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19-665: It was designated a National Natural Landmark in 1976 as the only North American location of tritylodont fossils. Parts of the ridge in Utah are protected as part of the Bears Ears National Monument . The geologic formations involved in the east dipping strata of the fold include the Jurassic aged Navajo Sandstone , Kayenta Formation , Wingate Sandstone , Chinle Formation , Triassic Moenkopi Formation and Permian Organ Rock Formation . The structure

38-583: A permanent crater lake about 100 m (330 ft) in diameter at an elevation of 6,390 m (20,965 ft) on its eastern side. This is most likely the highest lake of any kind in the world. Due to their unstable environments, some crater lakes exist only intermittently. Caldera lakes in contrast can be quite large and long-lasting. For instance, Lake Toba ( Indonesia ) formed after its eruption around 75,000 years ago. At around 100 kilometres (62 mi) by 30 kilometres (19 mi) in extent and 505 metres (1,657 ft) deep at its deepest point, Lake Toba

57-492: Is a lake in a crater that was formed by explosive activity or a collapse during a volcanic eruption . Lakes in calderas fill large craters formed by the collapse of a volcano during an eruption. Lakes in maars fill medium-sized craters where an eruption deposited debris around a vent. Crater lakes form as the created depression, within the crater rim , is filled by water. The water may come from precipitation , groundwater circulation (often hydrothermal fluids in

76-750: Is rigorous: to be considered for NNL status, a site must be one of the best examples of a natural region's characteristic biotic or geologic features. Since the establishment of the NNL program, a multi-step process has been used to designate a site for NNL status. Since 1970, the following steps have constituted the process. Prospective sites for NNL designation are terrestrial and aquatic ecosystems; geological features, exposures, and landforms that record active geological processes or portions of earth history; and fossil evidence of biological evolution. Each major natural history "theme" can be further subdivided into various sub-themes. For example, sub-themes suggested in 1972 for

95-622: Is the surface expression of a deep fault along the east margin of the Monument Uplift. Traces of the Ancestral Puebloan culture can be found along the southern part of the ridge where it follows Chinle Wash . The Macomb and Hayden expeditions in 1869 and 1874–1876, respectively, were the first to publish maps and descriptions of this feature. The ridge and adjacent Butler Wash were given their current names in 1884, by P. Holmann. Numerous cliff dwellings are found along

114-688: Is voluntary. The legislative authority for the National Natural Landmarks Program stems from the Historic Sites Act of August 21, 1935 (49 Stat. 666, 16 U.S.C. 641); the program is governed by federal regulations. The NNL Program does not have the protection features of Section 106 of the National Historic Preservation Act of 1966. Thus, the designation of a National Natural Landmark presently constitutes only an agreement with

133-822: The National Park Service , U.S. Forest Service , Bureau of Land Management , Bureau of Reclamation , Fish and Wildlife Service , Air Force , Marine Corps , Army Corps of Engineers , Navy , and others. Some NNLs has been designated on lands held by Native Americans or tribes. NNLs also have been designated on state lands that cover a variety of types and management, such as forest , park , game refuge , recreation area , and preserve. Private lands with NNLs include those owned by universities, museums , scientific societies, conservation organizations, land trusts , commercial interests, and private individuals. Approximately 52% of NNLs are administered by public agencies, more than 30% are entirely privately owned, and

152-519: The U.S. Virgin Islands . The National Park Service administers the NNL Program and, if requested, assists NNL owners and managers with the conservation of these important sites. Land acquisition by the federal government is not a goal of this program. National Natural Landmarks are nationally significant sites owned by a variety of land stewards, and their participation in this federal program

171-500: The case of volcanic craters) or melted ice . Its level rises until an equilibrium is reached between the rates of incoming and outgoing water. Sources of water loss singly or together may include evaporation , subsurface seepage, and, in places, surface leakage or overflow when the lake level reaches the lowest point on its rim. At such a saddle location, the upper portion of the lake is contained only by its adjacent natural volcanic dam ; continued leakage through or surface outflow across

190-545: The dam can erode its included material, thus lowering lake level until a new equilibrium of water flow, erosion, and rock resistance is established. If the volcanic dam portion erodes rapidly or fails catastrophically, the occurrence produces a breakout or outburst flood. With changes in environmental conditions over time, the occurrence of such floods is common to all natural dam types. These lakes may become soda lakes , many of which are associated with active tectonic and volcanic zones. A well-known crater lake, which bears

209-447: The designation. It is conceivable that state or local governments of their own volition could initiate regulations or zoning that might apply to an NNL. However, as of 2005 no examples of such a situation have been identified. Some states require planners to ascertain the location of NNLs. Listed by state or territory in alphabetical order. As of July 2024, there were 605 listings. Volcanic crater lake A volcanic crater lake

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228-647: The overall theme "Lakes and ponds" included large deep lakes, large shallow lakes, lakes of complex shape, crater lakes , kettle lake and potholes, oxbow lakes , dune lakes, sphagnum-bog lakes, lakes fed by thermal streams, tundra lakes and ponds, swamps and marshy areas , sinkhole lakes, unusually productive lakes, and lakes of high productivity and high clarity. The NNL program does not require designated properties to be owned by public entities. Lands under almost all forms of ownership or administration have been designated—federal, state, local, municipal, and private. Federal lands with NNLs include those administered by

247-569: The owner to preserve, as far as possible, the significant natural values of the site or area. Administration and preservation of National Natural Landmarks is solely the owner's responsibility. Either party may terminate the agreement after they notify the other. The NNL designation is made by the Secretary of the Interior after an in-depth scientific study of a potential site. All new designations must have owner concurrence. The selection process

266-532: The property nor induce any encumbrances on the property. NNL status does not transfer with changes in ownership. Participation in the NNL Program involves a voluntary commitment on the part of the landowner(s) to retain the integrity of their NNL property as it was when designated. If "major" habitat or landscape destruction is planned, participation in the NNL Program by a landowner would be disingenuous and meaningless. The federal action of designation imposes no new land use restrictions that were not in effect before

285-483: The remaining 18% are owned or administered by a mixture of public agencies and private owners. Participation in the NNL Program carries no requirements regarding public access. The NNL registry includes many sites of national significance that are open for public tours, but others are not. Since many NNLs are located on federal and state property, permission to visit is often unnecessary. Some private properties may be open to public visitation or just require permission from

304-466: The ridge. National Natural Landmark The National Natural Landmarks ( NNL ) Program recognizes and encourages the conservation of outstanding examples of the natural history of the United States . It is the only national natural areas program that identifies and recognizes the best examples of biological and geological features in both public and private ownership. The program

323-613: The same name as the geological feature, is Crater Lake in Oregon . It is located in the caldera of Mount Mazama . It is the deepest lake in the United States with a depth of 594 m (1,949 ft). Crater Lake is fed solely by falling rain and snow, with no inflow or outflow at the surface, and hence is one of the clearest lakes in the world. The highest volcano in the world, 6,893-m (22,615-ft) Ojos del Salado in Chile , has

342-420: The site manager. On the other hand, some NNL private landowners desire no visitors whatsoever and might even prosecute trespassers . The reasons for this viewpoint vary: potential property damage or liability , fragile or dangerous resources, and desire for solitude or no publicity. NNL designation is an agreement between the property owner and the federal government. NNL designation does not change ownership of

361-711: Was established on May 18, 1962, by United States Secretary of the Interior Stewart Udall . The program aims to encourage and support voluntary preservation of sites that illustrate the geological and ecological history of the United States. It also hopes to strengthen the public's appreciation of the country's natural heritage. As of July 2024, 605 sites have been added to the National Registry of Natural Landmarks. The registry includes nationally significant geological and ecological features in 48 states, American Samoa , Guam , Puerto Rico , and

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