The River and its Geology
The Upper Missouri River landscape contains remarkable geologic land formations that have remained unchanged since first recorded in 1805 by Lewis and Clark’s Corps of Discovery expedition. However, this landscape was vastly different eons ago. About 90 million years ago, wide oceans, volcanoes, and dinosaurs existed in what is now Montana. Rivers continually carried sediment into the vast interior sea. These sediments of mud and silt were laid down in layers on the ocean floor. Over great periods of time, these sediments were compressed and formed into sedimentary rocks.
Next came the glaciers. They pushed south into present-day Montana and forced the Missouri River into a new channel by carving through stone and sediment to re-route the flowing waters. As more time passed, flowing magma from prehistoric volcanoes hardened and formed into igneous rock while uplifts occurred on the ocean floor, causing the interior seaway to drain. These newly exposed landforms have been and still are subjected to rain, snow, wind, ice, and piercing heat. These climatic forces shaped the sedimentary and igneous rocks into extraordinary cliffs, canyons, pillars, and spires near the water’s edge and continue to do so. Shonkinite is a widely known type of igneous rock found in the Missouri River, and fossilized remains of marine reptiles, crocodiles, and dinosaurs are often discovered in the area.
In 1976, Congress designated a 149-mile stretch of the Missouri River through northcentral Montana as wild and scenic. In 2001, President Clinton established the Upper Missouri River Breaks National Monument. “Breaks” refer to the rugged and remote valleys, badlands, and coulees that surround the Upper Missouri River, a wondrous landscape carved centuries ago by geologic and other natural forces.
The Missouri Breaks and Missouri River showcase a vivid variety of plant life. Native Americans used many species for medicinal purposes, including rubber rabbitbrush, prairie coneflower, and creeping juniper. They used other plants for food, including silver buffaloberry and chokecherry. Plants in this area need to be drought-resistant, because the Breaks and surrounding region receives less than 12 inches of precipitation during the year. Plants in this region have adapted to the harsh conditions in two primary ways. Some have long root systems for finding water while others, including prickly pear cactus and yucca, store moisture in their fleshy leaves for the drier times.
Many of these plants have been planted around the Missouri Breaks Interpretive Center, offering visitors an outdoor education about the region’s colorful vegetation.
Coyote display in center
The Upper Missouri River Breaks region provides habitat for an array of animals. Pronghorn, also known as antelope, are often seen in the region among the sagebrush and in open areas. These fleet-footed creatures can run more than 60 mph for short distances, making them the fastest land animal in North America. Beaver, mule deer, jackrabbits, and coyotes can also be seen. Beaver pelts and castor glands served as important trade items during the 1800s. Men wore hats made of beaver pelts and perfume was made from the castor glands. Beaver were quickly depleted as trappers and traders filled the nation’s need for fashion. People’s tastes changed in the mid-1800s with the creation of silk hats and the discovery of other sources of oil for perfume. Beavers rebounded since that time and now serve as an important check in the ecological balance of river and stream systems.
Many different birds make their home along the river and on the nearby prairies. Greater sage-grouse, sharp-tailed grouse, and meadowlarks live on the prairies and in the coulees, while several species of birds, such yellow warblers, hairy woodpeckers and yellow-headed blackbirds, can be found along the riparian areas of the river. Raptors, including bald and golden eagles and red-tailed hawks soar overhead while prairie and peregrine falcons rip through the sky in search of prey. American white pelicans, Canada geese, and numerous ducks dabble and dive along the river’s edge. Reptiles and amphibians, including the rattlesnake, gopher snake, turtles, toads, and frogs add to the diversity of wildlife found in the area. Floating the river, you may encounter the awesome big game species of mule deer, bighorn sheep, and elk. A variety of fish live in the waters of the Upper Missouri, including the endangered pallid sturgeon and one of the last remaining paddlefish populations in the United States; both of these species have been in these waters since the age of dinosaurs. Did you know the pallid sturgeon and the paddlefish can live to be 60 years old?
So bring your binoculars and your field guides whether you are floating the river or simply driving through the area and the enjoy bounty of wildlife of the Upper Missouri River area!
Enjoying the River and the Monument
The Upper Missouri River and the breaks offer a special haven for visitors. Hiking, camping, fishing, floating, and nature watching are just a few of the activities that can be enjoyed. Maps and guidelines are available.
For information on floating the Upper Missouri River, visit
For information on the Upper Missouri Breaks National Monument, visit