.

Delicate butterflies fell into the lake and are found preserved in amazing detail.

The only records we have of fossil butterflies in all of North America are found at Florissant Fossil Beds National Monument. More species of fossil butterflies are found here than at any other single fossil site in the world.

The detail of this wasp is apparent when examining the veins in the wings, the lines on the body, and even the tiny hairs on it’s legs.

The weight over a long period of time compressed these sediments into a rock called shale.

Additional mudflows from the dying volcano buried the lake sediments in a thick layer mixture of mud, sand, gravel, and rock.

Today we find the fossil bearing shale buried by this protective conglomerate mixture of mud and stone. This water resistant caprock is called breccia.

Countless eruptions of ash and layers of sediments carried by streams and erosion, eventually filled in ancient Lake Florissant.

The organisms were covered up and gradually disintegrated, but the carbon that was in their cells was fossilized in the layers of shale.

Opening the shale is similar to opening the pages of an ancient natural history book to read a story of life 34 million years ago.

Very slowly, the enviroment changed, becoming cooler and drier. The redwoods died out and other species of trees that were better adapted to the cooler, drier climate, grew in their place.

Today’s plant and animal community at Florissant is called the Montane ecosystem. In this habitat are ponderosa pine trees, firs, spruces, aspens, and many types of wildflowers which are able to survive the seasonal temperature variations and lack of rainfall typical in Florissant today.

The Ute people were nomadic, carrying their possessions with them when they moved. They did not disturb the fossils here. If you had to carry everything you owned with you, would you add rocks to your burden? And so the valley was virtually undisturbed until 1873.

This beautiful valley with its abundant wildlife and pictures in stone was well known to the Utes. Local legends say they may have called it the “Valley of the Shadows” because of the strange pictures of plants and insects they found in the thin gray rocks.

In 1873, fossils in the valley were “officially” discovered by non-native Americans when representatives of the US Geological Survey came to the valley on a mapping expedition. Their published report in 1874 did much more than just put the place on a map. They were the first to make an official report of the fossils.

Many families began coming to the Florissant valley to establish homes under the governments Homestead Act. This is the Horbek Homestead.

The discovery of the petrified stumps helped to increase the fame of the area. The Florissant valley became a popular vacation spot. Many visitors collected petrified wood and carbon fossils as souvenirs to take home with them.

Efforts to make this area a national monument began in 1920. It was not until 1969 that about a third of the ancient Lake Florissant was set aside for protection by the National Park Service.

While protection of the fossils is the main purpose of the National Monument, research and education are equally important.

Research into the past helps answer questions about climate change, the types of life once found here, and the geologic processes that created the fossils and continue to shape our environment today.

Education is another important purpose of Florissant Fossil Beds National Monument, both at the park and in the classrooms.

School groups visit the monument for field trips throughout the year.

Programs and tours for visitors are offered daily during the summer season