-Andy Martin

In October 2004 I completed a project to list the
    50 most prominent Mountains of Mexico. The list is
    found at the bottom of this email, and at

    This write up discussed several aspects of this project:

        Climbing challenges
        Peak distribution
        Possible biological islands
        List preparation and errors

    For more info on prominence see or

            - Andy Martin, Tucson Arizona

I. Climbing Challenges

    Eight of the listed peaks are described in Kelsey's
    World Mountains guide: (number is position on prominence list)
        ( 1) Orizaba
        ( 2) Popo
        ( 3) Colima
        ( 4) Toluca
        ( 7) Diablo
        ( 9) Malinche
        (24) Ixty
        (45) Perote
    Another peak that may be known to climbers is (10) Sierra la Laguna.

    Bob Packard has climbed these, plus
    (19) Virgenes and (37) Sandia in Baja, making him the leading
    climber of these peaks to the best of my knowledge.

    This leaves about 40 peaks that are unknown to most
    hikers on the planet. The most exciting part of this
    project was looking at big peaks formerly unknown to me,
    and plotting out potential routes to the summit.

    One that looks difficult is (26) Sierra el Cerro Azul, a possible
    ultra at 4,921+ 131. This summit is isolated, has steep flanks, and
    probably is covered by dense vegetation, as it lies in the'

    There are also some challenging desert peaks near Monterrey
    that appear to require 5,000 feet vertical gain while
    bush wacking up rugged limestone terrain. The Monterrey region boasts
    the densest cluster of peaks on this list, claiming nine
    of the 50 within 75 miles of the city. Monterrey is
    perhaps 300 miles from San Antonio Texas, and thus these
    Texans are the best situated to explore big prominence
    peaks in Mexico.

    On the opposite extreme of difficulty, the interestingly
    named (25) Volcan de Tequila near Guadalajara has a microwave
    access road to top.

    It is interesting for me to contemplate the "future"
    of this list. The high point list of the 32 Mexican States
    (16 have big prominence) was published in 1991 and has attracted
    little interest to date. Hopefully this new list will have at least
    one climber tackle it in the next decade.

II. Peak Distribution

    Plotting the first fourteen peaks listed (these have 6K prominence)
    identifies four major areas with big peaks.

    The most striking is a belt of 5 big volcanos slashing
    from coast to coast through Mexico City. From west to east
    they are (3) Colima, (4) Toluca, (2) Popo, (9) Malinche and (1) Orizaba.

    Just south of this following the coastline are 3 big "unknown"
    peaks (8) Conchas, (5) Tiotepec, and (6) Nacimiento/Flan.

    Near Monterrey are (11) Madera, (12) Chena, and (14) Rafael/Morro.
    Rafael/Morro is over 12,000 feet high and has great
    "isolation", being over 300 miles from any other peaks
    reaching this height.

    Baja is anchored at the top by (6) Diablo and bottom
    by (10) Laguna.

    One surprise is the lack of big peaks in NW Mexico,
    This part of Mexico is made up of Sonora,
    Chihuahua and Sinaloa, and is a rugged land with many peaks
    over 9,000' elevation and big canyons. However, it has very
    little in the way of big prominence, with only the little
    known (49) Sierra Alamos and even lesser known (43) Cerro
    Los Algodones making the top 50 cut of 4,265 feet prominence.
    By comparison, Arizona has 9 peaks that surpass this standard.

III. Possible Biological Islands

    Prominence is a useful tool to identify biological "islands",
    with plants and animals isolated on high ground that is surrounded
    on all sides by much lower terrain. Often these areas
    harbor unique species.

    Other factors that we look for here are peaks with large
    areas of high ground, as opposed to a sharp summit.
    We expect peaks surrounded by large rivers or even oceans
    to have more biological isolation. Finally, peaks that
    have tops far above timber line, perhaps even glaciated,
    will not have as many species living near the summit.

    Taking these factors into consideration and looking only
    at the top ten peaks listed, possible biological islands are:
    Cerro Tiotepec
    Picacho del Diablo, in northern Baja.
        A large area of high ground lies to the west of the peak.
    Cerro las Conchas
    HP Sierra la Laguna, at tip of Baja, and surrounded by ocean
        on 3 sides. Known to have unique species.

IV. List Preparation and Errors

    The University of Arizona has a very good collection of
    1:50,000 scale maps for all of Mexico. I relied on these
    for elevation and naming information. These were
    prepared by the Mexican mapping agency in the 1970s and
    1980s time period. They normally use 20 meter contours
    in mountain areas, and 10 meters in flat lying ground.
    I have found them to be fairly accurate on a few
    hikes south of the border, though they can "hide"
    bothersome cliffs in some cases.

    Road info on these maps is not always reliable.
    Mexican place names seem to be somewhat variable,
    and it is unknown if the names found on the 1:50K
    maps are the most authoritative.

    My biggest problem with these maps was the lack
    of spot elevations. Most do not have a single spot
    or benchmark elevation on the quad, but only labels
    on the 100 meter index contours. Sometimes
    the 100 meter labels are incorrect, which of course
    causes problems.

    The lack of spot elevations on peaks or saddles
    means that most prominence values fall into 20
    meter (65.6 feet) "brackets". This leads to lots
    of ties of course, and helps explain why six
    peaks below the top 50 cut off are still possible
    members of the top 50 set. Note that saddle elevations
    are not listed, but can be computed by subtracting
    prominence from summit elevation. For example,
    on Popo we have:
            summit: 17716+ 66
               -  prom:  9908+ 131
                saddle   7808- 66

    This means the Popo saddle lies up to 20 meters under
    the 2380 contour shown on the 1:50K map. The summit has
    an minimum elevation of 5400 meters, with up to 20
    meters additional height. The minimum prominence  
    is 3020 meters, with up to 40 additional meters possible.

    While the 1:50K maps were essential to provide detailed
    peak information, I also relied on the 1:500,000 scale
    Defense Mapping Agency Aerospace maps purchased from NOAA.
    My set dates from the mid 1980s, and was used in identifying
    which peaks might have 4,000' prominence, and thus required
    further checking on the Mexican quads. These air maps usually
    have elevations given for summits, but these values
    differed widely from the 1:50K values. Usually they are
    higher, as you would expect on air maps. However,
    on (31) Zamorano, the air map (TPC J-24B) shows 10,760'
    and the Mexican map has 11,023+ 66. Hopefully pilots
    using the air map elevation in the vicinity of Zamorano
    are flying extra rugged aircraft ;)

    This same air map shows a major river flowing up and
    over an important saddle just south of lake San Ignacio
    Allende, 40 miles west of Zamorano. The Mexican topos do a much
    better job here, showing the river flowing through
    a canyon, and relocating the saddle to the world of fantasy.
    Users of my Mexican State HP list will note that in 1991
    a greater reliance was placed on air map elevations. However,
    a lot of quads were scrutinized since then.

    In a list of this sort my main concern is that a peak
    was accidentally left off, due either to a glitch in the
    air maps, or inadequate screening on my part. It
    would not surprise me to learn that a peak or two
    was not listed. However, Jonathan deFerranti has used a
    computer program processing SRTM data to independently
    list almost 40 of the peaks, without detecting an omission.
    In the future he plans to list peak in Mexico down to
    2,000' prominence, which will allow a complete double

    Finally, those interested in an "eyeball bender" exercise
    can try to find the key saddle 5,052- (66) for peak
    (40) Cerro Tzontehuitz on quad E15D84.
    The flat lying karst terrain makes this a challenge.