SOME FREQUENTLY MISQUOTED ELEVATIONS


This page lists summit elevations and other topographic claims, which, in my opinion, many authorities get wrong.


  • Latin America
  • Asia
  • Africa and Middle East
  • Australasia
  • Europe NEW Updated 25 November 2010 with new information from Georgian HP Shkhara.
  • United States
  • United Kingdom

  • Viewfinder Panoramas Home Page

    Glossary: SRTM; GPS; HP=High Point. Numbers in square brackets refer to acknowledgements. Readers with knowledge of anything that should be added to this page: you are welcome to contact me at viewfinder--at--ferrantizsolzcozuk. I hate spam so you will need to replace the --at-- with the symbol and the z's with dots.

    Summit Elevations: Spot heights and Google Earth. It is occasionally asked why elevation maxima at mountain summits on Google Earth fall below published and GPS spot heights. The terrain data used by Google Earth to generate three dimensional images are, for most of the world, derived from digital elevation models, in turn derived primarily from SRTM data. These data typically have a three arc second resolution, i.e. they provide elevation values at three second (approximately 90 metres at the equator) intervals. Each given 3 second value is averaged over a 3 second x 3 second area. If a mountain summit falls within such an area, the given elevation for that area will necessarily be lower than the elevation at the summit. The difference depends on the local relief; the steeper the summit, the greater the difference. Differences in the order of 15 metres are fairly normal, and differences of more than 50 metres can, and do, occur. It is also worth mentioning that that GPS devices measure ellipsoid heights, which must be converted to the geoid using data stored within the GPS device itself. The quality of these data are, for some parts of the world, such that GPS readings of up to +/- 10 metres may occur along a sea shore, with corresponding errors at higher elevations. It is further worth noting that, in some places, especially in areas of high relief, SRTM data are incomplete, and in the absence of any other data, Google have filled the gaps using interpolation. Consequent differences between Google summit heights and actual summit heights can run into hundreds of metres, especially in some tropical areas where no alternative data sources are available.


    Why these elevations should be corrected. The Internet has become an important medium for the free flow of knowledge, to the general benefit. But where that information is wrong or inaccurate, that benefit is compromised. And there are practical reasons why high point inaccuracies compromise that benefit.

    Many climbers today carry GPS devices. If I were climbing in the High Andes and my GPS showed 6500 metres, but I were starting to work harder to breathe in the rarified atmosphere, I would surely want to know if I were 300m or 400m below the summit. And if the mist were down, I may then need my GPS device to be sure that I had reached the summit. For that I would need an accurate mountain elevation to compare with my GPS reading.

    The day is surely approaching when all aircraft, including light aircraft, will be equipped with computers carrying digital elevation/obstacle data and GPS receivers connected to a siren. These will provide cheap and reliable safety technology in mountain mist. But if the elevation data is not accurate then the value of this technology will be reduced.

    More generally, I cannot resist my urge to express my contempt for politically and commercially motivated elevation inflation. Where elevations are outside the error margin of the most accurate available elevations, official and august authorities should correct them in the manner that has been done by those of Brazil and Venezuela, and commercial organisations should not continue to dishonestly bill the inflated elevations.

    I have a further argument. Recently products like Google Earth and NASA World Wind have been made freely available. The fly-by effects are amazing, but for mountainous areas their quality is compromised by poor quality digital elevation data. It is time to sweep away the fiction and put together a complete and accurate worldwide digital elevation model. I am working on this, see here.

    It could be argued that inflated elevations contribute positively to safety. I strongly disagree. To give an analogy: I once set my watch ten minutes fast in the hope that it would make me more punctual. But soon I got used to this deliberate error margin and the ultimate effect on my timekeeping was negative.

    So to all webmasters of sites that include high point data I say, please check the summits that follow, and if you find my evidence convincing, please update your information!


    Do not take august sources as gospel. Maps published by the national surveys of developed (delete Argentina but add Nepal) countries tend to be reliable. Elsewhere, other than within its no-data areas, the most accurate general elevation information is obtainable from NASA's SRTM. The next best is Russian military topographic mapping, which agrees much more closely with SRTM than its American military equivalent (ONC,TPC,JOG,DMA etc). Locally, excellent information comes from internet reports by independent field researchers, professional or otherwise, with good knowledge of GPS. These researchers tend to be keen to establish reputations, and consequently take care to be accurate. August but less reliable sources include the CIA, the Times Atlas, Guinness World Records, MSN Encarta, the National Geographic Society, and factbooks published by large corporations. These authorities have become bureaucracies who take less trouble to keep their information up to date. The well known peakware site has recently been given a facelift but much needed effort to improve its accuracy is not evident. Wikipedia, whose authors and contributors, in accordance with its reliability paragraph, tend to copy these august sources, should not be completely trusted either, but it does allow and gets considerable user input and strenuous efforts are being made by some of its contributors to improve it.



    LATIN AMERICA


  • The High Andes
  • Paine Cordillera, Southern Chile
  • Mexican Volcanoes
  • Pico Duarte, HP Caribbean
  • Pico da Neblina, HP Brazil
  • Pico Bolivar, Venezuela
  • Chimborazo, Ecuador
  • Mogoton, Nicaragua


    The High Andes
  • Ojos del Salado, 2nd HP Andes
  • True elevation: 6893m ± 15m
  • Elevation on some official maps: 6864m

  • Monte Pissis, 3rd HP Andes
  • True elevation: 6793m (precise DGPS surveys)
  • Elevation on some official maps: 6882m

    I do not know whether or not the elevations that imply that Monte Pissis is higher are still officially believed, but they were for some time and still appear on some maps. For more details see the mountain's references section on Wikipedia. An often quoted elevation of 6872m for nearby Bonete Chico is also inflated; its true elevation is in the mid 6700s. Cerro Mercedario is officially quoted at 6770m but SRTM data suggests it is about 6720m and an (albeit vague) GPS report is consistent with this.

    As far as I am aware the elevations on John Biggar's list of 6000m Andes summits here are accurate, and the elevations given in the 2005 edition of his book "The Andes: A Guide for Climbers" are as accurate as the current state of knowledge (2005) permits.


    Paine Cordillera, Southern Chile

    Despite being relatively accessible, widely photographed, and increasingly popular, this group remains one of the world's worst surveyed. Inconsistencies abound. Cerro Paine Grande's Cumbre Principal is universally quoted at 3050m but it is interesting that when converted to feet this elevation tops 10,000. It seems that, once upon a time, it was in someone's interest to bill this as a 3000m/10000ft summit, and this elevation has not up to now been challenged or investigated. Calculations from geometric analysis of some photographs suggest that its true elevation is about 2600m, although more recent analysis of narrower angle and higher resolution/quality photography (see 1) suggested that it is nearer to 2800m. This was confirmed in August 2011 when an expedition reported it to be 2884m (see 2). There are definitely major errors in several of the elevations of other summits that appear on most maps. Please, please could someone go and survey this range properly!

    Other Patagonian summits. The HP of Chilean Patagonia, San Valentin, is officially deflated to 3911m on the Chilean map but SRTM shows that its true height exceeds 4000m, and this is supported by a GPS survey by a Chilean expedition. Another highly prominent summit, belonging to Volcan Lautaro, is officially under 3400m but the SRTM cells rise to a maximum of 3560m. The lesser known but still prominent volcano Cerro Maca, at latitude 45S, has been quoted at over 3000m but SRTM suggests it is about 2300m.


    Mexican Volcanoes
    Pico de Orizaba (Citlatapetl), HP Mexico.
  • Most likely elevation: 5636m
  • Elevations given by many sources: 5700m+

    The official elevation is 5611m but this is from an old survey, and elevations over 5700m are widely quoted. An elevation of 5636m, based on a survey by a GPS expert (see page 23), would seem to me to be the most likely to be the most accurate. Sources in error include the 5747m elevation reported on this page by the National Geographic Society's research department.

    Ixtaccihuatl and Popocatepetl. The most frequently quoted elevation for nearby Iztaccihuatl is 5286m but SRTM (top 3" cell 5216m) and the official Mexican survey INEGI (see below) agree that the actual elevation is about 5220-5230m. A frequently used elevation of 5452m for Popocatepetl is probably also too high; SRTM and INEGI suggest 5410m may be accurate, but this is less clear cut. See the following files:

  • Ixta INEGI 50K DRG. Unfortunately this is ambiguous. There may be two summit 5200m ring contours, defining a crater ring, or the innermost may be a 5220m contour that has been incorrectly emboldened. But the 5300m index contour that seems to be implicit at first sight can be ruled out by analysing this summitpost image and other images. Details of this analysis can be found here.
  • Ixta 3" SRTM DEM
  • Popo INEGI 50K DRG
  • Popo 3" SRTM DEM
  • Orizaba 3" SRTM DEM (of limited value bacause of crater voids)


    Pico Duarte, HP Caribbean
  • True elevation: 3098m
  • Elevation on most websites: 3175m

    For details of the 3098m measurement see the Caribbean Journal of Science. The reading is consistent with both SRTM data and a GPS measurement obtained in Jaunary 2005 by topographic research colleagues Adam Helman, Edward Earl and Bob Packard.


    Pico da Neblina, HP Brazil
  • Official and true elevation: 2994m
  • Elevation given by most authorities: 3014m

    This is not a 3000m+ summit. Click here for more information.


    Pico Bolivar, Venezuela
  • Official and true elevation: 4980m
  • Elevation given by most authorities: 5007m

    This is not a 5000m+ summit. Click here for more information (in Spanish). [2]


    Chimborazo, Ecuador
  • Most likely elevation: 6267m
  • Elevation often quoted: 6310m

    The 6267m elevation was measured by a British soldier called Mike Jenkins by DGPS in 1993, and I do not think it is officially disputed by Ecuador, but an older elevation of 6310m is still often seen in print and on some websites.


    Cerro Mogoton, HP Nicaragua
  • Elevation: 2438m according to CIA, 2106m according to local 1:50000 topographic mapping. SRTM data, whose highest 3" cell in the area is 2094m, firmly upholds and is consistent with the lower elevation, exposes an error of more than 300 metres in the CIA data and is evidence that the CIA source should not be considered reliable.


    HIGH ASIA


    In general, elevation inflation does not occur in High Asia. In particular, the excellent Finnmaps of Nepal re-affirm the traditional elevations. Despite lack of local access, the Survey of India was able to measure the majority of Himalayan summits with remarkable precision as early as the mid-19th century. An unfortunate blip occurred about 20 years ago when someone suggested, on evidence that he conceded was weak, that K2 may be higher than Everest. Unfortunately sensation seeking journalists, no doubt with their minds tuned in to sales at the expense of fact, reported this as if it were proven. Infact, without exception, significant elevation errors for major summits in High Asia occur in areas outside the scope of the Survey of India. Some of China's most prominent mountains are covered by an excellent series of 14 "snow mountain" maps, but elsewhere, unfortunately, where inflated elevations have become established, some authorities seem to be unwilling to revise them.

    For a long time, much of the Tibet plateau was thought to be about 700 metres higher than it is. Its general elevation has been fairly well known since the 1980's. but, twenty years later, many publications and websites are still quoting summit elevations based on older Tibet plateau elevation assumptions. Ulugh Muztagh is one of many examples of this.

    As far as I checked it, the Highest Mountains list here looks to be the most complete and accurate that is currently available. Refinements to this list are ongoing.

  • Khardung La Road Pass
  • Ulugh Muztagh, North Tibet
  • Zangser Kangri, North Tibet
  • Chomo Lhari, Tibet/Bhutan
  • Kula Kangri and Kangkar Punsum, Tibet and Tibet/Bhutan
  • Kongur Shan, West China
  • Hispar Muztagh, Karakoram (several summits)
  • Singhi Kangri, Karakoram
  • Mount Kailash, Tibet (aka Kangrinboqe)
  • Khan Tengri, Tien Shan
  • Keokradong, false HP, Bangladesh
  • Everest and K2
  • South East Asia


    Khardung La Road Pass, NE of Leh, Indian Himalaya
  • Location: N 34°16'44" E 77°36'17"
  • True elevation: 5359m
  • Elevation claimed by Indian border roads association: 18380 feet (5602m)
  • Authority even more in error: Guinness World Records.

    Sources in agreement: SRTM, GPS and the Soviet 200k topo of the area. And contrary to the claim made by the Indian and many other authorities, there are higher motorable roads in Tibet. For more details, including a list of GPS observations, click here.[5]

    It is claimed by some authorities that Marsimik La, India, is 18,634 feet, but this is equivalent to 5,680 metres, and the summit sign that markes the claim also states 5,590 metres. SRTM data suggests that its elevation is 5,582 metres; and 2006 GPS reading of 5,598 metres had been reported to me. So the 18,634 feet claim seems to be inflated, but Marsimik is still a possible "highest motorable pass" candidate. For more information about high passes, see my high passes page.


    Ulugh Muztagh, North Tibetan Plateau
  • True elevation: 6973m
  • Elevation still quoted by some august authorities: 7723m

    Also known as Muztag Feng. The true elevation was established by a Sino-American expedition in 1985 and confirmed by the official Guide to Mountaineering in China, detailed Chinese mapping, and by SRTM. The 2005 Penguin Book of Facts is among those that still give an elevation of more than 7700m. So do Encyclopedia Britannica and the Times Atlas of the World, which gives an equally crazy elevation for a similar mountain called Buka Daban about 250km further east. See above. For more information, see summitpost.


    Zangser Kangri, North Tibetan Plateau
  • Elevation given in this UK Alpine Club database: 6950m
  • True elevation: About 400m lower

    Sources in agreement about this: SRTM, GPS, the Soviet 200k topo of the area, the (official) Guide to Mountaineering in China, and summitpost. SRTM suggests the elevation is most likely to be about 6530m; the other sources are all within 100m of this.


    Chomo Lhari, Tibet/Bhutan border
  • Official elevation: 7326m

    Update 11.09.2011: contrary to the suggestion posted here earlier, I now believe the official elevation and that there has been no elevation inflation. The summit was measured in 1858 at 7298 metres and revised to 7326 metres on modern Chinese mapping.


    Kula Kangri and Kangkar Punsum, Tibet and Tibet/Bhutan
  • Respective locations: N 28°14' E 90°37' and N 28°03' E 90°27'
  • Respective elevations according to traditional sources: 7554m and 7541m
  • Respective elevations according to modern Chinese survey, reported by a Japanese source: 7538m and 7570m

    The differences are small, but they raise interesting questions about which is higher and the HP of Bhutan. These are discussed here. This page and its associated color relief map, showing the topographical divide, support the new elevations and argue that, despite the view of most authorities, Kula Kangri is wholly in Tibet and therefore NOT the HP of Bhutan, whatever its height with respect to KP [1].


    Kongur Shan, West China
  • Likely elevation: 7649m
  • Elevation given by most authorities: 7719m

    The Guide to Mountaineering in China gives 7649m. Confusingly, the authoritive Chinese Snow Map gives both 7719m and 7649m on different sections of the map. Both sources give the elevation of the northeast dome as 7625m. In "Kongur: China's elusive Summit" Chris Bonington writes that seen from the NE dome "(the main summit) is undoubtedly the highest point on Kongur, though probably by not more than thirty metres or so". Despite clear weather and lack of time, Bonington's party climbed both summits because, on reaching the main summit, they found that they could not be sure that the NE summit was lower. The two summits are ±700m apart; had there been a 94m height difference they would surely have seen clearly that the NE summit was lower. Therefore I concluded that the 7649m elevation is more accurate. I have subsequenly been informed of GPS readings of 7669m by Russian and Italian mountaineers, but reliable details of this are lacking. [1]


    Hispar Muztagh, Karakoram
    These high summits lie west of Disteghil Sar. Customary elevations for Trivor, Momhil Sar and Balurong Sar, west of Disteghil Sar, are 7728m, 7334m and 7200m but geometric analysis of a high level photograph showing Trivor (left) and Momhil Sar (right) from Balurong Sar shows that these elevations cannot all be right, but that the elevations given by Russian topographic mapping may all be right. These elevations are: Trivor 7577m, Momhil Sar 7414m, Balurong Sar 7134m [10].

    The Yazghil Domes are quoted in the 7300's by all maps that I have seen, but some authorities go up to 7559m. Higher quotes are usually attributed to the main dome but not the north dome. A high level photograph in the Japanese Karakoram study shows such an implicit difference in height between the two domes to be just so much hogwash. There is also enough local SRTM data on around these summits to trash any summit claim over 7400m. 7559m is 24800 feet and could be the creature of the accidental or convenient juggling of 8's and 0's [10].

    Most authorities agree that Singhi Kangri, in the Siachen Muztagh, eastern Karakoram, is 7207m, but there is a bad case of misinformation here [10].


    Kangrinboqe (Holy Mount Kailash), Tibet
  • Most authoritive elevation: 6638m
  • Elevation on most websites: 6728m

    This is the mountain that is well known to pilgrims of many faiths as "Holy Mount Kailash". Internet sites and a well known august authority give it more than 6700m but I prefer not to be in awe of these and to go with the Guide to Mountaineering in China and its Chinese Snow Mountain map, which agree on 6638m. Similarly, internet sites give relatively nearby Naimonanyi (aka Gurla Mandhata) 7728m but the above Chinese authorities agree on 7694m.


    Khan Tengri, Tien Shan
    Elevations of 6995m and 7010m metres are both often quoted. It seems clear that there is a survey flag whose elevation is 6995m, and that this represents the mountain's highest rockhead point. This is referenced (in German) here.

    The relevant sentences from the above link translate into English as follows: It only just scrapes the magic 7000 metre limit because of its white ice and snowcap. But that does not count. The rock peak is just 5 metres short of this, otherwise it would be the most northerly seven thousander (peak) in the world.

    Readers can decide for themselves whether the ice and snow cap should count towards the 7000m mark, or whether authorities should demote Mont Blanc to under 4800m and the South Pole to somewhere around sea level. The existence of a 7000m+ ice and snow cap is substantiated by a trip report by Peter Csizmadia here (in Hungarian). The exact height of this probably varies with snow conditions. The higher elevation means that this summit qualifies for the 7000m "snow leopard" list.


    Keokradong, false HP, Bangladesh
  • True elevation: 883m
  • Elevation According to the CIA and other websites who copy this incompetent source: 1230m

    Compatible sources: Russian 200K map and SRTM. The highest 3" SRTM cell in Bangladesh that I can find is 1049m at N 21°47'12" E 92°36'36", where the Russian 200K map gives a spot height of 1052m in the Mowdok range, on or close to the borders with Myanmar and India. More recent claims by the Bangladeshi authorities that nearby Tazing Dong is their national high point are equally incompatible with reliable GPS(supplied by Ginge Fullen)/SRTM/Russian sources.[8]


    Everest and K2
    The customary elevations for these are 8848m and 8611m respectively. Apart from the temporary incident mentioned above, no significant variations have been reported. Minor variations (up to five metres) are reported from time to time, but there seems to be no consistency in these. They are probably more about publicity than hard evidence and in my opinion they should be ignored until a more consistent pattern among more independent measurements can be shown.


    South East Asia
    Discrepancies between SRTM and official elevations are quite common in South East Asia. Hilonghilong, on Mindanao, Philippines, cited as 2012m but nearer to 1920m according to SRTM, is an example. Persistent cloud cover may obstruct ground surveys.[6]


    AFRICA AND MIDDLE EAST


  • Ras Dejen, HP Ethiopia
  • Mont Iboundji, false HP, Gabon
  • Tsodilo Hills, false HP, Botswana
  • Damavand, Iran
  • Jabal an Nabi Shu'ayb, HP Yemen
  • Jabal Sawda', HP(?), Saudi Arabia
  • Mount Cameroon
  • Mount Wuteve, Liberia


    Ras Dejen, HP Ethiopia
  • Most likely elevation: 4533-4550m
  • Elevation on most websites: 4620m
  • Often incorrectly called Ras Dashan or Ras Dashen

    4620m, which is based on an Italian military survey dating back to the 1930's, is way above anything compatible with SRTM. Over to Prof. Hans Hurni of the University of Bern institute of Geography: "This project did a full cover survey with air photography (about 1:40,000), triangulation and stereoscopic mapping of the whole country in the late 1960s early 1970s. To my knowledge, the elevation names are rather accurate (to the meter), and Ras Dejen (not to be spelt Ras Dashan), the highest peak of Ethiopia, is given the altitude of 4533 m asl, based on a polygon they started from the Red Sea"[6]. 4533m is consistent with SRTM data, but in 2007 a DGPS survey by a French-Italian team found the slightly higher elevation of 4550 metres, which is within the likely SRTM error margin.


    Mont Iboundji, false HP, Gabon
  • True elevation: c.1000m
  • Elevation According to the CIA and other websites who copy this incompetent source: 1575m

    The highest 3" SRTM cell in Gabon appears to be on Mont Bengoué, 1070m at 00°57'21"N, 13°41'09"E. The CIA also give a wrong 903m high point for neighbouring Congo, whose true HP is Mont Nabeba, 1020m at 1°50'39" N 13°59'27" E [8] [11].


    Tsodilo Hills, false HP, Botswana
  • True elevation: no more than 1400m
  • Elevation According to the CIA and other websites who copy this incompetent source, and also wrongly claim this as Botswana's highest point: 1489m

    The highest 3" SRTM cell in Botswana appears to be on Monalanong Hill, in the SE of the country, 1494m at 24°50'27"N, 25°39'54"E, but there are other nearby competing high points, Otse and Kanye, that are within the SRTM error margin. Analysis of local SRTM cells suggests that a GPS reading of 1496m obtained by Ginge Fullen on Otse is accurate. [8][11]


    Damavand, HP Iran
  • Most likely elevation: 5610m
  • Elevation on most websites: 5671m

    The lower height, which, unlike the higher and more commonly quoted height, is consistent with SRTM data, was official at the Statistical Centre of Iran. Unfortunately this link is now dead. Damavand was measured in 2007 by Norwegian climber Petter Bjørstad using hand held GPS. His results can be found here (see "Day 2, August 14, summit day"). He writes:

    Straight across the crater, there was another point along the rim that looked equally high. We decided to take a walk around the entire crater, visit this opposite point and measure it carefully. The highest rock on the first (and likely official) summit had measured 5622 meter after a long period of sampling. The point across is located at N35:57.318, E052:06.553, and after 300 samples, the best average value read 5623 meter. From this viewpoint, we had a good view back across the crater, from left to the first high point, then further right along the rim towards the point where we were sitting. This difference is too small to decide, however, it is clear (see also the pictures) that these two points along the crater rim are indeed very similar in height. Again, with the assumption that the GPS is (consistently, see below) about 10 meter too high, this strongly supports an official height of Damavand at 5610 meter. In any event, all references to an elevation of 5671 meter should be changed, this is absolutely wrong.

    The Caspian Sea was warm, about 30 Centigrade, its salinity is about 1.2 percent, so about one third of the normal oceans. I measured the elevation very carefully in order to calibrate my GPS and after several hundred sample readings it read elevation minus 17 meter, location N36:36.919, E052:11.021. Not too surprisingly, this is 11 meter too high, fairly consistent with observations in the Mediterranean, in Indonesia and in Taiwan. It is therefore likely that the summit observations should be adjusted down by approximately 10 meter.

    Here are some of the sources that have been used in support of the higher elevation: CIA, which is exposed elsewhere on this page as being very unreliable; NASA, whose 2005 article probably copied the CIA, and USGS, which in support of 5670 metres provides nothing more than a 1937 estimate by a geologist. Claims that 5670 is based on laser measurement by NASA or any other advanced technology are without foundation. SRTM 3" data shows nothing over 5600, which for a summit like Damavand is not consistent with 5670.

    A page written by a local guide upholds 5671, but cites GPS readings of 5630 and 5645 with an error margin of +/- 15, which contradict 5671. The 5645 is out of line with other GPS readings, which are all in the 5620-5630 range, and was probably taken in pressure mode, which is less accurate than satellite mode. These GPS readings are also consistent with a map based on official Iranian 1:50,000 mapping, which shows 5628, but examination of the mapping's topographic layer suggests that its topography was captured with US technical support in pre-revolutionary times. I am informed that new official hi-tech measurements have been carried out. The results are still to be made public. I still hold with Petter's Caspian Sea calibration analysis, which he has demonstrated from other parts of the world too. Hand held GPS readings are sometimes consistently in error because they all seem to use the same imperfect ellipsoid-geoid conversion model. But it may be proved that 5610m is too low and that the map and GPS readings are more accurate.

    Footnote: Petter's comment that references to 5671 should all be changed apply equally to 5670. The original 1937 estimate was 5670, I would guess that someone subsequently added 1 to make it look more like a modern, accurate measurement. 1 foot was similarly added to an old Everest survey when it happened to come to exactly 29,000.


    Jabal an Nabi Shu'ayb, HP Yemen
  • True elevation: 3666m
  • Official elevation: 3760m

    The highest local 3" SRTM cell is 3653m and the cells would seem to be incompatible with a high point exceeding 3700m. The elevation given here and here looks good to me.


    Jabal Sawda', HP(?), Saudi Arabia
  • True elevation: c.3000m
  • Official elevation: 3133m

    The highest local 3" SRTM cell is 2991m and the cells would seem to be incompatible with anything over 3020m. A 2991m cell belonging to Jaw-da, nearer the Yemen border, would seem to suggest that this is the true Saudi HP.


    Mount Cameroon
  • Likely elevation: c. 4050m
  • Official elevation: 4095m

    The highest local 3" SRTM cell is 4024m which suggests that the true elevation is probably not higher than 4070m, and may be no higher than 4040m.


    Mount Wuteve, HP Liberia
  • Likely elevation: 1380m according to CIA, 1447m according to LIB50 Sheet 2461-III 1:50000. SRTM data, whose highest 3" cell in the area is 1424m, firmly upholds and is consistent with the higher elevation.


    AUSTRALASIA


  • Mount Carstenz, Papua, HP Australasia.
  • Solomon Islands
  • Finisterre range, Papua New Guinea
  • Gunung Agung, HP Bali


    Mount Carstenz, Papua, HP Australasia
  • True elevation: 4884m
  • Elevation on most websites: 5030m

    The elevation of 4884m, which is consistent with IFSAR data, is provided by the "Seven Summits" pages, but elevations of more than 5000m are still given by several august authorities.


    Solomon Islands
  • True HP: Popomanaseu, elevation 2335m
  • HP on other websites: Makarakomburu, incorrect elevation 2447m

    Sources: SRTM, higher resolution IFSAR data, and official 50k mapping.


    Finisterre range, Papua New Guinea
  • Likely elevation: c.4120m
  • Official elevation: 4175m

    The official elevation would seem to be based on an old survey and, for some reason, the authorities have not cared to update it. The relative sizes of the 3800m and 4000m contour rings on the 1:250,000 map bring this elevation into question, and the highest 3" SRTM cell is 4102m, which suggests a lower elevation, about 4130m. The highest SRTM cell around Mount Sarawaket, about 60km south-east of the "Point 4175m", is 4094m so it is possible that this point, not "4175m", should be occupying the place among the World's Finest 50.


    Gunung Agung, HP Bali
  • True elevation: c.3031m
  • Elevation on most websites: 3142m

    Sources: IFSAR data, and the relevant peakbagger page which supplies altimeter evidence. The higher elevation may be from a survey pre-dating an eruption.


    EUROPE


    Shkhara, HP Georgia, Caucasus mountains.

  • True elevation (July 2010): 5193m
  • Elevations given by many authorities: 5068m, 5158m, 5201m

    The 5193m elevation was obtained by Austrian geographer Peter Schoen, and Boris Avdeev from the University of Michigan, with the support of GeoAT, in July 2010 and published in November 2010. The lower alternatives are those of spot heights that appear on Soviet era mapping. The highest point, which does not appear to have ever been accurately measured before, lies slightly further east along the main ridge. The 5201m elevation was a reasonable estimate of the true height based on previously available information. The 5193m elevation may be subject to seasonal variations in snow and ice cover; the rock head elevation is lower.

    Etna, Sicily.

  • True elevation (July 2005): 3325m
  • Elevation given by many authorities: 3350m

    I think the official elevation is 3323m, but most authorities give 3340m+. The elevation may vary due to volcanic activity, but the most up to date GPS reading is compatible with the lower figure. The error is fairly small, but commercially motivated inflation seems likely.[3]

    Cima di e Follicie, North Corsica

  • True elevation: 1324m
  • Older Elevation, still sometimes quoted : 1305m

    Despite what is stated by some older authorities, this summit is 1324m high, and this summit, not nearby Monte Stello (1307m), is the high point of Corsica's northern peninsula. Source: official French 100k and 25k mapping, and SRTM. [3][4]


    UNITED STATES


    I am not aware of any significant elevation inflation in the US, but two commercially motivated falsehoods about visible area have come to my attention.

    Mount Diablo, near San Francisco, California more information

  • Claimed: That the visible area is second in the world only to Kilimanjaro.
  • Truth: The visible area is about one third of the area visible from Denali.[6][9]

    Rock City, Lookout Mountain, Georgia more information

  • Claimed: That Seven States (GA,TN,AL,NC,SC,KY,VA) are visible.
  • Truth: SC,KY,VA are beyond the horizon created by the curvature of the earth. Even NC is only just visible. Download Panoramic Map of visible features.




    UNITED KINGDOM


    I am no more aware of significant elevation inflation in the UK than in the US, but an old claim that Snowdon, the highest mountain in Wales, is visible from The Wrekin, is supported by a Wrekin summit indicator. There is no line of sight between the Wrekin and Snowdon. A detailed analysis of the claim's long history, written and supplied by David Squires, makes interesting reading. It shows how easily myths can be reproduced and become accepted fact.



    Elevation Precision. Some authorities quote an elevation for Everest of 8850m, as against the older 8848m, and elevations for Mont Blanc vary from 4807m to 4810m. Similar examples can be easily found.

    In spite of my comments about accuracy at the top of this page, my personal view on the above and similar examples is that, while errors in excess of 20m should definitely be exposed, and smaller errors should be exposed if they create incorrect highpoints, it is neither necessary nor always possible to determine elevations to the nearest metre. I can think of several reasons for this.

  • Sea level varies with tide. A mean tide datum is used, but in reality elevation above the sea level at any particular time will not precisely match this mean level.
  • Elevations are measured relative to the earth's geoid, not its ellipsoid. See here for an explanation of this[3]. Despite the huge number of variables that are used to determine the geoid, I am not sure that it has everywhere been determined to metre accuracy. I think that some Californian elevations are currently under review, and the margins run into metres [6].
  • Where a summit is subject to seasonal or perennial ice or snow cover, the summit elevation is subject to seasonal and weather variations. For a study of this effect on Mont Blanc, see here[7]. Until the recent round of global warming, Glittertinden competed seasonally with Galdhøpiggen to be Scandinavia's HP[3].
  • Volcanic activities ensure that some elevations are dynamic. Extreme cases like Mount St Helens are uncommon, but sporadic eruption and erosion can have a significant effect.
  • What I think the geologists call plate tectonics can create vertical movement running into metres over lifetimes.


    GPS. The US military Global Positioning System consists of a fleet of satellites. Hand held devices which can communicate with these satellites to determine position and elevation to an accuracy of about 10 metres can be obtained from most outdoor shops. When using a GPS device to determine elevation, it is important to ensure that:

  • It is tuned in to the satellites, rather than barometric pressure, which varies with time as well as elevation.
  • It is calibrated to allow for the variations between the earth's ellipsoid and geoid. See here for an explanation. Modern devices have this built in, but older ones do not and this can result in errors of up to 50 metres; see here for further information [8].
  • The batteries used to power them can withstand the temperature ranges to which they are liable to be exposed. A few months ago I suffered GPS and digital camera failure on a Scottish summit in sub-zero temperature.


    SRTM. The Shuttle Radar Topography Mission was flown by the space shuttle Endeavour for eleven days in February 2000. Apart from areas north of 60° of latitude and south of 56°S of latitude, and unfortunately some areas of very high relief and a few desert areas, the mission provided digital elevation data for the whole world. Its resolution of three arc seconds (about 90 metres), and it is in the public domain.

    The SRTM website data page claims that the SRTM cells have vertical accuracy better than 16m with 90% confidence. My work on SRTM data has compelled me to examine this data very closely and in particular to compare it with official mapping. Here are my conclusions.

    1. Subject to paragraph 4 below, the SRTM accuracy claims generally hold good. In particular, comparison in the Himalayas with both the 50k Finnmaps of Nepal and 100k Chinese Snow Mountain Maps shows consistently good correlation over large areas, suggesting the good quality of all three sources. I have also found that on former USSR territory, there is excellect correlation with Soviet topographic maps. There are no reasons to believe elsewhere in the world the data quality is different. This leads me to believe that the SRTM cells in the high Atacama Andes disprove several official Argentine elevations. But for areas of high relief, elevation variations between cells exceed 16m. For steep summits, even where there are no void SRTM cells, the highest SRTM cell may fall short of the summit elevation by as much as 50m. Obviously where the summit cells are SRTM void this will increase (the highest SRTM cell in the K2 area falls below 7000m but is 8600m in my SRTM-plus data).

    2. As the SRTM website admits, There are some rogue SRTM spikes and wells, but these tend to be small, localised, infrequent and do not tend to occur along summit ridges.

    3. As the SRTM website also admits, where "islands" of non-void SRTM data occur in "lakes" of void SRTM data, "phase" errors can and do occur. A glaring example of this is Monte Roraima, around the Venezuela-Brazil-Guyana triple point. This mountain has a large flat plateau, defended by cliffs on all sides. The cliffs have not been mapped by SRTM, and within them SRTM have deflated the plateau by about 400 metres.

    4. Where the elevation of SRTM cells substantially exceeds those of cells on surrounding plains or valleys, areas containing SRTM cells that understate their true elevation by as much as 25 metres are not uncommon, even on locally flat ridges and plateaux. Comparison of SRTM data with Swiss Alpine mapping, whose accuracy is rightly revered, has shown this up. Comparison with GPS waypoint data from the Ladakh area of North India showed this too [9]. These errors are small compared with the errors in topographical data for the Indian Himalaya from other sources; SRTM is by far the best general source of this. But the margins stretch beyond SRTM's stated accuracy specifications. By contrast, on plains, accuracy is significantly better than these specifications.

    For more information about SRTM data, go to the SRTM website. For more information about my project to correct the above-mentioned SRTM errors and fill the SRTM void no-data areas, click here.


    Acknowlegements: I thank the following for drawing my attention, directly or otherwise, to some of these errors: [1] Eberhard Jurgalski, Germany; [2] Adam Helman, California; [3] Petter Bjørstad, Norway; [4] Rob Woodall, England; [5] Janne Corax, Sweden; [6] Aaron Maizlish, California; [7] Mark Trengove, Wales; [8] Grant Hutchison, Scotland; [9] John Samson, England; [10] Arian Smit, Seattle; [11] Tamás Szabó, Hungary


    Jonathan de Ferranti. Location in Scotland N 56°20'00" W 3°15'00" ± 5". Elevation 174m ± 5m.

    Last update 12 February 2010.