Established on May 18, 1962, the National Natural Landmarks Program identifies and advocates for the conservation of sites containing both biological and geological resources. Stewart Udall, the then Secretary of Interior for the United States, incorporated the program to encourage voluntary preservation of areas that exhibit the United States natural history, as well as offer support. The NNL Program has supervision from the National Park Service. The State of Colorado, nicknamed The Centennial State, has a total area of 104,094 square miles, ranking it eighth largest in the US. The highest point in Colorado is Mount Albert with an elevation of 14,440 feet. Within the state, there are 14 National Natural Landmarks, and one shared with the State of Wyoming.
15. Big Spring Creek
Located in the Great Sand Dunes National Park and Preserve, the federal government owned Big Spring Creek covers an area of 440 acres. The spring-fed creek arises from groundwater from an unconfined aquifer. The wetlands supports plants and rare species in the arid area of Saguache County in Colorado. In 2012, the National Park Service designated the Big Spring Creek as a National Natural Landmark for its patterns of geological and hydrological nature.
14. Garden of the Gods
Garden of the Gods covers an area of 862 acres within the Garden of the Gods Park in Colorado’s El Paso County. The Colorado Springs home rule municipality owns and manages the park. Garden of the Gods received designation as a National Natural Landmark in 1971. The site has geological formations of sedimentary rocks vertically lifted by the same forces that produce the Rocky Mountains. The landmark contains an uncommon honey ant species discovered in 1879. The site is home to swallows, canyon wrens, and white-throated swifts.
13. Garden Park Fossil Area
Owned by the Federal government, the Garden Park Fossil Area is 3,209 acres in size and located in Fremont County. Designated as a National Natural Landmark in 1973, the site is North America’s most significant location for Late Jurassic age fossils. In the late 1800s, the area generated worldwide interest. Archeologists found three complete Stegosaurus skeletons at the site, as well as remains including specimens of Diplodocus and Ceratosaurus. In 2013, the government expanded the landmark’s boundary.
12. Hanging Lake
Formed by travertine deposition, Hanging Lake is in Glenwood Canyon in Garfield County. The lake was designated as a National Natural Landmark in June 2011 and covers an area of 72 acres. Hanging Lake is owned by the federal government. The Hanging Lake’s water turquoise colors come from dissolved carbonate minerals. The landmark supports the largest hanging garden plant community and is a popular destination for hiking in the state. Ecological disruption threatens Hanging Lake due to the traffic of more than 131,000 visitors every year. There is a prohibition of swimming and dogs in the lake.
11. Indian Springs Trace Fossil
The privately owned Indian Springs Trace Fossil Natural Area in Colorado’s Fremont County was designated as a National Natural Landmark in 1979. The site cover an area of 113 acres. The landmark has 25 different trace fossil types including trilobites, brachiopods, and horseshoe crab all set in Harding Formation rock. Owners of the site conduct tours in the Gold Belt Byway location. The fossils show the ancient Ordovician animal life movements and markings dating more than 450 million years ago.
10. Lost Creek Scenic Area
Located in the Lost Creek Wilderness, the Lost Creek Scenic Area covers a total area of about 26 square miles in both Park and Jefferson counties in Colorado. The scenic area, created in 1963, received designation as a National Natural Landmark in 1966. The landmark is part of the Pike National Forest and has spires, narrow gorges, and ridges.
9. Morrison-Golden Fossil Areas
Designated as a National Natural Landmark in 1973, the sites cover an area of 80 acres. The Morrison-Golden Fossil Areas reveal bones of crocodiles and dinosaurs and reptile tracks as well as other fossils including plants. In June 2011, the landmark’s boundary was expanded. Within the Morrison Fossil Area, there is Dinosaur Ridge, which is a world-renowned dinosaur fossil location. The Dinosaur Ridge Exhibit Hall displays dinosaurs found at the landmark. The combination of the Dinosaur Ridge and another track created the Morrison-Golden Fossil Areas. Ownership of the sites is both by the county and private individuals.
8. Raton Mesa
Raton Mesa’s highest part which covers an area of 4,183 acres became a National Natural Landmark in 1967. The landmark is within the Las Animas County in Colorado and owned by the state and private individuals. A thick lava cap preserves the mesa which has resisted the effects of extensive weathering and erosion in the surrounding areas. Raton Mesa is part of a region that produces natural gas and coal known as the Raton Basin.
7. Roxborough State Park
Established in 1975, the Roxborough State Park is in Douglas County in Colorado. The park has an area of 743 acres and owned by the state. The site has unusual erosion patterns, fossil remains, and fine exposures of hogbacks. Due to its geological formations and ecological systems, the site gained recognition as a National Natural Landmark in 1980. The number of archaeological locations makes the park a National Cultural District and a State Historical Site.
6. Russell Lakes
Russell Lakes in Saguache County, Colorado was designated in 1975. The landmark covers an area of 2,306 acres and is owned privately and by the Federal government. The Russell Lakes, which is a Colorado Natural Area, is an extensive bulrush marsh. The area is a waterfowl breeding site and supports plenty of flora and fauna.
5. Sand Creek
Sand Creek displays a great example of topple blocks and cross-bedded sandstone. The Sand Creek stream flows between Larimer County in Colorado and Albany County in Wyoming. In 1984, the border region between the states of Colorado and Wyoming, where the stream crosses the border, was designated as a National Natural Landmark. Ownership of the landmark is private, as well as both federal and state and covers an area of 5,118 acres.
4. Slumgullion Earthflow
In Hinsdale County, Slumgullion Earthflow covers an area of 800 acres and displays the geologic process of mass wasting. 700 years ago, a slow-moving landslide created a mass measuring 4 miles in length and 2,000 feet wide. Owned privately and by the federal government, the Slumgullion Earthflow was designated as a National Natural Landmark in 1965.
3. Spanish Peaks
The Spanish Peaks, named Huajatolla by the Ute Indians, are within the San Isabel National Forest covering an area of about 59 square miles in both Huerfano and Las Animas counties. The Spanish Peaks was designated as a National Natural Landmark in 1976. The site is owned both privately and by the Federal government, and has more than 500 exposed igneous dikes.
2. Summit Lake
Summit Lake is within the Summit Lake Park and covers an area of 160 acres. The region is a habitat for rare alpine-arctic plants at an elevation of about 13,000 feet. Often referred to as the United States highest lake, the Summit Lake is in Clear Creek County and was designated as a National Natural Landmark in 1965.
1. West Bijou Site
In both Arapahoe and Elbert counties in Colorado, the privately owned West Bijou Site covers an area of 7,613 acres. The National Park Service designated West Bijou Site as a National Natural Landmark in November 2016. Wild pronghorns are a feature on the landmark. The site has Cretaceous and Paleogene fossils, iridium anomaly, shocked quartz, and magnetostratigraphy. The area supports a variety of rare and common wildlife and plant species.