Northern Arizona's Hidden Faults
Overview: Lying unnoticed and undisturbed by the millions of travelers that pass within 400 yards one of its surface openings each year, the Leupp Faults lay quietly awaiting your inquisitive visit. The seemingly featureless high desert plain lying east of Flagstaff, west of Winslow and south of the Little Colorado River is not as boring as it might first appear. These faults generally run from northwest to southeast and are not difficult to access for those willing to seek them out. Much of the length of the fault is identifiable on the surface but is not open to entry and exploration, it is merely a surface depression that follows the fissure below. There are several locations however where the faults open up as gaping chasms that interrupt the smooth surface of this treeless and windswept rolling prairie.
Historical Note: At the bottom of the fissure openings that lie closest to I-40 we found a treasure of sorts. As near as I can estimate, sometime about 50 to 60 years ago, someone decided to use the open fissures as a disposal site for a large quantity (20 - 30) of the old wooden hand crank box style phones that had the mouthpiece and bells mounted to the front and the ear piece hanging from a hook on the side. I assume that when the phone systems serving local ranches or possibly from somewhere else were upgraded, the technician or contractor used the fissure as a cheap, convenient disposal site for all of the old phones and their associated dry cell batteries. Unfortunately time has taken its toll and the phones are beyond salvage in my view, but it was interesting to look through the piles of decomposed remains and ponder long lost conversations and news passed around the country with these old phones.
Geologic Description: (quoted from the USGS Earthquake Hazards Program) "These predominantly northwest-trending normal faults are at the easternmost edge of and beyond the Pliocene-Quaternary San Francisco volcanic field in north-central Arizona. They are on the erosion surface cut on Paleozoic rocks that slopes north from the Colorado Plateau margin to the Little Colorado River. The faults cut Paleozoic and Mesozoic bedrock, locally middle Pleistocene basalt, and Quaternary alluvium. Displacement is primarily down-to-the-northeast or east. The faults have been active in the middle or late Quaternary, but the age of youngest movement is not well constrained."
Hike/Climb: This exploration will require the gear, knowledge and ability to rappel down into the fissures to depths from 50 to 100 feet and then climb back out, either up the walls of the fissure or up your rope. If you are interested in seeing the faults but are unable to make the decent into their depths they are still worth visiting to be viewed from the surface. I will note however that my 62 year old mother has rappelled into one of the deeper openings (at age 62)! We did provide mechanical assistance in extracting her from the fissure, which certainly is an option open to you as well. I believe that a large part of my sense of adventure comes from my mom. She is currently planning a skydiving with us next spring at age 65!
Once on the floor of the fissures you can generally travel horizontally in either direction for up to several hundred feet or more. Along the length of the faults there are numerous skeletons and semi decomposed carcasses of various small animals and reptiles that have fallen into the fissure never to return to the surface. There are numerous bats that reside peacefully within the fissure, some hanging upside down from the rough surfaces of the fissure walls and others occasionally tucked cozily into small nooks and holes that pockmark the walls of the fissure.
According to the USGS fault maps the Leupp Faults extend to the north of I-40 as well. I have not explored this area on the ground however the available aerial photos of the area do not indicate the exposed segments that are present south of the freeway. For an excellent view of the faults, use the dynamic map feature on HAZ and select the aerial view of the indicated coordinates.
Caution: There are no railings, fences or other protection around the open faults. Use extreme caution near the holes and closely supervise children and animals. A fall could be fatal.
WARNING! Hiking and outdoor related sports can be dangerous. Be responsible and prepare for the trip. Study the area you are entering and plan accordingly. Dress for the current and unexpected weather changes. Take plenty of water. Never go alone. Make an itinerary with your plan(s), route(s), destination(s) and expected return time. Give your itinerary to trusted family and/or friends.