List of national natural landmarks in Colorado

This is a list of National Natural Landmarks in the U.S. state of Colorado.

There are 16 National Natural Landmarks in Colorado, one of which extends into Wyoming. They cover areas of geological, biological and historical importance, and include lakes, mountains, rock formations and numerous fossil sites. The landmarks are located in 14 of the state's 64 counties. Four counties each contain all or part of two NNLs, while two landmarks are split between two counties. The first two designations, Slumgullion Earthflow and Summit Lake, were made in 1965, while the most recent designation, Sulphur Cave and Spring, was made in 2021.^[1]^[2]^[3] Natural Landmarks in Colorado range from 60 to 380,000 acres (24.3 to 153,780.5 ha; 0.1 to 593.8 sq mi) in size. Owners include private individuals and several municipal, state and federal agencies.^[4]

The National Natural Landmarks Program is administered by the National Park Service, a branch of the Department of the Interior. The National Park Service determines which properties meet NNL criteria and, after notifying the owners, makes nomination recommendations. The Secretary of the Interior reviews nominations and, based on a set of predetermined criteria, makes a decision on NNL designation or a determination of eligibility for designation. Both public and privately owned properties can be designated as NNLs. Owners may object to the nomination of the property as a NNL.^[5] This designation provides indirect, partial protection of the historic integrity of the properties via tax incentives, grants, monitoring of threats, and other means.^[6]

National Natural Landmarks

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Big Spring Creek

Garden Park Fossil Area

Garden of the Gods

Hanging Lake

Indian Springs Trace Fossil Site

Lost Creek Scenic Area

Morrison-Golden Fossil Areas

Raton Mesa

Roxborough Park

Russell Lakes

Sand Creek

Slumgullion Earthflow

Spanish Peaks

Sulphur Cave and Spring

Summit Lake

West Bijou Site

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Colorado National Natural Landmarks (clickable map)

#	Name	Year	Location	County	Ownership	Description
1	Big Spring Creek	2012	37°46′00″N 105°37′30″W / 37.7666667°N 105.6250000°W / 37.7666667; -105.6250000 (Big Spring Creek)	Saguache	Federal	Unique spring-fed creek fed by an unconfined aquifer, creating a rare animal- and plant-supporting wetlands in a generally arid area. Part of Great Sand Dunes National Park and Preserve.^[7]
2	Garden of the Gods	1971	38°52′04″N 104°53′28″W / 38.8677690°N 104.8910877°W / 38.8677690; -104.8910877 (Garden of the Gods)	El Paso	Municipal	The site showcases the lithologic character of sedimentary rocks, as well as providing a habitat for North American honey ants and excellent viewing opportunities for several bird species.^[8]
3	Garden Park Fossil Area	1973	38°32′06″N 105°13′18″W / 38.5349959°N 105.2216545°W / 38.5349959; -105.2216545 (Garden Park Fossil Area)	Fremont	Federal	Internationally recognized paleontological site renowned for finds of dinosaur, fish, crocodile, turtle and mammal fossils. Located on Bureau of Land Management land.^[9]
4	Hanging Lake	2011	39°36′05″N 107°11′30″W / 39.6013883°N 107.1917138°W / 39.6013883; -107.1917138 (Hanging Lake)	Garfield	Federal	Travertine deposition-formed lake with substantial hanging garden plant life and minimal human alteration, unique in the region. A part of White River National Forest.^[10]
5	Indian Springs Trace Fossil Site	1979	38°22′03″N 105°29′07″W / 38.3674977°N 105.4852759°W / 38.3674977; -105.4852759 (Indian Springs Trace Fossil)	Fremont	Private	Best North American location for animal trace fossils from the Ordovician period.^[11]
6	Lost Creek Scenic Area	1966	39°16′07″N 105°28′05″W / 39.268611°N 105.468056°W / 39.268611; -105.468056 (Lost Creek Scenic Area)	Park, Jefferson	Federal	Located in Pike National Forest, with extensive rock formations, including gorges, ridges and spires, and stream channels that meander between above- and under-ground.
7	Morrison-Golden Fossil Areas	1973	39°40′52″N 105°11′33″W / 39.68100°N 105.19238°W / 39.68100; -105.19238 (Morrison-Golden Fossil Areas)	Jefferson	County, private	Site of major paleontological importance, unique for fossil footprints of reptiles, birds, and mammals. The site was expanded in 2011 to include the 19-acre (7.69 ha; 0.03 sq mi) Parfet Prehistoric Preserve in the city of Golden.^[12]
8	Raton Mesa	1967	37°05′52″N 104°27′46″W / 37.0978686°N 104.4627319°W / 37.0978686; -104.4627319 (Fishers Peak)	Las Animas	State, private	Protected by a thick lava cap, Raton Mesa has resisted the extensive erosion and weathering that has affected surrounding areas, providing an extreme contrast in geography.
9	Roxborough State Park	1980	39°25′45″N 105°04′06″E / 39.42907°N 105.06841°E / 39.42907; 105.06841 (Roxborough Park)	Douglas	State	Site showcases typical Colorado Front Range sedimentary strata, as well as erosion of Fountain Formation sandstone in unusual patterns, extensive fossil remains and unusual plant populations.
10	Russell Lakes	1975	37°56′41″N 106°07′12″W / 37.9448092°N 106.1199637°W / 37.9448092; -106.1199637 (Russell Lakes)	Saguache	Federal, private	Colorado's largest remaining bulrush marsh, now rare in the southern Rocky Mountains. Provides habitat for extensive flora and fauna, especially waterfowl.
11	Sand Creek	1984	40°59′45″N 105°46′05″W / 40.9957404°N 105.7681064°W / 40.9957404; -105.7681064 (Chimney Rock)	Larimer	Federal, state, private	Shared with Wyoming, the site is one of North America's most impressive occurrences of cross-bedded sandstone and "topple blocks". Also a site of paleontological and biological significance.
12	Slumgullion Earthflow	1965	37°59′55″N 107°14′42″W / 37.9986086°N 107.2450542°W / 37.9986086; -107.2450542 (Slumgullion Earthflow)	Hinsdale	Federal, private	A major example of the geologic process of mass wasting, a large flow of volcanic rock traveled from mountainside to valley to form Lake San Cristobal. The same process is occurring again, slowly covering the existing flow. Located on Bureau of Land Management land.
13	Spanish Peaks	1976	37°22′32″N 104°59′37″W / 37.3756661°N 104.9936861°W / 37.3756661; -104.9936861 (West Spanish Peak)	Huerfano, Las Animas	Federal, private	Located in San Isabel National Forest, the site is an exceptional illustration of over 500 igneous dikes, many exposed, formed when molten igneous rock is forced into a fault before hardening.
14	Sulphur Cave and Spring	2021	40°29′01″N 106°50′24″W / 40.4836973°N 106.8401306°W / 40.4836973; -106.8401306 (Sulphur Cave and Spring)	Routt	Municipal	Located in the Howelsen Hill Ski Area of Steamboat Springs, the site is a superb example of bacterially-mediated sulfuric acid speleogenesis. The cave contains many uncommon cave features, such as biovermiculations and snottites.
15	Summit Lake	1965	39°35′54″N 105°38′40″W / 39.5983532°N 105.6443243°W / 39.5983532; -105.6443243 (Summit Lake)	Clear Creek	Municipal	At almost 13,000 feet (4,000 m), the site contains an excellent example of alpine tundra in the contiguous US. Some of the plants that survive in this microclimate are usually found only in the Arctic Circle.
16	West Bijou Site	2016	39°40′52″N 104°44′09″W / 39.68100°N 104.73588°W / 39.68100; -104.73588 (West Bijou Site)	Arapahoe	Private	Part of the Plains Conservation Center, the site contains fossil and mineral evidence detailing the Cretaceous–Paleogene boundary, the Earth's most recent mass extinction event.^[2]