After visiting Monument Valley on the Navajo reservation in Arizona multiple times, I had the opportunity to go with a local group to an area known as Hunts Mesa. The view from the top was magnificent. We camped overnight, and awoke to the sound of coyotes howling from all corners of the valley. Rarely visited by outsiders, this is a place I would be unlikely to find on my own. The purpose of this project is to utilize the IDRISI GIS mapping program to identify exact coordinates and distances from topographic maps. My goal is to be able to revisit exact locations in the future by inputting the coordinates into a hand-held GPS unit, and determining exact travel distances. By selecting the correct metadata for the original topographic map after it has been scanned and input into the IDRISI program, this information is easily extracted. The purpose of this project is also to show some really cool photos of the area.
Monument Valley is a fascinating place. Located in the northeast corner of Arizona and extending into Utah, the Valley is a spectacular example of erosional forces taking place throughout the geologic history of the Earth. When John Ford, the famed movie producer of countless Western films, first discovered the region, he returned repeatedly to use the rock formations as a backdrop for his productions. Some formations even bear the names of Western actors, including John Wayne. One visit to this place, and the reasons are obvious.Return to top
Ruins found throughout the region reveal a rich history of occupation by the ancestors of the Navajo. Part of the Four Corners region, the landscape is dotted with Paleo-Indian sites, dating back to at least the twelfth century. Recent research, however, may eventually prove that man has inhabited such regions of the Southwest for over 20 thousand years. Some ruins were used for homes, while others were for food storage, as both human and animal predators were of concern. Also abundant in the region are petroglyphs and pictographs. The former are produced via the removal, or scratching away, of the desert varnish, or patina formed as the iron oxides on the surface of the sandstone formations oxidize. The latter refers to artwork resulting from the application of plant and animal pigments directly onto the rock walls. Incidentally, petroglyphs can be dated by comparing the amount of reoxidation that has taken place on a section of rock that was previously scraped clean by a "paleo-artist".
Notice the panel to the left displaying multiple hand imprints, perhaps done by children. Also observe the different depictions of the well-known Kokopelli character of Native American folklore. He is generally regarded as a symbol of fertility. Often the flute is portrayed as an extension of his anatomy. Most of these images were produced by carefully pecking away at the surface of the rock face with two stones, one used to drive the other as with a hammer and chisel.
Below are some local Navajo children, perhaps distant ancestors of the ancient artists. As you can see, the location is fascinating, but roads into the interior are poor to non-existent. Accurate GPS coordinates obtained from the IDRISI program could be quite useful for navigating such an area to find the way back to previously visited, but poorly marked spots.
Much of this region is made up of eolian sandstone of the Kayenta Formation. This type of sandstone was deposited primarily by the wind, and as such is prone to erode into arch formations, often considered sacred by native peoples.Return to top
I began by scanning in a section of an Arizona topographic map. This was easily imported into the IDRISI program using the "Desktop Publishing Format" and selecting "JPGIDRIS". I imported two versions, one for coordinates and one for distances. For the coordinate version, I used the boundaries of the map section scanned to alter the metadata for this version to reflect the exact coordinates. The topographic map clearly shows specific gridlines. It is most convenient to crop the scanned sections so that the boundaries of that section coincide exactly with the chosen grid lines which are labeled with latitude and longitude values in degrees. These boundaries, which delineate the region of interest, are used in the metadata to specify minimum and maximum "x" and "y" values. At this point, IDRISI will calculate the exact coordinates of any point on the map selected with the cursor. The other version of the map section is used for distances. Careful measurement of the scanned section is used to determine the horizontal and vertical distance described. Using "0" for the minimum "x" and "y" values, and the actual horizontal and vertical distance for the maximum "x" and "y" values respectively, any distance on the map from one feature to another can be precisely calculated using the Pythagorean Theorem. The square of the distance desired is equal to the sum of the squares of the horizontal and vertical distances. Positioning the cursor over a precise location on this map reveals both components of the distance from the origin at the lower left corner of the map section. The difference between two "x" measurements as compared to the origin gives the "delta x". The same is true for the "delta y" reading. Square these two readings, add them together and take the square root to get the precise distance between map points. The calculations are simple, and more precise than merely measuring distances on the original printed topographic map.
The image above left is the distance image, and the scale bar is in kilometers. The image on the right is for coordinates, and the scale bar is in degrees. The images are virtually identical, but the metadata for each has been altered to give very different information. Together they supply sufficient parameters to locate any point on the map with precise distances from access roads and well-known landmarks. Below left is a magnified version showing more details of the Monument Valley topography, and below right is a more greatly magnified section focussed on Hunts Mesa. Even when zooming in on a specific location of the map, IDRISI maintains the correct coordinates for any selected point. In this case, Hunts Mesa is located at a latitude of 36.88 degrees and a longitude of 110.04. Calculating distances, from the nearest town of Kayenta at the intersection of routes 163 and 591, Hunts Mesa is located at a "delta x" of 19.40 km and a "delta y" of 17.31 km. Adding the squares and taking the square root of the sum gives a linear distance of exactly 26.00 km. Doing the same for the nearest road, route 160, yields a distance of 12.06 km.As you can see, this is a harsh environment, and one would not want to get lost! Also, since this is tribal land, access is limited to those with a local guide who is a member of the tribe. Reservation lands are regulated by local government, and should not be treated as public. Obey all rules and don't disturb any cultural or archeological sites. Return to top
This approach to using IDRISI for extracting exact coordinates and distances from scanned topographic maps is just an example of how the casual hiker can be more efficient, and safer, when attempting to explore the less developed regions of the backcountry. This approach, as previously discussed, is a great way to revisit a location when precise coordinates and relationships to landmarks are not well known. Especially when the terrain is dry, and all water must be carried in, precise planning is essential. A slight miscalculation in such an environment can be deadly. On one occasion, a simple compass bearring taken at the beginning of a trip directed myself and a hiking companion back to our vehicle after being hopelessly lost. With exact coordinates input into a handheld GPS unit and precise distance measurements, the chances of a safe return are greatly improved.
Prehistoric Indians; Their Cultures, Ruins, Artifacts and Rock Art, Barnes and Pendleton, 1979
Ancient Ruins of the Southwest, David Grant Noble, 1991
Hiking the Southwest's Geology, Ralph Lee Hopkins, 2002
Hiking the Southwest"s Canyon Country, Sandra Hinchman, 1990
Journey to the High Southwest, Robert L. Casey, 1983
Native Roads, Fran Kosik, 1996
Arizona Traveler's Handbook, Bill Weir, 1992
All Photos of Monument Valley by Larry Kuss