North American Vertical Datum of 1988

The North American Vertical Datum of 1988 (NAVD 88) is the vertical datum for orthometric heights established for vertical control surveying in the United States of America based upon the General Adjustment of the North American Datum of 1988.

NAVD 88 was established in 1991 by the minimum-constraint adjustment of geodetic leveling observations in Canada, the United States, and Mexico. It held fixed the height of the primary tide gauge benchmark (surveying), referenced to the International Great Lakes Datum of 1985 local mean sea level (MSL) height value, at Rimouski, Quebec, Canada. Additional tidal bench mark elevations were not used due to the demonstrated variations in sea surface topography, i.e., that MSL is not the same equipotential surface at all tidal bench marks.

The definition of NAVD 88 uses the Helmert orthometric height, which calculates the location of the geoid (which approximates MSL) from modeled local gravity. The NAVD 88 model is based on then-available measurements, and remains fixed despite later improved geoid models.

NAVD 88 replaced the National Geodetic Vertical Datum of 1929 (NGVD 29), previously known as the Sea Level Datum of 1929. The elevation difference between points in a local area will show negligible change from one datum to the other, even though the elevation of both does change. NGVD 29 used a simple model of gravity based on latitude to calculate the geoid and did not take into account other variations. Thus, the elevation difference for points across the country does change between datums.

See also

External links

  • "United States Geological Survey home page".
  • "U.S. National Geodetic Survey home page".
  • "Geodetic Glossary". United States National Geodetic Survey.
  • "Orthometric Height Conversion tool". United States National Geodetic Survey.
Collegiate Peaks

The Collegiate Peaks (or Collegiate Range) is a name given to a section of the Sawatch Range of the Rocky Mountains located in central Colorado. Drainages to the east include headwaters of the Arkansas River.

The Collegiate Peaks include some of the highest mountains in the Rockies. The section is so named because several of the mountains are named for prominent universities.

Elevation

The elevation of a geographic location is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface (see Geodetic datum § Vertical datum).

The term elevation is mainly used when referring to points on the Earth's surface, while altitude or geopotential height is used for points above the surface, such as an aircraft in flight or a spacecraft in orbit, and depth is used for points below the surface.

Elevation is not to be confused with the distance from the center of the Earth. Due to the equatorial bulge, the summits of Mount Everest and Chimborazo have, respectively, the largest elevation and the largest geocentric distance.

Front Range

The Front Range is a mountain range of the Southern Rocky Mountains of North America located in the central portion of the U.S. State of Colorado, and southeastern portion of the U.S. State of Wyoming. It is the first mountain range encountered as one goes westbound along the 40th parallel north across the Great Plains of North America.

The Front Range runs north-south between Casper, Wyoming and Pueblo, Colorado and rises nearly 10,000 feet above the Great Plains. Longs Peak, Mount Evans, and Pikes Peak are its most prominent peaks, visible from the Interstate 25 corridor. The area is a popular destination for mountain biking, hiking, climbing, and camping during the warmer months and for skiing and snowboarding during winter. Millions of years ago, the present-day Front Range was home to ancient mountain ranges, deserts, beaches, and even oceans.The name "Front Range" is also applied to the Front Range Urban Corridor, the populated region of Colorado and Wyoming just east of the mountain range and extending from Cheyenne, Wyoming south to Pueblo, Colorado. This urban corridor benefits from the weather-moderating effect of the Front Range mountains, which help block prevailing storms.

Kaiser Point (Montana)

Kaiser Point (10,001 feet (3,048 m)) is located in the Lewis Range, Glacier National Park in the U.S. state of Montana. Maps indicate the peak is listed only by the elevation of 9,996 ft (3,047 m) according to the Sea Level Datum of 1929, however the updated elevation by the currently implemented North American Vertical Datum of 1988 indicates the peak exceeds 10,000 ft (3,048 m). The National Park Service reports that six peaks rise to over 10,000 ft (3,048 m) in Glacier National Park, but Kaiser Point is listed as the seventh tallest. Kaiser Point is only .67 miles (1.08 km) northeast of Mount Cleveland, the tallest summit in the park.

List of U.S. states and territories by elevation

The elevation of the U.S. states, the federal district, and the territories may be described in several ways. These include:

the elevation of their highest point;

the elevation of their lowest point

and the difference between (range of) their highest points and lowest points.The following list is a comparison of elevation absolutes in the United States. Data include interval measures of highest and lowest elevation for all 50 states, the District of Columbia, and territories.Which state or territory is "highest" and "lowest" is determined by the definition of "high" and "low". For instance, Alaska could be regarded as the highest state because Denali, at 20,310 feet (6,190.5 m), is the highest point in the United States. However, Colorado, with the highest mean elevation of any state as well as the highest low point, could also be considered a candidate for "highest state". Determining which state is "lowest" is equally problematic. California contains the Badwater Basin in Death Valley, at 279 feet (85 m) below sea level, the lowest point in the United States; while Florida has the lowest high point, and Delaware has the lowest mean elevation. Florida is also the flattest state, with the smallest difference between its highest and lowest points.

The list of highest points in each state is important to the sport of highpointing, where enthusiasts attempt to visit the highest point in each of the contiguous 48 states, or in all 50 states, or in all 50 states plus the District of Columbia and the territories. As of 2006, 155 people had reached the fifty state highpoints. Roughly 200–300 people attend the Highpointers Club convention each year.All elevations in the table below have been adjusted to the North American Vertical Datum of 1988. The mean elevation for each state, the District of Columbia and Puerto Rico is accurate to the nearest 100 ft (30 m). Mean elevation data is unavailable for the other U.S. territories.

List of highest points in California by county

This is a list of highest points in California, in alphabetical order by county.

All elevations use the North American Vertical Datum of 1988 (NAVD88), the currently accepted vertical control datum for United States, Canada and Mexico. Elevations are from the National Geodetic Survey (NGS) when available. Others are from the United States Geological Survey topographic maps when available. These can be found on the Peakbagger.com web pages. Elevations followed by a plus sign (+) were interpolated by the compiler using topographic map contour lines. The true elevation is between that shown and the elevation plus the contour line interval which is forty feet in most instances. Elevations from the NGS are rounded to the nearest whole number.

List of highest points in Nevada by county

This is a list of highest points in the U.S. state of Nevada, in alphabetical order by county.

All elevations use the North American Vertical Datum of 1988 (NAVD88), the currently accepted vertical control datum for United States, Canada and Mexico. Elevations are from the National Geodetic Survey when available. Others are from the United States Geological Survey topographic maps when available. Elevations followed by a plus sign (+) were interpolated using topographic map contour lines. The true elevation is between that shown and the elevation plus forty feet since the relevant topographic maps all use 40-foot contours.

Boundary Peak is the highest peak in terms of elevation, however, it has only 253 feet of clean prominence and so is usually considered a subsidiary peak of Montgomery Peak in California. Wheeler Peak, the next highest, has a clean prominence of 7,563 feet.

List of highest points in Oregon by county

This is a list of highest points in each county in the U.S. state of Oregon, in alphabetical order by county.

All elevations use the North American Vertical Datum of 1988 (NAVD88), the currently accepted vertical control datum for United States, Canada and Mexico. Elevations are from the National Geodetic Survey (NGS) when available. Others are from the United States Geological Survey topographic maps when available. These can be found on the Peakbagger.com web pages. Elevations from the NGS are rounded to the nearest whole number.

List of mountain ranges of Colorado

The following table lists the major mountain ranges of the U.S. State of Colorado. All of these ranges can be considered subranges of the Rocky Mountains.

As given in the table, topographic elevation is the vertical distance above the reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface. The topographic prominence of a summit is the elevation difference between that summit and the highest or key col to a higher summit. The topographic isolation of a summit is the minimum great-circle distance to a point of equal elevation.

All elevations in this article include an elevation adjustment from the National Geodetic Vertical Datum of 1929 (NGVD 29) to the North American Vertical Datum of 1988 (NAVD 88). For further information, please see this United States National Geodetic Survey note. If an elevation or prominence is calculated as a range of values, the arithmetic mean is shown.

List of the major 3000-meter summits of California

The following sortable table describes the 46 mountain peaks of the U.S. state of California with at least 3000 meters (9843 feet) of topographic elevation and at least 500 meters (1640 feet) of topographic prominence.

Topographic elevation is the vertical distance above the reference geoid, a mathematical model of Earth's sea level as an equipotential gravitational surface. The topographic prominence of a summit is the elevation difference between that summit and the highest or key col to a higher summit. The topographic isolation of a summit is the minimum great-circle distance to a point of equal elevation.

This article defines a significant summit as a summit with at least 100 meters (328.1 feet) of topographic prominence, and a major summit as a summit with at least 500 meters (1640 feet) of topographic prominence. An ultra-prominent summit is a summit with at least 1500 meters (4921 feet) of topographic prominence. There are 126 ultra-prominent summits in the United States.

All elevations include an adjustment from the National Geodetic Vertical Datum of 1929 (NGVD 29) to the North American Vertical Datum of 1988 (NAVD 88). For further information, please see this United States National Geodetic Survey note.

If an elevation or prominence is calculated as a range of values, the arithmetic mean is shown.

List of the major 4000-meter summits of California

The following sortable table comprises the 16 mountain peaks of the U.S. State of California with at least 4000 meters (13,123 feet) of topographic elevation and at least 500 meters (1640 feet) of topographic prominence.

Topographic elevation is the vertical distance above the reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface. The topographic prominence of a summit is the elevation difference between that summit and the highest or key col to a higher summit. The topographic isolation of a summit is the minimum great-circle distance to a point of equal elevation.

This article defines a significant summit as a summit with at least 100 meters (328.1 feet) of topographic prominence, and a major summit as a summit with at least 500 meters (1640 feet) of topographic prominence. An ultra-prominent summit is a summit with at least 1500 meters (4921 feet) of topographic prominence. There are 126 ultra-prominent summits in the United States.

All elevations include an adjustment from the National Geodetic Vertical Datum of 1929 (NGVD 29) to the North American Vertical Datum of 1988 (NAVD 88). For further information, please see this United States National Geodetic Survey note.

If an elevation or prominence is calculated as a range of values, the arithmetic mean is shown.

List of the most prominent summits of Colorado

The following sortable table comprises the 100 most topographically prominent mountain peaks of the U.S. State of Colorado.

Topographic elevation is the vertical distance above the reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface. The topographic prominence of a summit is the elevation difference between that summit and the highest or key col to a higher summit. The topographic isolation of a summit is the minimum great-circle distance to a point of equal elevation.

This article defines a significant summit as a summit with at least 100 meters (328.1 feet) of topographic prominence, and a major summit as a summit with at least 500 meters (1640 feet) of topographic prominence. An ultra-prominent summit is a summit with at least 1500 meters (4921 feet) of topographic prominence. There are 126 ultra-prominent summits in the United States.

All elevations include an adjustment from the National Geodetic Vertical Datum of 1929 (NGVD 29) to the North American Vertical Datum of 1988 (NAVD 88). For further information, please see this United States National Geodetic Survey note.

If an elevation or prominence is calculated as a range of values, the arithmetic mean is shown.

Mount Elbert

Mount Elbert is the highest summit of the Rocky Mountains of North America and the highest point in the U.S. state of Colorado and the entire Mississippi River drainage basin. The ultra-prominent 14,440-foot (4401.2 m) fourteener is the highest peak in the Sawatch Range and the second-highest summit in the contiguous United States after Mount Whitney. Mount Elbert is located in San Isabel National Forest, 12.1 miles (19.4 km) southwest (bearing 223°) of the City of Leadville in Lake County, Colorado.The mountain was named in honor of a Colorado statesman, Samuel Hitt Elbert, who was active in the formative period of the state and Governor of the Territory of Colorado from 1873 to 1874. Henry W. Stuckle of the Hayden Survey was the first to record an ascent of the peak, in 1874. The easiest and most popular climbing routes are categorized as Class 1 to 2 or A+ in mountaineering parlance. Mount Elbert is therefore often referred to as the "gentle giant" that tops all others in the Rocky Mountains.

North American Datum

The North American Datum (NAD) is the datum now used to define the geodetic network in North America. A datum is a formal description of the shape of the Earth along with an "anchor" point for the coordinate system. In surveying, cartography, and land-use planning, two North American Datums are in use: the North American Datum of 1927 (NAD 27) and the North American Datum of 1983 (NAD 83). Both are geodetic reference systems based on slightly different assumptions and measurements.

Sabine Pass

Sabine Pass is the natural outlet of Sabine Lake into the Gulf of Mexico. It borders Jefferson County, Texas, and Cameron Parish, Louisiana.

San Juan Mountains

The San Juan Mountains are a high and rugged mountain range in the Rocky Mountains in southwestern Colorado and northwestern New Mexico. The area is highly mineralized (the Colorado Mineral Belt) and figured in the gold and silver mining industry of early Colorado. Major towns, all old mining camps, include Creede, Lake City, Silverton, Ouray, and Telluride. Large scale mining has ended in the region, although independent prospectors still work claims throughout the range. The last large scale mines were the Sunnyside Mine near Silverton, which operated until late in the 20th century and the Idarado Mine on Red Mountain Pass that closed down in the 1970s. Famous old San Juan mines include the Camp Bird and Smuggler Union mines, both located between Telluride and Ouray.

The Summitville mine was the scene of a major environmental disaster in the 1990s when the liner of a cyanide-laced tailing pond began leaking heavily. Summitville is in the Summitville caldera, one of many extinct volcanoes making up the San Juan volcanic field. One, La Garita Caldera, is 35 miles (56 km) in diameter. Large beds of lava, some extending under the floor of the San Luis Valley, are characteristic of the eastern slope of the San Juans.

Tourism is now a major part of the regional economy, with the narrow gauge railway between Durango and Silverton being an attraction in the summer. Jeeping is popular on the old trails which linked the historic mining camps, including the notorious Black Bear Road. Visiting old ghost towns is popular, as is wilderness trekking and mountain climbing. Many of the old mining camps are now popular sites of summer homes. Though the San Juans are extremely steep and receive a lot of snow, so far only Telluride has made the transition to a major ski resort. Purgatory Resort, once known as Durango Mountain Resort, is a small ski area 26 miles north of Durango. There is also skiing on Wolf Creek Pass at the Wolf Creek ski area. Recently Silverton Mountain ski area has begun operation near Silverton.

The Rio Grande drains the east side of the range. The other side of the San Juans, the western slope of the continental divide, is drained by tributaries of the San Juan, Dolores and Gunnison rivers, which all flow into the Colorado River.

The San Juan and Uncompahgre National Forests cover a large portion of the San Juan Mountains.

The San Juan Mountains are also distinctive for their high altitude plateaus and peaks. As a result, facilities in the towns and cities of the region are among the highest in the nation. Telluride Airport, at an elevation of 9,070 feet, is the highest in the United States with regularly scheduled commercial service.

Sea Level Datum of 1929

The Sea Level Datum of 1929 was the vertical datum established for vertical control surveying in the United States of America by the General Adjustment of 1929. The datum was used to measure the elevation of a point above and depression below mean sea level (MSL).

Mean sea level was measured at 26 tide gauges: 21 in the United States and 5 in Canada. The datum was defined by the observed heights of mean sea level at the 26 tide gauges and by the set of elevations of all bench marks resulting from the adjustment of observations. The adjustment required a total of 66,315 miles (106,724 km) of levelling with 246 closed circuits and 25 circuits at sea level.

Since the Sea Level Datum of 1929 was a hybrid model, it was not a pure model of mean sea level, the geoid, or any other equipotential surface. Therefore, it was renamed the National Geodetic Vertical Datum of 1929 (NGVD 29) in 1973. NGVD29 was superseded by the North American Vertical Datum of 1988 (NAVD 88), based upon an equipotential definition and a readjustment, although many cities and U.S. Army Corps of Engineers projects with established data continued to use the older datum.

VERTCON

VERTCON is a computer program that computes the modeled difference in orthometric height between the North American Vertical Datum of 1988 (NAVD 88) and the National Geodetic Vertical Datum of 1929 (NGVD 29) for a location in the contiguous United States. The parameters required are the latitude and longitude of the location.

The program was created by the National Geodetic Survey (NGS) in 1994 and is available as an online tool, or PC executable package. The package contains the Perl source code. The NGS is the government agency charged with responsibility for the National Spatial Reference System.

West Elk Mountains

The West Elk Mountains are a high mountain range in the west-central part of the U.S. state of Colorado. They lie primarily within the Gunnison National Forest, and part of the range is protected as the West Elk Wilderness. The range is primarily located in Gunnison County, with small parts in eastern Delta and Montrose counties.

The West Elks are surrounded by tributaries of the Gunnison River. The range is bounded on the north by the North Fork of the Gunnison and on the east by the East River, another tributary of the Gunnison. On the south and west it is contiguous with Black Mesa and Fruitland Mesa, both part of the uplift in which sits the Black Canyon of the Gunnison. On the northeast it is contiguous with the Elk Mountains, being separated from them by Anthracite Creek and Coal Creek. Nearby towns include Gunnison, Paonia, and the ski resort of Crested Butte.

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