casitas de gila guesthouses bed and breakfast new mexico 575-535-4455

Southwestern Guesthouses on 265 Acres
near Silver City, New Mexico
overlooking Bear Creek and the Gila Wilderness

Casitas de Gila Nature Blog

Casitas de Gila Nature Blog


A Day Hike to the San Francisco Hot Springs and the Pristine Wilderness of the San Francisco River Canyon

San Francisco River Canyon New Mexico

Looking west down into the San Francisco Canyon where the floodplain narrows and the river enters deeply-incised meanders

The San Francisco River is the largest tributary to the Gila River. Over its 160-mile course, it flows through some of the most scenic country in Southeastern Arizona and Southwestern New Mexico. Emerging from its mountainous headwaters near Alpine, Arizona, in eastern Apache County, the San Francisco flows eastward into New Mexico’s Catron County before looping south and then westward back into Arizona, where it joins the Gila River a few miles downstream from the historic town of Clifton in Greenlee County. Along its course, the San Francisco flows through diverse landscapes, alternating between sparsely settled, broad, open valleys, ranched and farmed since the pioneer days of the late 1800s; and narrow, rugged, deeply-incised canyons of pristine wilderness, once the familiar and well traveled thoroughfare of a hundred or more generations of Native Americans, but rarely visited today.

For much of its course through New Mexico, the San Francisco River flows through Gila National Forest land where various forest roads and trails provide public access points to the river within a rugged, mountainous terrain. But it is the last 15 miles of its New Mexican sojourn, just before reentering Arizona, where the San Francisco travels the most remote, isolated, and inaccessible segment of its journey. It is along this stretch of river that the San Francisco descends into a wild and pristine canyon comprised of an increasingly narrower and deeper series of tightly looped, entrenched meanders as it traverses an uplifted complex landscape of Miocene and Oligocene layered volcanic deposits over a thousand feet in thickness and some 18-26 million years old1.

It is at the upstream entrance to this deeply entrenched and narrow canyon that the San Francisco Hot Springs Trail is located.


San Francisco Hot Springs New Mexico

US Forest Service kiosk at the trailhead to San Francisco Hot Springs

Of the numerous hot springs that occur throughout the Gila National Forest, the San Francisco Hot Springs group is one of the better known and more easily visited. The springs are located about 8 miles south of Glenwood, New Mexico (about 35 minutes northwest of Casitas de Gila Guesthouses). They are readily accessed from a half-mile long, county-maintained gravel road leading from US Route 180 to the trailhead for the San Francisco Hot Springs Trail. The trail to the hot springs is a 1.5-mile moderately-difficult hiking trail leading down into the magnificent San Francisco River Canyon where the springs are located.

The San Francisco Hot Springs consist of three separate groups of springs that are spread out along a quarter-mile of the river floodplain. The Upper Group of hot springs occur on private property, just north of the Gila National Forest boundary, and provide water to the privately-owned Sundial Springs. The Middle and Lower Group of springs are on Gila National Forest land immediately downstream from the Upper Group, and are accessible from the San Francisco Hot Springs Trail. Temperature of the springs is reported to range from 100 to 120°F depending upon the stage of river flow2.

The Middle Group of hot springs, sometimes referred to as “The Bubbles”, occurs against a rock cliff on the west side of the river, directly across from where the San Francisco Hot Spring Trail comes down to the river.

The Lower Group of hot springs occurs about 450 feet south of the Middle Group and is also located on the opposite side of the river, right where the canyon and river make a sharp turn to the west.

Like many of the hot springs found in the Gila National Forest, the San Francisco Hot Springs are located within the floodplain, at the bottom of a canyon, and are associated with a major fault, which in this case is the NNW trending Sundial Mountain Fault1, which crosses the San Francisco River canyon right at the Lower Hot Springs. The Sundial Mountain Fault is a high-angle dip-slip normal fault, dipping NE between 60 and 80°, and most probably serves as the conduit for the hot waters ascending from deep within the earth.

Because the San Francisco Hot Springs are located within the floodplain of the river, with several being right at the river’s edge, the exact location, size, and even the actual presence of the various springs will vary from year to year depending upon the number and magnitude of flood events on the river. During consecutive years of few or less-intense flood events, visitors to the springs will typically construct rock-lined pools around the emanating hot springs, which will serve as sitting pools until the next flood wipes them away, and the construction of new pools commences. However during the more severe flood events, it is often the case that the river channel will experience significant lateral movement, sometimes moving completely from one side of the canyon to the other. During these times, returning visitors may find that their favorite hot springs have been buried completely by the migrating river deposits, and then discover that new springs have emerged nearby.

It seems important to conclude this overview on the nature of the San Francisco Hot Springs by stating that a trip to the San Francisco Hot Springs is almost always a great hike even if the Springs themselves are not at their best for the reasons stated above. The scenery is gorgeous, the rugged and pristine San Francisco River Canyon downstream from the Springs is spectacular, intriguing, and challenging, and the bird and animal populations abundant and diverse. High water during the spring runoff (February through April), or the summer monsoon season (July through mid/late September) will sometimes limit trail access and prohibit river crossings, but during other months of the year it is not generally a problem for those interested in a longer hike down the river. For those looking for a short, easy to moderate, yet highly interesting hike through a diverse and unique landscape, a visit to the San Francisco Hot Springs area is highly recommended.


San Francisco River Canyon New Mexico

Looking northwest at the top of the San Francisco Canyon where the trail begins its steep descent to the river below

And thus it was, one late August day last month, that my good friend Bill Marcy and I decided to spend some time hiking and exploring in the San Francisco Hot Springs area and to check on the status of where the springs might be now. Bill had been there before, but I had not, despite having known of them and been told numerous times about how interesting the area is. While I am not a hot springs soaking enthusiast, as a geologist I find them fascinating and over the years have developed a strong interest in the geology and hydrology of their occurrence.

Now August, of course, is generally the peak of Southwest New Mexico’s Monsoon Season, but we weren’t at all concerned since the summer monsoon showers and thunderstorms, while they can be intense at times, generally don’t last more than half an hour before the sun comes out again to dry everything. Plus, according to the National Weather Service, the probability of rain for that day was only 40%. And so, without further thought, I packed my gear and lunch, drove over to Bill’s, where we loaded our two dogs, Big Red and Bower, into Bill’s truck and headed out.

A morning’s drive up US 180 towards Glenwood is always a gorgeous trip, with the ancient Burro Mountains rising to the south and the vast ramparts of the towering Mogollon Mountains of the Gila Wilderness to the north, glistening and beckoning in the morning sun. This morning was no different. At least it started out that way. However, after about a half hour’s journey, we noticed that the Mogollons were no longer glistening. In fact they were actually looking rather dark and foreboding, their higher peaks shrouded in rain clouds. Looking ahead towards the mountains surrounding our destination, the sky seemed to be even darker. But, no matter, the mountains and the open trail were calling and we were on our way!

Arriving at the San Francisco Hot Spring trailhead, we both noticed that the dark clouds were indeed now quite a bit darker, borderline black maybe, and seemed to have taken on a sort of roiling motion as well. But the call of the open trail was even louder now, so we hoisted our packs and headed out.


San Francisco Hot Springs Trail

The trail leading to the San Francisco River Canyon

The first mile of the San Francisco Hot Springs trail follows a gently downhill sloping grass-covered arroyo, dotted with numerous Alligator Juniper (Juniperus deppeana), Piñon Pine (Pinus edulis), Honey Mesquite (Prosipus glandulosa), and Desert Scrub Oak (Quercus turbinella) trees. The trail itself is impossible to miss, having been worn down as much as a foot into a clayey, pebble-to-boulder strewn soil by numerous hikers, cows, wildlife, and rainwater runoff over the years. As the hike progressed, we noticed with some interest that clay minerals, not all that common over most trails in our area, here seemed to be the major constituent of the trail we were walking on. Once aware of this fact, we then noticed how much of the ground and trail surface showed extensive shrinkage cracks dried out by the summer sun. “Hmmm,” murmured the scientific voice quietly within, “bet this trail gets really sticky during a hard rain!”

At about the one-mile mark the edge of the San Francisco River Canyon is reached, marked by a barbed wire stock fence with a convenient off-set stile provided for the trail to pass through. Once past the fence, the trail begins a steep, quarter-mile descent of about 200 vertical feet to the bottom of the canyon. Here, the loose clayey soil of the previous mile disappears and the trail switchbacks down a rock surface composed of hard, angular to sub-rounded cobbles and boulders of mostly dark gray volcanic andesite, which are set in a softer, fine-grained, light-colored matrix. It is an unusual rock type, and one that once exposed to weathering, produces a very rough and lumpy surface, not slippery at all, but providing excellent traction. Yet because of the way the encased cobbles and boulders protrude from the softer matrix, we quickly noticed that it can also be a somewhat treacherous surface that is easy to trip on, especially when one gets too engrossed in the magnificent view of the sheer, volcanic cliffs now lining the canyon ahead and below!

We were about halfway down this lumpy section of the trail when the first rain drops began to fall. It was also at this point that Big Red and Bower sensed the presence of the San Francisco River another 100 feet below. Water! How nice! … Our favorite thing! … Let’s go jump in! And off they went at a run, down the steep slope with their owners struggling to keep up, having just noticed with more than a little consternation that the river seemed to be running a bit high and swift.

We arrived at the river’s edge just as Bower charged in, only to discover that his point of entry is at a cut-bank of the river and he is immediately over his head. Sensing danger in the depth and strength of the current, Bower responded immediately to my frantic call, swam back, and climbed out. Big Red, the more mature and thoughtful red-bone hound that he is, had halted at the water’s edge, and watched all knowingly as his impetuous younger friend dragged himself up out of the dark swirling water and shook off. It is then we noticed that my normally white-and-brown Springer Spaniel has taken on the appearance of a very slimy, dark-chocolate-brown labrador retriever! The cause of the dark color of the water is immediately obvious. The effects of the Whitewater-Baldy fire (May-June 2012) within the Gila Wilderness were still making their way downstream … the normally crystal clear and lively waters of the San Francisco River were now a swirling, heavy, viscous torrent of very dark chocolate.

The first drops of rain had multiplied exponentially and it was now raining hard. We stood at the water’s edge where Bower had taken his brief swim and could see the Forest Service trail marker leading to the Middle Group of hot springs beckoning on the other side. But not today. The river was running very swiftly, and because we were unable to see the bottom (because of the suspended ash and soot), it was impossible to tell how deep it was. “Don’t even think about it”, advised the soft voice within.


Waiting out the downpour in the Arroyo of Little Relief. (The blurriness of this photo is not a focusing or movement problem . . . it’s because of the amount of rain cascading down upon man and beasts!)

The rain had just turned from hard to harder. To the left of where we stood another Forest Service trail marker pointed south, down-stream through a mature riverine forest, towards the imposing cliffs we had seen during our descent into the canyon. This trail, we knew, would lead to a point where under normal water level conditions the trail would once again cross the river to the Lower Group of hot springs. Visiting those hot springs would have to wait for another day, but we hurried down the trail anyway towards the towering old growth cottonwoods (Populus fremontii) where we hoped to find some shelter from the approaching center of the thunderstorm cell, which by the telltale increasing frequency and decibel level of the thunder, would soon be upon us.

Anyone who has spent much time in the Southwest knows all too well the dangers of seeking shelter from a storm under old cottonwoods, particularly in the summer when they are in full foliage and their branches are heavy with water. Even in a moderate breeze on a fine sunny day their weak and brittle limbs can suddenly break off and fall to the ground, crushing anything below. But this was not a breeze; this was turning in a maelstrom of hurricane-force wind and rain. So we hurried by several big cottonwoods, taking notice of a one-foot diameter specimen freshly felled by some champion of the local beaver (Castor canadensis) population and an even more impressive and still standing, 16-inch diameter cottonwood that had been chewed all the way through except for a thin, 2-inch thick portion on one side. Now there was a real beaver trap … craftily set for unsuspecting humans!

San Francisco Hot Springs New Mexico

The spectacular cliff where we should have waited out the storm

Just as the rain turned from harder to hardest, the trail passed by a small, narrow, and steep-sided arroyo with a gnarled Desert Scrub Oak (Quercus turbinella) spreading a thick canopy of non-lethal little branches that partly shielded the slightly undercut north side of the gravel bank of the arroyo. Thinking we could do no better, we decided to hunker down here to wait out the storm. No sooner was the decision made and we started to take off our packs when a lightening bolt struck the rocky slope of the canyon wall above us, less than a hundred feet away, with a simultaneous, resounding crack of thunder that made all four of us jump while simultaneously eliciting various yells, howls, and whimpers. The center of the storm had arrived. And along with it came an immediate change in wind direction and a crescendo of pounding rain that converted our once seemingly-protected spot into something akin to being trapped at the bottom of a giant waterfall.

But just as we felt we were going under for the third time, it was over. In a few minutes, the clouds began to brighten and it seemed that the sun was considering an appearance. Encouraged, we decided to follow the trail a little further. Soaked and chilled to the bone by the now 20 degree cooler temperature, the thought of moving was inviting.

San Francisco Hot Springs New Mexico

Negotiating the ledge at the water’s edge

Just past the mouth of our small arroyo-of-little-relief, we were immediately confronted with a 50-foot section where the the trail suddenly disappeared, submerged by the swollen river that was now running hard up against a steep bank of very loosely consolidated, slippery, fine-grained silty material that was slowly eroding into the creek. After some serious cogitation of the situation, we convinced ourselves that the one-foot-wide rocky ledge that was slightly awash at creek level should enable us to make our way safely across. It did. Once on the other side, the trail re-emerged to once again enter a widened floodplain, substantially vegetated with mature cottonwoods and other trees. A short distance into this forested floodplain, the trail leads to an impressive and visually-striking vertical cliff of horizontal beds comprised of two very different and distinctive rock types. The lower 10 to 13 feet of the cliff consists of loosely consolidated fine-grained material, similar to what we had just passed over at the water’s edge, which has been eroded and weathered back at least a good 5 to 10 feet beneath an imposing overhanging layer of undetermined thickness composed of angular to sub-rounded, dark-colored cobbles and boulders of mostly andesite, set in a light tan, fine-grained matrix, very similar to what we had passed over on the steep portion of the trail on our descent into the canyon. Here was were we should have waited out the storm!

The skies had once again turned black and with the sound of thunder we knew another storm was approaching from the south-southwest. It was time to turn around and head back.The threat of another soaking was not the problem. The real concern was that the storms in the area seemed to be intensifying as the afternoon wore on and were tracking right over the western end of the highest section of the Mogollon Mountains, upstream and to the north of us, where the duration and amount of rainfall we knew would typically be greater and would soon be draining directly into the San Francisco River upstream from us. The likelihood of a flash flood was increasing by the minute, and because we were now downstream from the difficult spot we had just crossed at water’s edge, even a two- to three-foot rise in river level could prove to be very problematic. Knowing that having reached the spectacular cliff in front of us, we were now no more than a quarter-mile from entering the deeply entrenched, cliff-lined meanders of the San Francisco River, it was really tempting to continue. But it would have to wait for another day. Once more the little voice within was speaking out, “No! It’s time to go! Get the heck out of here!”

Examination of Ratte and Brooks’ 1989 geologic map of the San Francisco Hot Springs area1 shows that all of the San Francisco Hot Springs trail we had just traversed, from the trailhead to our turn-around point at the spectacular vertical cliff described above, is mapped as a locally derived, over-600-foot-thick fanglomerate deposit within the Gila Conglomerate Formation of Pleistocene to Miocene age, which occurs on the east, down-dropped side of the Sundial Mountain Fault described earlier. Had we continued our hike just a few hundred feet to the west of our turn-around point, we would have crossed the Sundial Mountain Fault and passed into the layered volcanic deposits of the Upper Andesite member of the Bearwallow Formation. This Upper Andesite Member, which has been dated at being 24.7 million years old, is the source of the fanglomerate deposit on the east side of the fault. The fanglomerate deposit was formed when the Upper Andesite deposits were being uplifted and eroded on the west side of the intermittently active Sundial Mountain Fault, and the eroded material was then being transported by streams to the east across the fault, where it was quickly deposited as coalescing alluvial fans in a rapidly subsiding down-dropped elongated basin or graben, between the northern Burro Mountains on the West and the Mogollon Mountains on the east. In the geological literature this basin is known as the Mangas Trench, and is one of several NW trending basins in the surrounding region of New Mexico and Arizona. Based on dating of various basalt deposits within these basins, the faulting along the margins of these down-dropped basins began shortly after 19 million years ago, and persisted intermittently for millions of years, allowing thick deposition of alluvial sedimentary deposits consisting mostly of conglomerates, fanglomerates, and sandstones derived from the uplifted surrounding mountains3.

San Francisco Hot Springs Trail New Mexico

An army of lichen-covered andesite boulders captured in their inexorable creep through time and space down the northeast slope of Sundial Mountain

The initial part of the trip back out of the canyon went quickly as the next storm progressed slowly towards us. However once the top of the canyon was reached, our pace of travel slowed considerably as the trail wound its way uphill, across the mile of cobbles and boulders embedded in the heavy, clay-rich soil. The once firm, mud-cracked ground surface commented on during our hike in was not so firm anymore, and once again the little voice had been right. The going had now rapidly progressed from sticky to stickier, and finally to extremely sticky … And with every step, the size and weight of our cleated boots became larger and heavier, reminiscent of one of those dreams where no matter how hard you try, your feet and legs will hardly move and you can’t seem to get away or make any progress.

Eventually the homeward slog ended and we reached the trailhead, where several pounds of sticky clay was scraped off. After a short but most welcomed and enjoyable lunch, we loaded up the dogs and headed for home, just as the first drops of rain from the arriving thunderstorm began to splatter on the windshield. Indeed, it had been an “interesting” day.

San Francisco Hot Springs Trail New Mexico

The trail through clay and boulders starting to get sticky

San Francisco Hot Springs New Mexico

A top contender for the Best in the West “Outhouse with a View” Award, here looking north towards the magnificent Mogollon Mountains


The San Francisco Hot Springs trailhead is located at the end of a one-half-mile long, county maintained, all weather, gravel access road that leaves US Route 180 around Mile Marker 58, a point 6.5 miles south of the road entrance to the Glenwood District Ranger Station and 5 miles north of the turnoff on US 180 for the Leopold Vista Overlook rest area. GPS coordinates for the access road turnoff leading to the trailhead are N33°14.025′, W108°51.651′. A newly-constructed restroom building is available at the trailhead, but water is not.


1. Ratte, J.C. and Brooks, W.E., 1989, Geologic Map of the Wilson Mountain Quadrangle, Catron and Grant Counties, New Mexico: U.S. Geological Survey, Geologic Quadrangle Map GQ-1611.d

2. Bischoff, Matt C., 2008, Touring New Mexico Hot Springs, 2nd edition

3. Houser, B.B., 1994, Geology of the Late Cenozoic Alma Basin, New Mexico and Arizona, New Mexico Geological Society Guidebook (download .pdf file), 45th Field Conference, Mogollon Slope, West-Central New Mexico and East-Central Arizona

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Forged by Fire • Treasured Through the Ages

obsidian rocks

Typical shapes of Mule Creek Marekanites; size range averages 1 to 5 cm, although some may go as large as 10 cm.

Among the wide range of volcanic rocks and minerals that can be found near Casitas de Gila Guesthouses, one of the most interesting is obsidian. In geologic terms, obsidian is classified as an extrusive igneous rock or sometimes a mineraloid, but never as a mineral because it does not have a crystalline structure. Instead it is a naturally-occurring amorphous volcanic rhyolitic glass, formed when a magma or lava flow, highly rich in SiO2 cools so rapidly that crystalline minerals do not have time to form. Typically, obsidian contains between 70 and 75% SiO2, substantial amounts of magnesium oxide (MgO) and iron oxide (Fe3O4), plus numerous trace elements, such as rubidium (Rb), cesium (Cs), strontium (Sr), barium (Ba), lanthanum (La), cerium (Ce), yttrium (Y), titanium (Ti), zirconium (Zr), phosporous (P), tantalum (Ta) or niobium (Nb).

Obsidian is easily identified by its glassy, conchoidal fracture and its brown or smoky-gray to black color. Sometimes it may contain inclusions of small, white crystals of the mineral cristobalite, a high-temperature form of SiO2, or it may contain linear or swirling patterns of extremely small gas bubbles retained within the flowing magma or lava before it was rapidly cooled.


Perlite showing bedding layers and swirling texture

Obsidian is found around the world wherever rhyolitic magma (containing 70% or more SiO2 and less than 2% water) occur. In the United States, obsidian occurs in most western states and is abundant within western New Mexico and Arizona. Similar deposits of obsidian occur just south of the border in the Mexican States of Sonora and Chihuahua.

Obsidian is not stable at the earth’s surface and consequently is rarely found in rocks more than a few tens of millions of years old. The reason for this is that over time, ever so slowly, obsidian absorbs water into its structure, and once that happens the obsidian converts to another natural glass or mineraloid called perlite. Thus, many volcanic deposits that originally formed as obsidian are now entirely converted to perlite. Not all perlite deposits form from hydration of obsidian, however. If a rapidly cooled, rhyolitic magma contains 2% or more water to start with, then the resultant volcanic glass will solidify as perlite, not obsidian.


mule creek, new mexico

Mule Creek Country. Outcrop of rhyolitic ash flow deposit in foreground.

The geologic history of western New Mexico during the Late Paleogene to Early Neogene Periods (old terminology Mid to Late Tertiary) was basically a time of extensive and ongoing volcanic activity. By the end of Oligocene Epoch the lengthy period of massive eruptions of the Super-volcanoes within the Gila Wilderness (35-28 million years ago) had come to an end, and the focus for most of the ensuing volcanic activity within the Grant County/Catron County, NM, border area over the next 10 million years or so during the Miocene Epoch shifted westward towards the Arizona/New Mexico border and into eastern Arizona. It was during this time between 20 and 17 million years ago that the obsidian deposits of the Mule Creek region were formed.


Broken Marekanites displaying conchoidal fracture

Extensive research by M. Steven Shackley, Department of Anthropology at the University of California at Berkley, regarding archaeological sources and use of obsidian in the American Southwest indicates that the Mule Creek Obsidian Deposits are probably the most extensive occurrence geographically of obsidian anywhere in the Southwest. The deposits are located about 20 miles northwest of the Casitas and occur within a greater than 100 square mile area that centers around the small community of Mule Creek, New Mexico, about five miles from the Arizona border. Within this vast area that includes portions of Grant and Catron Counties in New Mexico and Greenlee County in Arizona, are numerous, extensive obsidian-bearing volcanic rhyolitic ash flow deposits. When found in place, the obsidian occurs as small nodules, generally two inches (5cm) or less in diameter, but occasionally up to twice that size, within outcrops of perlitic ash-flow deposits that absolute dating shows were ejected 17.7 million years ago.

marekanites in perlite matrix

Close-up of Marekanites in Perlite matrix layer within Mule Creek rhyolitic ash flow deposit

The scientific name for these obsidian nodules is marekanites which take their name from the Marekanka River in the Okhotsk basin in Siberia, Russia, where they were described over a hundred years ago. A more recent, common name that is often given to these obsidian nodules is that of “Apache tears”, a name coined by mineral collectors, rockhounds and lapidary enthusiasts for the obsidian nodules found in the American Southwest. In addition to the widely distributed outcrops of marekanite bearing perlite deposits of the Mule Creek Obsidian Deposits, the obsidian nodules also occur as a significant constituent of virtually all Quaternary Period alluvium deposits which have been eroded from the bedrock outcrops and redeposited in stream beds and valleys throughout the region.


Perlite layer

Perlite layer within Mule Creek rhyolitic ash flow

Obsidian has been a treasured natural resource of prehistoric and historic cultures worldwide since the beginning of the Stone Age because of its glassy composition and conchoidal fracture, allowing the rock to be easily worked into extremely sharp projectile points, cutting blades and other tools. Because of its limited occurrence, good sources were highly sought after by prehistoric cultures, most likely fought over, and became the basis of early production centers, commerce, and trade routes.

Archaeological research of the late pre-historic cultures of the American Southwest and Northern Mexico conducted by Dr. Shackley at the University of California at Berkley and research done as part of the Preservation Fellowship Program at the private non-profit organization Archaeology Southwest has shown that the Mule Creek Obsidian Deposits were extensively mined and utilized by early cultures, and that the raw obsidian nodules and probably partially finished products (called blanks) were widely utilized and traded within in New Mexico and Southern Arizona. The evidence for this is based on analyzing the trace element composition of obsidian artifacts, and then comparing the results with the trace element composition of known obsidian source deposits.

cross-bedded rhyolite and perlite

Mule Creek cross-bedded rhyolite and perlite ash flow deposit

Extensive analysis of numerous obsidian source areas has shown that the type, amounts of, and the ratios of various trace elements within a source area are essentially unique, and thus can be used as a diagnostic tool for determining the source of the material used in an artifact’s manufacture, as well as providing clues as to distribution patterns and possible trade routes for the raw material.

Today obsidian is still used in the manufacture of precision cutting tools such as scalpels used in surgery. The reason for this is that a fractured edge of obsidian is far sharper than any surgical steel blade manufactured. Research on the effectiveness of obsidian scalpels has shown that wounds heal faster, with less scarring, and without complications.

The use of obsidian in jewelry, stone carvings, and sculptures goes back for thousands of years and continues today, where it finds abundant use in inexpensive, mass-produced jewelry, as well as high-end artisan jewelry, and as a carving stone for sculptures.


mule creek, new mexico, obsidian

Close up of Marekanites in alluvium, weathered out of Mule Creek rhyolite and perlite ash flow deposit

For travelers who delight in taking the road less travelled, the most scenic route between the southern Arizona cities of Tucson and Phoenix and Casitas de Gila Guesthouses involves a spectacular one-hour drive through the Apache National Forest in Arizona and the Gila National Forest in New Mexico over AZ/NM Highway 78. About five miles east of the Arizona/New Mexico border, NM 78 passes through the small community of Mule Creek, which has a US Post Office (at least at the time of this writing), but no other stores. Near the sign for the post office there is a dip in the road where the typically dry Mule Creek crosses the road. For the traveller in a hurry, a one-minute stop here at the side of the road will almost always produce a couple of nice Marekanites left behind by short-term flooding of Mule Creek during periods of high runoff from the surrounding hills. For the more serious rockhound or geology afflicted souls, rest assured that longer visits into the surrounding Gila National Forest in this area can provide anywhere from a day to a lifetime of memorable geological experiences!

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Hiking New Mexico’s Gila River

Hiking the Mogollon Box Trail — Gateway to the Gila Wilderness

Gila Riparian Preserve New Mexico

Entering the Gila Riparian Preserve on the Mogollon Box Trail

A short six miles upstream from the communities of Gila and Cliff, New Mexico, the Gila River exits the soaring mountains and rugged canyons of the Mogollon Range of the Gila Wilderness within the Gila National Forest to begin a more leisurely, meandering flow westward across the verdant Gila Valley. This transition from a narrow, steep-sided, volcanic rock-lined canyon to the wide alluvial floodplain of the Gila Valley, with its magnificent bordering groves of ancient cottonwoods, sycamores and willow, is as abrupt as if it had been carved by some gigantic knife of Nature. Which, in one sense, it has, for it is here that the Gila River crosses a major east-west fault separating the uplifted terrain of the Mogollon Mountains and the Gila Wilderness from the down-dropped lowlands of the Gila Valley. This very special natural area is known as the Mogollon Box or the Upper Box of the Gila, the Gateway to the Gila Wilderness.

gila river new mexico

Looking north into the Gila Wilderness

For the hiker and nature enthusiast, the Mogollon Box Trail offers a unique opportunity to connect with an amazing diversity of topography, geology, fauna, and flora for several miles along the pristine waters and surrounding riverine forest of the Gila River. Adding to the complexity of this landscape is the presence of Mogollon Creek, which has its confluence with the Gila at this transition spot, after flowing some 20 miles in from the west, along the base of the Mogollon Mountain escarpment and its headwaters high in the 10,000- to 11,000-foot mountain peaks of the Gila Wilderness.

gila river hike, new mexico

The trail climbs a ridge carved from ancient river deposits

The Mogollon Box Trail begins by traversing a 1,200 acre parcel of land known as the Gila Riparian Preserve. Originally a privately-owned farm and ranch, bordered on all sides by the Gila National Forest, this land is now owned by the Nature Conservancy and is open to the public (map available). Animal and bird life are prolific within the Gila Riparian Preserve because of the wide diversity of available habitat, ranging from the year-round, cool, clear flow of the Gila River through quiet, deep pools and swift, gravelly shallows; to active floodplain deposits of sand and gravel, interspersed with numerous natural levees along old river channels now covered with young riverine forest; to marshy, abandoned channels and cutoffs; to sequentially elevated levels of older vegetated river terraces; to gently-rolling upland high-desert hills and ridges cut by dry-wash arroyos; to shear cliffs and ledges of volcanic bedrock … all to be found within a narrow riparian zone extending a few hundred feet either side of the Gila River itself.

Gila River Riparian Preserve

Looking north from the ridge and upstream at the Gila River Riparian Preserve

Gila Riparian Preserve, New Mexico

Descending the ridge of ancient river deposits to the modern floodplain

Arizona Alder

A shady passage beneath an old Arizona Alder (Alnus oblongifolia)

Literally hundreds of bird species frequent the Mogollon Box over the course of the year because of the dependability of food and water, including many rare and endangered species, such as the Southwestern Willow Flycatcher (Empidonax traillii extimus). Within the river and riparian zone, numerous fish, amphibians, reptiles, and mammals are found, such as the common Smallmouth Bass (Micropterus dolomieui), the boistrous Canyon Treefrog (Hyla arenicolor), the rare Gila Monster (Heloderma suspectum), and the shy Coati (Nasua narica). In addition to these, sightings of more typically upland species are common, such as Mountain Lion (Pumua concolor), Black Bear (Ursus americanus), Bighorn Sheep (Ovis canadensis) and Mule Deer (Odocoileus hemionus), as they make their way down from the surrounding hills and mountains to drink, forage and prey. As always, best sightings will be made during the hours of early morning and late afternoon to dusk.

common scouring rush

The Common Scouring Rush (Equisetum hyemale) contains silica within its structure, making it an excellent natural scouring pad for cleaning pots and pans on the trail

plants in the Gila Riparian Preserve

One-seed Juniper, Prickly Pear Cactus and Sotol Agave (Dasylirion whelerii) growing on a soilless outcrop of rhyolite welded tuff

Prickly Pear Cactus

Mostly Prickly Pear Cactus, Mesquite, and One-seed Juniper survive on ancient river deposits

The plants of the Gila Riparian Preserve are equally as diverse, ranging from gigantic ancient, old-growth Freemont Cottonwood (Populus fremontii) and Arizona Sycamore (Platanus wrightii) towering over the flood plain, to the arid, ancient, elevated river terraces and upland hills with their sparse cover of Engelmann Prickly Pear (Opuntia engelmannii), Honey Mesquite (Prosopis glandulosa), and One-seed Juniper (Juniperus monosperma).

Gila River Gaging Station, New Mexico

Lunch at the USGS Gila River Gaging Station

With the exception of a short climb up and over a 100-foot-high ridge composed of ancient river outwash and flood plain deposits (encountered just after crossing Mogollon Creek), the first 2 miles of the trail is within the Gila Riparian Preserve and is very easy to hike and follow as it lies entirely along the Gila River floodplain, following an old road (closed to public vehicles) to the US Geological Survey Gaging Station on the Gila River. The gaging station is an interesting feature itself, having measured stream flow on the Upper Gila River on a daily basis since 19271. About 200 feet beyond the Gaging Station, the trail fords the river, whereby the Mogollon Box Trail soon enters lands of the Gila National Forest.

Trail along the Gila River

Rubber Rabbitbrush

Rubber Rabbitbrush (Ericameria nauseosa) and flood-deposited debris cover the floodplain

Arizona Sycamore

An old Arizona Sycamore soon to be taken by the river

Once the first ford is crossed, the Mogollon Box Trail can become much more challenging both physically and mentally depending upon the season of the year and effect of recent floods. Often, especially in late Summer or after Spring floods, the condition of the trail degrades from faint to non-existent as it follows the Gila River upstream along a narrow floodplain through a series of deeply-incised meanders within steep-walled canyons where heavy riverside vegetation brush may require the breaking of new trail, and steep, rocky cliffs to the water’s edge demand frequent fording of the river. While it is possible to hike from the Gaging Station upstream about three miles to access Turkey Creek Road (Grant County Rd. G2-24, FR 155) at Brushy Canyon or Brock Canyon, it must be stated that due caution must be taken if this portion of the trail is attempted. While beautiful as only the Gila River can be, this stretch of the river is essentially pure wilderness – isolated and rarely travelled. It is only doable at certain times of the year, depending on the height of the river, and is especially problematic during Spring runoff and the Summer monsoon season (end of June through mid-September) when flash floods are common. Local knowledge on existing conditions should always be solicited before undertaking this part of the trail.

Hiking trail along the Gila River

Heading home after a great hike


Directions to the Mogollon Box Trail

From the community of Gila take NM 211 towards the community of Cliff. Approximately one-half mile after passing over the Gila River bridge, turn right on Box Canyon Road (NM 293). Follow this road 5-1/2 miles to enter the Gila National Forest where the road becomes a county-maintained gravel road. After about 1 mile the road will drop down off an old river terrace to the modern Gila River floodplain. As soon as the road reaches the bottom of the slope, park on the left (GPS Coordinates N33° 02.665′, W108° 31.935′). Begin walking due north at this point along an old dirt path/4×4 roadway where, in about 100 feet, you will encounter a chained gate with an opening through the fence just to the right of the gate. This is the southern boundary of the Nature Conservancy’s Gila Riparian Preserve. Walk through the opening and continue, following the old roadway for about 2 miles to the USGS Gila River Gaging Station (GPS Coordinates N33° 03.691′, W108° 32.243′). The old roadway is the trail.

Directions to the US Forest Service Mogollon Box Recreation Area (at the beginning of the Mogollon Box Trail)

At the place where you park your car you are on Gila National Forest land. You will notice that at this point the road that you drove in on turns abruptly east and then south with a maze of numerous paths/primitive roadways leading off of it towards the river. The main road continues south for about 1/2 mile, providing access to the USFS Mogollon Box Recreation Area for walking, swimming, camping, and picnicing along the Gila River on Gila National Forest land. On a hot summer day it serves as the perfect local swimming hole. An outdoor toilet will be found along the southern access road.


1. Geomorphology of the Upper Gila River Within the State of New Mexico, Mussetter Engineering, Inc., June 2006


Posted in Gila National Forest, Gila River, hiking | Tagged , | 1 Comment

A GLORIOUS HIKE in the Middle Box of the Gila River to a 1,000-year-old Swimming Hole Carved in the Ash-Flow Tuffs of the Schoolhouse Mountain Caldera


Burro Mtn. Trailhead Sign

Billings Vista Bird Sanctuary & Trailhead for FT 746

Two week ago, two of our good friends from County Kerry, Ireland, spent a few days with us at Casitas de Gila Guesthouses while touring the American West. At the time, the lightening-caused Whitewater-Baldy fire had been burning for two weeks in the heart of the Gila Wilderness some 20 miles to the northwest of us. Since our guests were avid hikers, and the Forest Service had closed some of our usual hiking trails due to the fire, we decided it was a good opportunity to explore a different part of the Gila National Forest: the Burro Mountains.

The Gila National Forest is huge, offering some 1,500 miles of trails within its 3.3 million acres, and while we have spent a lot of time hiking and exploring the Gila country over the past 13 years, at best we have only scratched the surface, having a tendency to take our various visiting guests to the same favorite areas over and over again.

New Mexico's Burro Mountains in the Gila National Forest

New Mexico's Burro Mountains in the Gila National Forest

Lightening caused fires in the Gila Wilderness are a common occurrence, and during the 13 years that we have lived in Gila we have witnessed several such events. As with previous fires in the Wilderness, the Whitewater-Baldy fire was not affecting the Casitas in any way, either by smoke or other problems, since the Casitas are located south of and, due to prevailing winds, upwind from the Gila Wilderness and the fire. So with prevailing wind in mind, we decided that a good choice for our hike would be the Burro Mountains, about 9 miles south of the Casitas. Most of the Burro Mountains, about 250 square miles or 160,000 acres, lies within the Gila National Forest. It is an interesting and varied mountain range, steeped in history, that is transected by the Gila River at its northern end, and an area which we had only briefly visited a few times before.


Geologically, the Burro Mountains display a fascinating and extremely complex history of ancient sedimentary deposition; deep burial; deep seated, magmatic, pluton-forming activity; repeated uplift and erosion; accumulation of thick layers of welded tuff following explosive volcanic caldera eruptions; and extensive faulting, followed by late-stage mineral emplacement. It is a story in stone extending back over 1.5 billion years, where, today, many of the various chapters of this ancient history of the earth are exposed and laid open for all to see in the Middle Box by the eternal downward cutting action of the Gila River over many millions of years.

Silver City, New Mexico's Burro Mountains

Across the Floodplain and into the Woods!

The more recent history of the Middle Box of the Gila is equally as intriguing. In pre-historic times, the entire length of the Gila River was a major thoroughfare for east-west travel, and was considered home to countless generations of early Native Americans such as the Mogollon Culture who hunted, fished, farmed, camped, and built villages both small and large along its course from about 150 to 1400. For the interested and observant hiker, remnant signs of these early cultures can be found in numerous places along the Gila River.

A hundred years or more after the Mogollon peoples left, the Apaches arrived and claimed this dependable desert oasis of the Gila River as home. In the years to come the Burro Mountains were at the center of much of the Apache Wars with the incoming wave of pioneer miners, ranchers, and farmers from the East. During this chaotic period, all the Apache chiefs—Cochise, Mangas Coloradas, Nana, Victorio, Chihuahua, and Geronimo—knew the Middle Box of the Gila River intimately.

Cottonwood trees in Burro Mountains

In the Hall of the Cottonwoods

With the gradual taming of the West, it was inevitable that the ubiquitous and intrepid group of men known as prospectors would find their way into the Burro Mountains. And, much to their great joy and delight, here they found silver and yellow metals in great abundance. Beginning in the 1880s, and fully established by the early 1900s, several mining districts were recognized at various places within the Burro Mountain chain. Scattered throughout these rugged mountains and canyons numerous small prospects and mines were developed, yielding significant amounts of gold, silver, copper, turquoise, and fluorite1,2. Within a few decades, however, all but a few of these small mining operations had been worked out and had ceased production. But, then, just as the small mines began to close, intensive mineral exploration projects were undertaken in the southern Burro Mountains which eventually delineated the presence of extensive and massive deposits of low-grade copper ore which could be extracted at a profit, if done on a large scale. Thus was born a new phase of mining in the Burro Mountains. It is one that continues today in the form of the mega-scale operation of Freeport-McMoRan Copper and Gold Corporation’s Tyrone Mine, located in the southern Burro Mountains, about 15 miles south of Silver City. The Tyrone Mine is a huge open pit and processing facility which in 2010 produced 37.19 thousand tons of copper3.

In the northern Burros, however, most of the old mines, prospects, and workings ceased operations long ago and are now mostly forgotten and inaccessible, scattered throughout a rugged and roadless terrain.


Gila National Forest Hiking Trail

Off We Go!

And so it, was with a sense of heightened anticipation on my part for a trail never travelled, that our two guests, two neighbor friends, two dogs, and myself set off for a day hiking and exploring Forest Trail 746 in the Middle Box of the Gila River.

In New Mexico, the term “box” is used to describe the narrow canyons along the course of a river or creek, which can serve as a handy place for ranchers to drive and corral or “box” up their wide-ranging cattle. In the case of the Middle Box, it refers to the narrow canyon cut by the Gila River as it transects the north-south trending Burro Mountain Range between the Upper Box at the edge of the Gila Wilderness upstream and the Lower Box of the Gila near the Arizona border downstream.

Swimming Hole in Gila River near Silver City, NM

The Swimming Hole of the Ancients

Forest Trail 746 is a well-marked trail which leads downstream, deep into the high-walled canyon narrows of the Middle Box of the Gila River. Recently the trail has been upgraded for at least the first two miles. Substantial rock cairns mark the way across the wider stretches of sand and gravel floodplain that are devoid of vegetation, and the trail has been cleared as it goes through the dense stands of young cottonwood, willow, and shrubby vegetation that border the river channel. The trail follows the east side of the river for the first 0.7 mile, and then crosses to the west side of the river for the remaining 1.3 miles to the destination and end point of this trail discussion, the Swimming Hole of the Ancients.

Prickly Poppies in New Mexico

The Prickly Poppy (Argemone pleiacantha) abounds along FT 746

Trail 746 is a trail that can be enjoyed by people of every age and ability. The first two miles the trail are mostly across level floodplain with only a few gentle grades. The trail meanders back and forth, towards and away from the river, first across sunlit expanses of river sand and gravel, and then beneath shady canopies of thick stands of young, 80- to 100-foot-tall Fremont Cottonwoods (Populus fremontii) that germinated along the natural levees of former floodplain channels.

In many ways, FT 746 is a passage of riverine solitude for the senses and one’s soul, offering an unforgettable, tranquil, and calming journey into the subtle essence of Gila River country. The weather on the day of our excursion was typical for the first week of June: sunny and in the mid-80s with clear blue skies and a nice breeze out of the south blowing upstream. At this late-spring time of the year, the floodplain vegetation along the river was already in full summer dress, a ribbon of green having diverse fragrant smells, and many flowers, such as Prickly Poppy (Argemone pleiacantha), lining the trail. Although the Spring bird migration had peaked a few weeks earlier, the varied calls of numerous transient species could be heard frequently, rising melodically over the ceaseless background murmur of the cottonwood leaves rustling in the canopy high above. Indeed, it was a glorious morning, and we were all reveling in it, including Red and Bower, our two canine companions.

Gila River in Burro Mtns in New Mexico

Huge, old cottonwood washed out at river crossing

FT 746 begins by first crossing a dissected outwash plain of sand, gravel and boulders washed out from Ira Canyon to the east. It then rises briefly to cross a stretch of older river terrace of sand and gravel, densely covered with Honey Mesquite (Prosopis glandulosa) and a few One-seeded Juniper (Juniperus monosperma), before dropping down to the upper part of a broad modern floodplain sparsely covered with Rubber Rabbitbrush (Ericameria nauseosa), Seepwillow (Baccaris salicifolia) and the occasional old-growth cottonwood. After 0.2 mile, the floodplain narrows and the trail passes into a dense stand of mature cottonwood and willow which continues for another 0.2 miles. After passing through a particularly dense stand of trees, the trail then emerges abruptly at a broad, shallow river crossing. The crossing point is well marked by the remains of a huge, old growth cottonwood that toppled into creek in recent years when the river bank was undercut during a period of flooding and the eastward lateral migration of the main channel. As typical for this time of year, the flow of the Gila was low, only about calf-deep, when we made the crossing. The Spring runoff, minimal as it was this year because of a second-year-in-a-row dry La Niña Winter, had peaked several weeks earlier.

Burro Mountains in Gila National Forest New Mexico

Once the river was crossed, the trail again entered into a zone of alternating stretches of floodplain sand and gravels, and dense, high-vaulted stands of young cottonwood and willow, with an understory of waist-high, thick-growth young willow trees.

The contrast in sensual perception between the alternating sunlit, barren sand and gravel, and shaded, lush vegetated tunnels of plant growth was intense and inescapable as we hiked the next half mile of the trail. Leaving the floodplain, we followed the trail as it climbed up onto the bordering mesquite and juniper covered terrace, and then abruptly emerged at the top of a 15- to 20-foot-high, white rocky promontory jutting out into the river. We had arrived at our lunch time destination, the Swimming Hole of the Ancients!

Burro Mountains Gila National Forest New Mexico

Our lunch spot, overlooking the Gila River

And what an idyllic and magical spot it is! Within less than a minute, our canine buddies were frolicking in the river, swimming, and chasing sticks, while their owners and friends relaxed at the promontory’s edge and examined the intriguing grinding holes made a thousand or more years ago by the ancient tribes that passed this way. There could be no doubt that the ancients considered this place as special as we did. The 4 to 6 inch depth of the several holes at the top of the rock promontory where they ground their maize and other food stuffs offer mute testimony that countless generations of ancient travelers had paused here to swim, rest, and eat before or after passing through the rugged, narrow, rocky chasm of the heart of the Middle Box that our map indicated was just another half mile or so downstream.

Mimbreno grinding hole in Burro Mtns in New Mexico

Where the Ancients ground their maize

This rocky promontory is the first outcrop of bedrock to be found within the river as one hikes downstream towards the narrows of the Middle Box, a telltale sign of the chasm ahead. The ancients, of course, knew this, and also knew that this rock was excellent for grinding grain, although they didn’t know why. It would be a thousand years or more before geologists would come to understand the why, that this abrasive rock is a rhyolite ash flow welded tuff, deposited there some 33.5 million years ago in the Late Oligocene Epoch during an eruption of the Schoolhouse Mountain Caldera, about 3 miles to the east (Ref. 1).

Gila National Forest New Mexico

Time for Lunch!

Sitting there quietly munching a sandwich and observing our surroundings as the afternoon breeze rushed upstream through the leaves of the thick stands of willow and cottonwood lining the banks, it was not at all surprising when the vision of how it must have been began to play in one’s mind … a scene of young children playing, swimming, and jumping from the promontory into the river below, under the ever-watchful eyes of their mothers grinding the corn on the rocky promontory above, while the older men scoured the mesquite thickets on the hillside behind for a nice plump rabbit to round out the meal.

And then, all too soon the scene faded, and we knew it was time to pack up and head back.



Sign for FT 746

Trailhead Sign for FT 746 in the Burro Mountains

To reach the trailhead for Forest Trail 746 from Casitas de Gila Guesthouses, take NM 211 south from the Gila Post Office for 4 miles to US 180; turn right (west), and in 1 mile turn left on Bill Evans Lake Road. At 3.4 miles the road forks, with the road to the left leading away from the river to Bill Evans Lake. At this fork stay straight ahead for 1.9 miles to enter the Gila National Forest. After going another 4.5 miles the road leads to a designated and marked birding area with access to the Gila River. At this point continue driving south, parallel to the river, on a less travelled dirt road to dead end at the Billings Vista Birding Area and the trailhead for Forest Trail 746.


  1. 2005, Virginia T. McLemore, Mineral Resources of the Wild Horse Mesa Area, Northeastern Burro Mountains, Grant County, Open-file Report 486.
  2. 1964, Elliot Gillerman, Mineral Deposits of Western Grant County, New Mexico, New Mexico Bureau of Mines and Mineral Resources, Bulletin 83.
  3. Mining Almanac


Posted in Burro Mountains, geology, Gila National Forest, Gila River, hiking | Tagged , , , , , | 4 Comments

Becky & Michael O'Connor, Owners
50 Casita Flats Rd • PO Box 325 • Gila, New Mexico 88038



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