AN EXCEPTIONAL SNOWFALL
THAT TRANSFORMED CASITAS DE GILA GUESTHOUSES
INTO A WINTER WONDERLAND
Turtle Rock rises above Bear Creek with the Gila Wilderness in the background after the Great Snow of January 2, 2015
WINTER CLIMATE IN THE SOUTHWEST:
CONTROLLING FACTORS, AVERAGES, AND EXCEPTIONS
The average Winter snowfall received at Casitas de Gila Guesthouses and Southwest New Mexico is a function of several factors, including:
- the large scale alternating weather pattern in the Pacific Ocean known as the El Niño Southern Oscillation (ENSO), which results in the periodic warming and cooling of sea surface temperatures across the Pacific within the tropics and subtropics, and the creation of the important climatic patterns commonly referred to as El Niño (warm) and La Niña (cool) episodes
- large-scale Jet Stream patterns over western North America
- prevailing local atmospheric pressure and temperature
- local elevation
Climatic Affects of El Niño and La Niña Winters on New Mexico
Historical records show that El Niño winters in the Southwest are marked by increased precipitation and warmer temperatures, and La Niña winters by decreased precipitation and colder temperatures. During El Niño years, moisture-laden Low Pressure systems coming in off the Pacific Ocean tend to follow a southern route, carried along by the west-to-east flow of a persistent Pacific Jet Stream across the Southwest and into southern New Mexico (see figure below.) During La Niña years, however, eastward-moving, moisture-laden Low Pressure systems coming in off the Pacific Ocean tend to take more northerly routes across the western U.S., carried along by the west-to-east variable flows of the Pacific and Polar Jet Streams, bringing dry, sunny High Pressure conditions to prevail over the Southwest and New Mexico.
Schematic drawing showing climatic weather patterns of El Niño and La Niña for North America. Prepared by NOAA/ National Weather Service/ National Centers for Environmental Prediction.
Monitoring Oscillations of El Niño and La Niña by the Oceanic Niño Index
Sea surface temperatures fluctuate constantly in the Central Pacific along the equator, and when monitored and averaged over time demonstrate repeated oscillations between El Niño (warm) and La Niña (cold) episodes. The U.S. National Oceanic and Atmospheric Administration (NOAA) monitors these oscillations by averaging monthly measurements of surface sea water temperatures collected over an area that covers the central portion of the Pacific Ocean between 5°N and 5°S latitude and 120° to170° W longitude. These temperature fluctuations, when averaged over successive three-month intervals during the year (which NOAA refers to as “seasons”), yield temperature anomalies that NOAA calls the Oceanic Niño Index (ONI). ONI values generally lie within 3°C of the average temperature for any given area at any specific time of the year. Anomalies that deviate from the average temperature in excess of +0.5°C mark a shift towards a warm El Niño episode, whereas anomalies in excess of -0.5°C mark a shift towards a cold La Niña episode. Anomalies that are between ±0.5°C are called a Neutral Episode, or, as they are sometimes humorously referred to, a La Nada episode. By NOAA’s definition, an El Niño or La Niña Episode can only be so named when the average of three consecutive ONI three-month seasonal values exceed the ±0.5°C threshold.
The Oceanic Niño Index has been in a Neutral or La Nada episode since the March-April-May seasonal ONI of 2012, and current projections (.pdf file) as of January 19, 2015 are that of a 50-60% chance of weak El Niño conditions during February and March, with a ENSO Neutral episode thereafter.
PREVAILING CLIMATIC CONDITIONS THAT SET UP
THE GREAT SNOW OF JANUARY 2, 2015
Typically, winter snowfall at the Casitas for the past 16 years has consisted of two or three light snowfalls each year, with each amounting to two or three inches or less. Generally, these snowfalls occur in the following predicable pattern: As low pressure systems come in from the west, winds are out of the southeast bringing warm air up from Mexico, which causes the precipitation to start as rain. Then, as the low pressure system passes by heading east, the precipitation may turn to snow overnight as the winds shift to the north. Once the storm has passed by, the skies clear, and the brilliant New Mexico Sun returns, the snow melts off quickly, typically during the following day.
Casitas de Gila is situated at an elevation of 4,800 feet. Small differences of elevation on the order of just a few hundred feet can result in a change in precipitation falling as rain or snow. For example, it is not uncommon during a Winter precipitation event at the Casitas for the 5,500 foot summits of North and South peaks (they rise up directly east of the Casitas on the other side of Bear Creek) to be coated with snow, while the Casitas receive nothing but rain. As another example, Silver City, which lies at an elevation of 6,000 feet, gets at least twice as much snow as the Casitas during the Winter.
The Great Snow of January 2, 2015, however, did not follow this usual pattern at all, but instead resulted from an unusual set of climatic factors: 1) A La Nada to very weak El Niño pattern had prevailed during the last weeks of 2014, and 2) Jet Stream patterns in the western U.S. were complex, not resembling either of the simple patterns shown in Figure 1. Instead, the Jet Stream patterns were repeatedly developing into very unusual, complex loops that came south down along the west coast of the U.S. from Canada, bringing masses of cold arctic air to the Southwest before angling northeast to bring rain to East Coast. By January 1, the Jet Stream had split, developing a pattern more like the El Niño pattern shown in Figure 1, with a Northern Polar Jet Stream and a southern Pacific Jet Stream which was now bringing up warm, moist air from Baja California. With cold air still lingering in the upper atmosphere from the previous loop pattern and the subsequent influx of moist air from the south, the stage was now set for the Great Snow of January 2, 2015. On that day it snowed all day, dropping a total of between 7 and 8 inches and turning Casitas de Gila into a Winter Wonderland. While old timers of the Gila area said they could remember greater snowfalls in the past, younger locals could not, and for certain it was the greatest snowfall the Casitas had experienced in 16 years of operation. Even so, by noon the following day with the combined efforts of El Sol and the trusty Casita tractor, all roads were passable, permitting both departing guests to leave and arriving guests to arrive.
A WINTER WONDERLAND AT CASITAS DE GILA GUESTHOUSES
The snowfall began in the early morning hours of January 2 with a couple inches of light dry snow on the ground by 8 AM. Despite a few brief periods when it appeared that the snow would soon stop, in never did until late in the afternoon when, as darkness approached, the skies finally began to clear.
Chloe wondering what has happened to her world, while Bower wonders what has happened to Turtle Rock.
Snow covered young Soaptree Yucca recently visited by a Desert Cottontail Rabbit looking for breakfast of grass, not yucca.
Bobcat looking for breakfast of Cottontail Rabbit.
Cane Cholla Cactus decked out with snow.
With dawn, the habitual early morning walk past the Casitas and down along Bear Creek to the horse corral revealed a true Winter Wonderland. On the flat to the west of the Casitas, Mule Deer (Odocoileus hemionus) and Desert Cottontail Rabbit (Sylvilagus auduboni) tracks criss-crossed the snow-covered road. Here and there Bobcat tracks followed the rabbit tracks, although evidence of an actual encounter was not found. Our two English Springer Spaniels were very excited by it all, sniffing, frolicking, rolling, and chasing one another all the way to the corral and back. The One-seed Juniper (Juniperus monosperma), Soaptree Yucca (Yucca elata), and Cane Cholla Cactus (Cylindropuntia spinosior) were all resplendent in their new, thick blanket of white, the juniper branches sagging under the unaccustomed weight. For most of the guests, it was a great day for hunkering down inside their Casita, enjoying the cheer of hot chocolate and a good book by their kiva fireplace; but by the afternoon the incredible natural beauty steadily enveloping the Casitas was too much to ignore, prompting several photographic pilgrimages down to the Creek.
As the Great Snow day continued, not a creature was stirring, not even a guest (except those inside by their kiva fireplace).
Full moon rising over North Peak across from the Casitas
With the low pressure system now past and heading east, the night of January 2 came on cold and clear. Slowly, the near-full moon rose above North and South peaks, casting the snowscape in the mystic bluish light and dark shadow that can only be experienced following a fresh heavy snowfall. Magical!
Heading down to Bear Creek on the Corral Road before dawn the day after the Great Snow.
The Casitas, Turtle Rock and the distant Gila Wilderness the morning after the Great Snow.
On the trail down to Bear Creek, with Turtle Rock and the Gila Wilderness in the Distance.
A young sycamore steps from the forest shadows, its rusty-red leaves ablaze in the morning Sun.
Cottonwoods and Willows frosted with snow.
With the next morning’s light, the dogs found the trip to the Creek even more exciting, the deeper snow coming up to their bellies. It seemed, however, that most of Nature’s furry friends were still sleeping in, as only a few deer and rabbit tracks were found crossing the road by the Creek. As expected, when dawn broke and the first rays of El Sol emerged from behind North and South peaks, the landscape surrounding the Casitas was immersed in endless waves of brilliant light. A trip along the Creek was a must to document this rare natural spectacle before it melted away.
Traveling upstream from the Casitas’s southern boundary, it was hard to progress more than a few yards before yet another photo opportunity would present itself. Bear Creek gurgled sharply in the morning silence. The maze of cottonwoods and willows lining the creek glistened yellow-white in the morning light, with every snow-frosted branch and twig etched in sharp contrast against the cerulean sky, while deep shadows of cobalt blue criss-crossed at their feet. Here and there the maze of yellow-white and blue would suddenly be broken, as a lone sycamore would burst into view, its rusty-red leaves ablaze in the light.
The waters and even the margins of Bear Creek rarely freeze because of constant vertical circulation and mixing of warmer waters rising, and colder waters sinking, within the thick layers of loose sand and gravel sediment of Bear Creek.
Cycles of Nature abound in the quiet, shallow margins of Bear Creek. Here, Duckweed and Watercress encroach on a fallen sycamore leaf and willow leaves.
Along the margins of the Creek, narrow bands of wet, reddish-brown sand and gravel marked the edge of the warm, upwelling spring-fed waters. For most of its course past the Casitas, the waters of Bear Creek rarely freeze in the Winter because of the vertical circulation and mixing of warmer waters rising and colder waters sinking within the thick deposits of loose sand and gravel sediment that make up the stream bed of Bear Creek. Through this upwelling circulation the waters are warm enough in places that occasional patches of bright Springtime-green Watercress (Nasturtium officinale) and Pale Duckweed were encountered, flourishing in defiant counterpoint to the surrounding Mid-Winter snowscape.
Continuing further up the creek, immersed in the cold shadows of the towering cliffs above, one soon came to a higher-energy, rocky portion of the creek where, during the Great Bear Creek Flash Flood of last Fall, concentrations of large pebbles, cobbles, and boulders were deposited in thick gravel bar deposits along the margins of the Creek, while the finer sediments were swept away. Here in this cliff-shadowed segment of the Creek, there were no signs of the warm, upwelling spring-fed waters just observed a short distance downstream. Instead, the stream bank remained frozen solid to the water’s edge, and where former gravel bars were once observed, the Creek margin was now transformed into a lumpy expanse of stoney-cored, oversized marshmallows glistening in the morning Sun.
Stoney-cored marshmallows emerge from the deep shadow of the cliffs to glisten in the morning Sun.
The telltale track of the White-nosed Coatimundi (Nasua narica).
Tracks of animals, some fresh, some old, were abundant in most places along the Creek – Mule Deer coming to drink and feed on the Watercress and Duckweed, Rocky Mountain Big Horn Sheep coming down off the cliffs to the water, the five-toed, telltale track of the elusive White-nosed Coatimundi (Nasua narica), small tracks of Mice (Family: Cricetidae) and larger tracks of the Gray Fox (Urocyon cineroargenteus) hunting the mice; but on this day, no sign of Mr. or Mrs. Mountain Lion (Puma concolor).
Female Ruby-Crowned Kinglet hunting for insects on the Watercress and Duckweed-lined pool.
Black Phoebe hunting for insects at the pool.
As the morning wore on and the snow began to fall from the trees, creating a little plop here and a little kerplop there, a variety of birds including the Wood Thrush, the Ruby-Crowned Kinglet, and the Black Phoebe were found feeding on insects near a large pool of water situated in the middle of the floodplain, a short distance east of the main Creek Channel. The pool, which has persisted at this particular location for several years now, is elongated in shape, measuring up to several feet across and a couple of hundred feet long, with water depths ranging from a few inches to up to a foot. Interestingly, the water level in the pool is elevated a foot or two above the level of the main channel of the Creek into which it drains.
Red-naped Sapsucker hunting for insects on an old juniper.
Observations made over the years reveal that this pool is formed by confined subsurface creek waters that rise to the surface of the floodplain at this spot from an abandoned main creek channel that was buried with fine silt and mud when the creek changed its course during the Great Flood of 2005. Because the pool is fed by warm water rising to the surface of the floodplain, Watercress and Duckweed flourish on the pool’s surface year around, which seems to be a delicacy for the Mule Deer in the winter, judging by the abundance of tracks at the water’s edge. Peering into the water, small minnows could be seen cruising up and down the length of the pool continuously, only to instantly disappear and hide beneath the floating Watercress and Duckweed whenever danger was sensed in the shadows cast from above. A variety of small insects also abound here year around, in the water, along the margins of the pool, and incredibly and to the obvious delight of the Black Phoebe on this sunny warming day, even flying just above the surface of the water. Observing this smorgasbord of Nature’s bounty it was as if one had suddenly time-travelled from a Mid-winter Snowscape into Early Spring.
By noon the melting of the snow was in full display, with snow dropping noisily from the branches of the large oaks and junipers bordering the floodplain. Having just started the short hike back to the Casitas, a bird flew close overhead to land on the trunk of a tall juniper about 60 feet distant and instantly began pecking away. At that distance, it appeared to be a Ladder-Back Woodpecker and remained there fully engaged in its foraging for about a minute, quite long enough to permit several telephoto pictures. Looking at the photos back in the studio, it was quickly obvious that the bird was not a Ladder-back, but rather a new bird that had never been reported at the Casitas. It was a Red-naped Sapsucker! What a colorful and handsome bird they are. And, what a marvelous hike it had been!
Leaving Bear Creek at noon, the snow was melting fast, and within a short time the Great Snow of January 2015 would be but a memory.
CENTERPIECE OF A MAGNIFICENT LANDSCAPE
IN SOUTHWEST NEW MEXICO
Sacred Site of the Mogollon People, Craggy Stronghold for the Apache, Landmark for the Pioneers, Gateway to Bear Creek, and Nature’s Monument to Beauty
Rising majestically above Bear Creek, Turtle Rock is the centerpiece of this Mid-Winter scene.
TURTLE ROCK: NATURE’S GIFT DOWN THROUGH THE AGES
We do not know what the Mogollon People called the towering mass of cliffs rising majestically from the creek across from their village. Yet, most likely, they were spiritually moved by it as they emerged from their cluster of pit-houses in the predawn hours, watching as the first rays of the Sun burst once more over its summit to start the new day, or stood waiting for the luminous orb of the full moon to slowly rise over the shadowed mass of rock to illuminate their sacred evening dance. The Apaches treasured this special place along the creek as well, both as a reliable hunting ground for game, especially the Bighorn Sheep that favored its craggy cliffs, and, because of the gently sloping flat top of the fortress-like cliffs, as a safe haven for their old, young, and infirm, as well as their appropriated horses and cattle, while the warriors were off on another of their recurring raids.
Glistening in the last rays of a Late Summer Sun, Turtle Rock has served as a visual magnet of inspiration since the days of the Mogollon People.
By the late 1800s, pioneer ranchers and settlers moving into the lush Gila Valley had various names for this prominent rocky landmark that was visible for miles around and which served as a guidepost for the entrance to Bear Creek, the shortest and best route of travel to the growing towns of Pinos Altos and Silver City. For some it was known as the Apache Corral; for others it was Bill Hooker’s Hill, marking the location of the headquarters for the expansive pioneer Hooker Ranch now nestled in the shadow of its cliffs. By the early 1950s, however, the lyrics of a new song inspired a more poetic name, that of Mockingbird Hill, which had become a hit tune throughout the U.S., made famous by Patti Page and several others.
Today, another name has been added to the lexicon with the imposing craggy butte now commonly referred to as Turtle Rock because of its turtleback-shaped profile.
Situated on the edge of Bear Creek and overlooking the incomparable Gila Wilderness a few miles distant to the north, Turtle Rock continues its long history of human attention as a much admired and photographed centerpiece of the marvelous landscape viewed from Casitas de Gila Guesthouses.
BORN OF FIRE, AND SHAPED BY THE AGES
Looking north at Turtle Rock from the Paradise Overlook Trail at Casitas de Gila towards the Gila Wilderness in the Pinos Altos Range (on right) and the Mogollon Mountains (on left), with Mogollon Baldy Peak (10,770 feet) on far left skyline. Note the horizontal bedding in the layers of welded tuff and pyroclastic breccias on the vertical cliffs.
The origins of Turtle Rock can be traced back some 28 million years ago to the Oligocene Epoch (note: link is a .pdf file), when the Bursum Caldera was erupting violently some 20 miles to the northwest, in the center of what is now the Gila Wilderness. Numerous eruptions within the caldera resulted in the deposition of thick sequences of pyroclastic volcanic material over the surrounding area, ranging from fine-grained welded tuffs to coarse-grained pyroclastic breccias.
Turtle Rock consists of layers of both welded tuff and pyroclastic breccias, which are composed of angular fragments of rhyolite and andesite set in a fine-grained matrix of welded tuff. Millions of years after the deposition of these volcanic rocks, tectonic faulting and uplift took place over the area during the Miocene Epoch (note: link is a .pdf file). This tectonic uplift resulted in the formation of the Silver City Range, a 19-mile-long mountain range extending northwest from Silver City to terminate at Turtle Rock on the east side of Bear Creek. Here, vertical movement along a major north-south trending high angle normal fault during this time period resulted in the uplift of the west facing craggy cliffs of Turtle Rock and the adjacent steep slopes of North and South Peak to the south. Following the uplift of Turtle Rock and North and South Peaks, millions of years of weathering and erosion then took place, ultimately resulting in the magnificent landscape as seen today across from Casitas de Gila Guesthouses.
Closeup of pyroclastic breccias found on Turtle Rock. Note horizontal bedding and angular fragments in the welded tuff matrix.
Looking north at eastern side of Turtle Rock with Gila Wilderness in the Pinos Altos Range (to right) and the Mogollon Mountain Range (to left) in background.
THE MANY MOODS OF TURTLE ROCK
During the Summer Monsoon season, guests at Casitas de Gila are frequently treated to the spectacular sight of rainbows over Turtle Rock.
The craggy cliffs of Turtle Rock rise up as the dominant focal point within the vast mountainous landscape bordering Bear Creek, but nowhere as much so as when viewed from the edge of Bear Creek Canyon in front of Casitas de Gila. Looking north from anywhere on Casita lands, the commanding presence of Turtle Rock sets the mood and tone of the day, regardless of the time of year or weather. Indeed, after 16 years of living here, it is a rare day that one does not spend at least a few minutes marveling at this enduring gift of Nature’s beauty, exquisitely situated against the soaring mountainous peaks of the Gila Wilderness rising up a few miles to the north in the distance. Without question Turtle Rock is a southwestern landmark that will delight any Nature lover, photographer, or artist that has the opportunity to visit.
Turtle Rock as seen from the Corral Road trail following an unusual Winter snowfall.
Turtle Rock as seen from the Corral Road during Summer with the hills covered with Summer Poppies.
Clouds rising behind Turtle Rock in the late afternoon create ever-changing, majestic landscapes in front of the Casitas.
While it is very true that a picture is worth a thousand words, in the case of Turtle Rock it is also true that a photograph rarely captures that innermost deep feeling that moves one to pick up the camera in the first place. Nevertheless one keeps trying.
The following photos have been selected from literally several thousand taken over the past 16 years in an ongoing attempt to record the incredible beauty and changes of mood of the unique and very special landscape of Turtle Rock and its surroundings that continue to greet one’s eye and inspire one’s Spirit day after day, month after month, year after year.
TURTLE ROCK IN WINTER
Looking north from the Casitas at Turtle Rock in early morning light after a rare fresh snowfall.
A typical Winter scene from the Casitas of a half-shadowed Turtle Rock overlooking a forest of brilliant white-barked cottonwoods and occasional red-leafed sycamores lining Bear Creek with the cloud-shrouded peaks of the Pinos Altos Mountains in the Gila Wilderness in the distance.
Turtle Rock cloaked in a rare pre-dawn fog in Mid Winter.
TURTLE ROCK IN SPRING
In Early Spring the cliffs of Turtle Rock take on a warmer shade of tan as the buds in the cottonwoods lining Bear Creek take on a hint of yellow-green, while a rainbow forms over the Gila Wilderness.
By Late Spring, Turtle Rocks takes on an even warmer tone as the Sun soars ever higher in the sky and the Bear Creek riverine forest puts on its brightest show of yellow-green.
TURTLE ROCK IN SUMMER
Often during the Summer Monsoon season a break in the clouds following a late afternoon thunderstorm will create a moment of pure magic.
With the Summer rain, Turtle Rock turns into a green-backed turtle!
As the Summer afternoon Sun slowly sets in the West, Turtle Rock will change from yellow, to orange, and then to red just for an instant before … lights out!
And then, just when one thinks one has seen it all … the Magic of Turtle Rock will put on a display that simply leaves one breathless.
TURTLE ROCK IN FALL
As Fall comes on, the Sun arcs lower in the sky and the days and nights begin to cool and Turtle Rock takes on a more somber tone, reflecting the deeper shade of blue in the skies above and the turning of the cottonwood leaves along Bear Creek.
As the days shorten, shadows lengthen and the colors of the turning leaves are set in exquisite tonal harmony against the soaring cliffs of Turtle Rock.
In the morning light, Turtle Rock is in shadow, providing the perfect counterpoint of contrast to the peaking of the cottonwood leaves ablaze along Bear Creek.
Once the leaves peak along the Creek and start to fade and fall, the towering shadowed cliffs of Turtle Rock will remain as an essential focal point of contrast in this gorgeous scene until the last of the color is gone and the more somber tones of Winter once more return.
HIKING IN THE FOOTSTEPS OF THE ANCIENT ONES
IN THE MOGOLLON MOUNTAINS OF THE GILA WILDERNESS
A Thanksgiving Holiday Hike Up Sacaton Creek
in the Mogollon Mountains of Southwest New Mexico
Looking north at the western escarpment of the Mogollon Mountains
THE MOGOLLON MOUNTAINS: ANCIENT LAND BORN OF FIRE
Just a few miles north of Casitas de Gila Guesthouses, the majestic Mogollon Mountains rise over 6,000 feet in elevation from the Gila River Valley to form an imposing 30-mile-long escarpment between the communities of Gila and Glenwood. The Mogollons are the highest mountains in Southwestern New Mexico with several peaks just under 11,000 feet: Whitewater Baldy at 10,895 feet and Mogollon Baldy at 10,770 feet. Most of the Mogollon Mountains lie within the vast 557,873 acres of the Gila Wilderness that cover some 872 square miles and offer hundreds of miles of hiking trails (US Forest Service map; .pdf file).
Sacaton Mountain center horizon. Elevation 10,600 feet. Headwaters of Sacaton Creek. Like most of the Gila Wilderness, Sacaton Mountain and Sacaton Creek are composed of volcanic rocks deposited during the eruption of the Bursum Caldera 28 million years ago.
Geologically, the Mogollon Mountains lie in the southern part of what is known as the Datil-Mogollon Volcanic Field, a huge 10,000 square mile area at the southeastern corner of the Colorado Plateau Province consisting of numerous volcanic calderas that erupted during the development of the Basin and Range Province during the Late Tertiary Period (Paleogene and Neogene Periods). Almost all of the volcanic rocks comprising the Mogollon Mountains were formed during the Oligocene and Miocene Epochs, the largest volume resulting from the eruption of the Bursum Caldera, 28 million years ago. Following the eruption of the Bursum Caldera, extensive faulting and uplift occurred within the Mogollons between 20 and 15 million years ago resulting in the mountainous terrain that is seen today. It was also during this time period that the collapse of the Bursum Caldera took place, with the development of ring faults around the subsiding caldera periphery within which subsequent emplacement of veins of metallic minerals took place. It is these veins that would eventually yield the greatly-sought-after mineral deposits of gold, silver, copper, and fluorite that were actively mined in the Mogollons beginning around 1870.
The Mogollon Mountains, ancestral homeland of the Mogollon Culture. Gila River Valley in foreground at 4500 feet rising to 10,895 feet at the summit of Whitewater Baldy on the far distant skyline.
THE MOGOLLON MOUNTAINS: ANCESTRAL HOME OF THE MOGOLLON CULTURE
The Mogollon Mountains have been a magnet for Native Americans for several thousand years, beginning with the nomadic gatherer, hunter, and eventually incipient agrarian Archaic Cochise Culture. The primary reason for this draw is because of the extreme diversity of landscape, wildlife, and plant life that is found there. Starting at the Gila River Bridge, at an elevation of 4,500 feet, it is only 25 miles north to the crest of the Mogollons at Mogollon Baldy at 10,895 feet. In that short distance the landscape passes through five ecologic zones:
Soaptree Yucca (Yucca elata) and Honey Mesquite (Prosopis glandulosa) are characteristic plants of the Chihuahuan High Desert Zone. This photo is at Casitas de Gila, at an elevation of 4,800 feet.
High Chichuahan Desert Zone: 4,500-5,000 feet. Characterized by Honey Mesquite, Wait-A-Minute Bush, Soaptree Yucca, and Cacti. Average precipitation between 10 and 15 inches.
Alligator Juniper (Juniperus deppeana), Pinyon (Pinus edulis) and Gray Oak (Quercus grisea) are characteristic trees of the Juniper and Pinyon Zone. This photo is on Sacaton Mesa at an elevation of 6,100 feet. The building is the ruins of a 100 year-old adobe that may have served as a stage stop on the Old Sacaton Road. Sacaton Mountain (10,600 feet) center skyline.
Juniper and Pinyon Zone: 5,000-6,500 feet. Characterized by a slow-growing and drought-resistant “dwarf forest” of One-seed Juniper, Alligator Juniper, Pinyon, Gray Oak, and Desert Scrub Oak, plus Sotol, Prickly Pear Cactus, and Agaves. Average precipitation between 15 and 20 inches.
Ponderosa Pine (Pinus scopulorum) and Gambel Oak (Quercus gambelii) are characteristic of the Pine and Oak Zone. In this photo hikers pass beneath a forest of towering Ponderosas on Lower Sacaton Creek at an elevation of 6,700 feet.
Pine and Oak Zone: 6,500 to 8,000 feet. Characterized as the lowest biome of true forest consisting of Ponderosa Pine and Gambel’s Oak, plus numerous shrubs and weeds from lower and higher elevations. Average precipitation between 20 and 25 inches.
Douglas Fir (Pseudotsuga menziesii) and Quaking Aspen (Populus tremuloides) are characteristic of the Fir and Aspen Zone. Photo is looking east along Bursum Road at an elevation of 9,100 feet.
Fir and Aspen Zone: 8,000 to 9,500 feet. Characterized by extensive growth of dark-green Douglas Fir and white-barked Quaking Aspen, plus numerous shrubs and weeds from lower and higher elevations. Average precipitation 25 to 30 inches.
Englemann Spruce (Picea engelmannii) and Firs such as the White Fir (Abies concolor) are characteristic of the Spruce and Fir Zone. Photo of top of Mogollon Mountain at 10,600 feet.
Spruce and Fir Zone: 9,500 feet – 11,000 feet. Various species of spruce and fir trees are the dominant trees with dense stands growing up to tree line and commonly interspersed with alpine meadows. Numerous other high-altitude shrubs, grasses, and weeds not found at lower elevations occur here. Average precipitation ranges from 30 to as much as 90 inches, with north-slope snow drifts lasting into June.
Thus, within this relatively small geographic area Native American cultures had access to an extremely diverse variety of food sources including an incredible number of edible plants and fruits, small and large game animals, birds, fish, and eventually, as the indigenous cultures evolved, bottom land suitable for agriculture along the Gila River and its tributaries, such as Bear Creek. In short, for pre-Columbian Native Americans, the Mogollon Mountains and the adjacent lowlands were truly a Garden of Eden. And they remain so today.
THE PRE-COLUMBIAN NATIVE AMERICAN MOGOLLON CULTURE
Map showing extent of Anazasi, Hohokam and Mogollon homelands (source: wikimedia.org)
The Mogollon Culture was one of four essentially contemporaneous prehistoric Native American cultures that included the Anasazi or Ancestral Pueblo People, the Hohokam, and the Patayan cultures. These cultures thrived a huge area in the Southwestern United States and Northern Mexico that is sometimes referred to as Oasisamerica during the time period of roughly 1200-100 BC until 1300-1450 AD, a time span that has been subdivided into various eras under the Pecos Classification in the Four Corners area.
The large area in which the Mogollon Culture lived included Southern New Mexico and Southeastern Arizona in the U.S., plus Eastern Sonora and most of the Chihuahua states in Northern Mexico. Their cultural boundaries joined with the Hohokam Culture of Southeastern Arizona on the west and the Anasazi or Ancestral Pueblo Peoples Culture of the Four Corners area of Utah, Colorado, Arizona, and New Mexico on the north.
Pottery sherds representing several Mogollon phases. Photo taken during archaeological excavation of a long-term habitation site on the Gila River.
Mogollon Culture Mimbres Phase bowl showing wild turkeys feeding on a large centipede. (Source: wikimedia.org)
The Mogollon Culture is thought to have developed from an earlier nomadic Archaic Culture called the Cochise around 150 AD, at which time pottery was introduced, probably from the south in Mexico. Over the years, archeological investigations of the Mogollon Culture have led to the recognition of several chronological phases in the development of the culture1, including:
- the Georgetown Phase, 550 to 650 AD, characterized by deep, round pit houses for living quarters, development of San Francisco Red, Alma series plainwares and San Lorenzo red-on-brown pottery
- the San Francisco Phase, 650 to 750 AD, characterized by shallow rectangular pit houses with rounded corners, continued production of San Francisco Red and Alma Series plainwares, plus the development of Mogollon red-on-brown and Three Circle red-on-white pottery
- the Three Circle Phase, 750 to 1000 AD, continued use of shallow rectangular pit houses with rounded corners, gradual replacement of San Francisco Red and Alma Series plainwares by Reserve Plain and Corrugated wares, plus development of the Puerco and Mimbres black-on-white pottery
- the Reserve Phase, 1000 to 1125 AD, pit houses giving way to surface pueblos of rock and adobe, development of the Reserve black-on-white pottery
- the Tularosa Phase, 1125 to 1300 AD, rectangular surface pueblos now the preferred building mode plus development of cliff dwellings, introduction of Tularosa black-on-white and some polychrome pottery
- the Mimbres Phase, 1025-1300, rectangular surface pueblos, some attaining large compounds of adjoining room blocks up to 150 or more rooms, development of the classic black-on-white Mimbres pottery which featured intricate geometric designs as well as figures of animals, birds, insects and humans
Starting in 1250 to 1300 and continuing until 1400 to 1450, the Mogollon people began to abandon the large pueblo complexes and disperse. Traditional explanations for this depopulation have centered on climate change, as evidenced by a 50-year period of extended and persistent drought that began in 1250. More recent investigations have considered outside pressures brought on by an influx of other Native American cultures with resulting conflict and warfare.
A HIKE IN THE FOOTSTEPS OF THE ANCIENT ONES
One of the most visually rewarding automobile excursions that can be taken in the vicinity of Casitas de Gila is Sacaton Road. This easily-traveled road (except during wet weather! Inquire first!) is a 25-mile county-maintained, public gravel road that runs west from the Gila River at the small community of Cliff along the south-facing escarpment of the Mogollon Mountains to intersect U.S. Highway 180 just south of the community of Pleasanton. To drive this road is to take a trip back in time to an earlier New Mexico essentially unchanged since pioneer days. For most of the journey the road crosses the southward sloping surface of Sacaton Mesa, a vast flat to slightly undulating expanse of grass-covered ranch lands dotted with juniper and pinyon. Beneath these grasslands lie thick deposits of alluvial sediment that were washed out of the Mogollon Mountains that rise up just a mile or so to the north of the road, over the last several hundred thousands of years.
Sacaton Road looking west along Mogollon Range. Sacaton Mountain (10,600 feet) on far right skyline.
To travel Sacaton Road is to travel a route in continual use for thousands of years. For the early Native Americans it was the obvious best north-south trail because of the gentle terrain, the abundance of game, and, of course, dependable water supply from the numerous creeks that flowed south out of the mountains. We now know that Coronado passed this way too, in 1540, led by Native American guides following in the footsteps of their ancestors. Over the next 300 years Sacaton Road became a primary route for the nomadic Apache, who were none too pleased when the Anglo miners and settlers began to use their trail at first by foot and horseback and later as an established stage coach and freighting route. In those years, to travel what was to become known as Sacaton Road was often a gamble of life or death.
Today, numerous trailheads leading into the Gila National Forest and the Gila Wilderness beyond are accessed along Sacaton Road, each offering unique and spectacular day hikes for those who seek the trail less-traveled in pristine nature.
A HIKE UP SACATON CREEK
On the Sacaton Trail, crossing Sacaton Creek.
Such a trail is the trail up Sacaton Creek, and the one our small band of overstuffed Turkey Day gluttons headed for following the annual day of decadent feasting.
There is a familiar sentiment or feeling that prevails no matter which one of the numerous trails one hikes in the Gila National Forest and Wilderness. Simultaneously, one may experience a mixture of solitude yet peacefulness, wildness with an overarching sense of the primeval, but yet, at the same time, an unexpected feeling of welcoming. For unlike many areas of the Rocky Mountain West, such as the high country of Colorado or Montana or Alaska where one can feel the unease of being the lonely pilgrim in an inhospitable foreign land, for most visitors, the Gila is a welcoming wilderness, a place to feel close to Nature, possibly as never before. Perhaps it is because of the lingering presence of those countless numbers of Native Americans, early explorers, prospectors, miners, pioneers, and ranchers who have all travelled the same trails up the same creek valleys and ridges in days gone by, each engaged in their own optimistic search for sustenance or riches or just the unequaled joy that accompanies any exploration of the unknown.
Through the ponderosas.
Getting higher now.
Thus, regardless of where you hike in the Gila, you are very likely not the first to have travelled there. For the Gila is a young and rugged terrain, an up and down volcanic maze of steep slopes and vertical volcanic precipices, where only the creek valleys and the intervening ridges can be travelled with relative ease. Traveling these trails, the signs of those who have passed before you are everywhere if you are observant and look for them. Or, as more often is the case, they will suddenly pop into your awareness when you least expect it, be it a line of thoughtfully-placed lichen-covered rocks, a bit of old mining equipment, an ancient campsite, a curious slab of petroglyphs placed for all to see, or a well-hidden, mysterious, and haunting pictograph.
Most of the canyon bottom trails into the Gila follow small creeks that are perennial in their lower reaches. Except for the possibility of flash floods during the Monsoon Season or the brief time of high water during Spring runoff, these trails are a delight at all times of the year. Cool and shaded in the Summer and warm and protected in the Winter, these trails can be counted on for a great day’s hike.
This year’s Day after Thanksgiving excursion was such a hike. Our group of 10 moved slowly up the creek, like so many cats, each being attracted to different things – a great photo here, a curious plant there, an unusual rock outcrop. And, of course, the progression slowed to a crawl whenever one of the trail’s unique features came into view — the hundred-year-old cabin with its hand-split cedar shake siding, the colorful waterfall, the gigantic, three-to-four-foot diameter ponderosas, the bedrock-lined pools of aquamarine and topaz waters, the almost hidden foundation of a Mogollon Culture Pit House. And so it went, until stomachs and hikers alike began to growl the familiar refrain – “I’m hungry… is it time to eat yet?”.
A 100 year-old cabin. Was it a miner’s abode or a ranching line-camp?
The numerous pristine pools on Sacaton Creek are a photographer’s delight.
A three-foot Ponderosa soaring into the heavens.
Lichen covered rocks outline the foundation of a Mogollon Culture Pit House.
It’s funny, but great lunch spots always seem to materialize just at the right moment. No sooner did the growling begin then there it was … the perfect spot along the creek, with crystal clear pools lined with numerous slabs and boulders of white volcanic ash-fall welded tuff to sit on, all bathed in glorious warm shafts of light filtering down through the towering ponderosas overhead. Lunchtime!
But, then, just as some had started searching for that perfect personal lunching rock, came the words: “It’s up there, on that cliff! Do you see it?” “No!” “There, beneath that overhang … see it?” And then some of the group that had been here before began to climb up the steep, oak leaf and pine needle covered slope. Hmmm … lunch would have to wait.
The marvellous Frog People pictograph.
The pictographs were spectacular, painted in bright, vermillion red on a smooth joint surface of tan volcanic welded tuff in a sheltered nook in the cliff wall, illuminated perfectly by soft reflected light from the afternoon sun. There were two of them. One big and one small, both carefully drawn. “Why, they are frog people!”, someone said. Anthropomorphic frog people? Or just frogs? “But look at those feet, those huge five-toed hind feet and the small three-toed front feet … or hands?” Hmm… aliens maybe (hey! it’s New Mexico!)? How wonderful! How hauntingly mysterious! Then, of course, came the queries … “Why are they here?” “What could they mean?” “Who painted them and when?” And so the questions and comments went, until all the photographs were taken, and, unable to be put off any longer, the growling stomachs once more made their presence known, calling us down to lunch.
Lunch on Upper Sacaton Creek
A Gambel Oak leaf floating on a crystal pool.
A small waterfall catching the light of the late afternoon Sun.
Now in late afternoon, the hike back down the canyon was a kaleidoscope of intense light and dark shadow as the Late Fall Sun arched ever closer to the west canyon rim. Silence reigned except for the steady murmur of the creek and the occasional jarring call of the raven. With the light now streaming in low from the west, every segment of the trail looked different, triggering the occasional fleeting uncertainty that every hiker has at sometime felt – “Is this the way we came this morning?” Rocks and trees passed by unnoticed, fully shadowed in the morning light, now glowed incandescently in the brilliance of the hard afternoon light, demanding one’s full attention. It was quite warm in the sun, but the shadows already held the chill that would soon fill the canyon. Very soon now the cold air would start flowing down the canyon from the headwaters of the creek on Sacaton Mountain 4,000 feet above.
As the Sun sinks lower, the play of light and shadow increases on Sacaton Creek.
Under the Ponderosas Nature is illuminated …
Arriving back at the trailhead, we lingered a long while, gazing at the surface of a massive rock outcrop we had discovered. The jumble of pictographs pecked into the desert varnish surface of the rock looked back at us in silence, their meanings cloaked in antiquity. Again, the lunchtime queries surfaced in the mind, only to fade away, unanswered as before. But unlike the pictograph frog people, purposefully hidden in that sheltered nook, these pictographs were there for all to see. Yet what once was clear to all that saw them, on this day their meanings were lost and attempts at deciphering them seemed futile. It was like being a visitor in a foreign land looking at faded posted announcements on an old building wall, all written in a language that one cannot read. More Gila mysteries. But with more study, maybe, just maybe next time …
The petroglyphs at Sacaton Creek … what stories could they tell!
It was time to go, the Sun was setting. But the memories of that day would live on and on.
THE DESERT DRY WASH (aka Arroyo):
AN ICONIC LANDFORM OF THE AMERICAN SOUTHWEST
An Exploration into the Natural History of the Dry Wash Trail
at Casitas de Gila Guesthouses in Southwest New Mexico
Looking south up the rugged, ephemeral dry wash of Eliot Canyon. During Summer Monsoon Season this dry wash becomes a high-energy stream capable of transporting large volumes of course sediment and boulders. Following the Ambush at Soldier Hill, the Apache Chief Ulzana and his warriors quite likely used this canyon as an escape route to elude Lt. Fountain and Troop C of the 34th US Calvary.
THE DESERT DRY WASH OR ARROYO:
ICONIC LANDFORM OF OUR WESTERN CINEMATIC FANTASIES
For most adults looking back on our early cinematic adventures, it’s hard to think of a favorite film set in the American Southwest in which the iconic landform of the dry wash or arroyo does not feature in at least one scene of high drama. Who among us does not remember that thrill of a Saturday afternoon when watching the classic, adrenalin-filled chase scene where the good guys and bad guys are blazing away at each other (and typically missing) while galloping mile after mile after mile up or down a sandy, boulder-strewn dry stream bed between towering canyon walls. Or, equally familiar, how we watched in nail-biting suspense as the obligatory ambush scene unfolded on the canyon rim, high above the dry-wash defile a hundred feet below, where the hapless and unsuspecting soldiers, wagon train, or strongbox-carrying stage coach would soon pass. It was exciting stuff of which that we never tired.
Looking east up the large intermittent stream dry wash of Little Dry Creek Canyon towards Soldier Hill in the distance, site of the ambush of Lt. Samuel Fountain and Troop C of the 34th US Calvary at Soldier Hill by the Apache Chief Ulzana and his warriors on December 19, 1885.
Yet the fact is that these scenes were more than just another artifice in fantasy of Hollywood fabrication. For the most part, the human dramas they portrayed were historically accurate, real-life events that played out over and over again during the golden years of America’s pursuit of its Manifest Destiny. A well-documented local example of one such event was the Massacre at Soldier Hill, which took place on December 19, 1885, when the Apache Chief Ulzana and about nine warriors ambushed Lt. Samuel W. Fountain and the 34-man strong C Troop of the 8th US Calvary while on patrol in the Mogollon Mountains. The ambush took place as the soldiers were coming up a steep grade on a small hill located on the north side of a dry wash called Little Dry Creek, located about 20 miles north of the Casitas. Taken completely by surprise, Lt. Fountain’s patrol suffered a loss of five men killed and three wounded before the calvary regrouped and counter attacked. As the soldiers advanced again, Ulzana and his band abandoned the high ground and slipped away to the west, heading down the dry wash of Little Dry Creek canyon about two miles before, quite likely, heading south up the dry wash of Eliot Canyon. From Eliot Canyon, they would have had access and safe passage out of sight into a subsequent maze of rugged dry washes, eventually leading them to the Mule Mountains, and from there, further south to a mining community near Carlisle, NM, where they killed three men and wounded several others on Christmas Eve.
As countless historical and archaeological research studies have documented, the dry washes of the Southwest Desert served as much-used corridors of transit and passage for both humans and wildlife alike throughout both historic and pre-historic time. And despite their dry, dusty, and seemingly insignificant and unimportant appearance, they constitute one of the most critical landform elements in the physical development, evolution, and ecologic sustainability of the arid and semi-arid landscape of the American Southwest.
DEFINING THE DRY WASH OF THE AMERICAN SOUTHWEST
Looking downstream at the intermittent stream dry wash of Little Dry Creek, 2 miles from its confluence with the larger intermittent stream dry wash of Big Dry Creek which flows into the perennial stream of the San Francisco River.
The terms dry wash, wash, gulch, and arroyo are informal terms that tend to be used somewhat interchangeably on a regional basis both in written and spoken word by people living or working in the American Southwest. The simplest definition would be any watercourse or stream bed regardless of size that has flowing water only part of the year. A more definitive definition would take into account the scale of the watercourse both in terms of physical size and volume of water flow, as well as periodicity and duration of flow events1. In this context, a brief definition of the three types of streams found in the American Southwest is useful.
Perennial streams or rivers are those watercourses where water flows continuously all year. As any state map will show, perennial streams are an extremely rare feature in the arid and semi-arid Southwest American landscape. The Gila River, which exits the Mogollon Mountains and the Gila Wilderness five miles northwest of the Casitas, is a perennial stream.
Much more common are those watercourses classified as intermittent streams, where portions of the stream flow continuously only at certain times of the year, such as during seasonal snow melt, or flow from a local ground-water source such as a spring. Intermittent streams can vary in length from short to extremely long, often stretching for many miles across the landscape. Little Dry Creek with its headwaters in the Mogollon Mountains is a classic example of an intermittent stream, having a Spring flow from melting snow high in the Gila Wilderness and sporadic flows during the Summer Monsoon season.
Looking southwest upstream at the ephemeral stream dry wash of Eliot Canyon which drains the vast mesa lands of Cactus Flat Country.
On a much smaller scale, and even more numerous, are those watercourses classified as ephemeral streams, where the water flows as runoff for only very brief periods of time in response to local precipitation. A defining technical characteristic of ephemeral streams are those watercourses where the water running in the channel is at all times separated from, and unrelated to, the ground water table.
In the arid and semi-arid American Southwest, both intermittent and ephemeral stream watercourses are referred to as dry washes, washes, gulches, or by the Spanish term arroyos.
In many ways, desert dry washes can be considered as “corridors of life” that form a branching network of sustenance across this arid and semi-arid landscape, providing water, food, and shelter to the indigenous animals, birds, and insects that live in and near them, as well as those that are just migrating or passing through. For humans, from pre-historic times up through the early pioneer days, in addition to serving as the best likely source of water, food, and shelter, they served as reliable primary foot and horse trails and eventually early roads that provided the easiest and most direct routes through this rough and mountainous arid landscape.
Today, in addition to serving in the above mentioned functions, these networks of dry washes are recognized as a critical and strategic natural resource that must be protected and preserved wherever and whenever possible. Not only are they invaluable, both in maintaining and sustaining a complex wildlife biodiversity increasingly threatened by encroaching ongoing human development, but also they constitute a strategic and critical resource for replenishing, preserving, and sustaining local and regional water supplies through the continual recharging of ground water aquifers throughout the arid and semi-arid Southwest.
AN EXPLORATION INTO THE NATURAL HISTORY OF THE DRY WASH TRAIL,
A SMALL DRYWASH AT CASITAS DE GILA GUESTHOUSES
As defined above, dry washes develop along both intermittent and ephemeral streams, and can vary in scale from short features less than a mile in length to landforms stretching for many miles across the landscape. Regardless of scale, however, upon close inspection most dry washes within a region will exhibit many similar physical and ecologic features along their course since they result from the same geologic, climatic, and hydrologic processes acting over hundreds to many thousands of years.
Dry washes are a common landform at Casitas de Gila and the surrounding area, where numerous intermittent and ephemeral streams actively dissect a rugged mesa and canyon landscape lying between the Gila River valley lowlands and the surrounding uplifted mountains of the Mogollon and Pinos Altos ranges within the Gila Wilderness to the north, the Burro Mountains to the south, and the western end of the Silver City Range.
The Dry Wash Canyon Trail
The Dry Wash Canyon Trail is one of several trails established within the Bear Creek Nature Preserve at Casitas de Gila Guesthouses to provide access and up-close and personal experience of the various diverse physiographic features, geology, biology, and ecology that are found along this portion of Bear Creek. Bear Creek is a major tributary of the Gila River, flowing westward some 25 miles from its headwaters at the old mining town of Pinos Altos, about 6 miles north of Silver City. In its upper reaches, the waters of Bear Creek are perennial, eventually becoming intermittent just downstream from the southern boundary of the Casitas de Gila land as the stream gradient (slope) decreases towards its junction with the Gila River.
The Dry Wash Trail at Casitas de Gila follows an ephemeral stream dry wash canyon that drains the west facing slopes of North and South Peaks before emptying into the perennial stream of Bear Creek. A short distance downstream from the Casitas’s southern boundary, Bear Creek becomes intermittent.
Major geologic features and 4 Segments of Dry Wash Trail Canyon
The Dry Wash Canyon Trail is located within the southern portion of Casita de Gila land. As is shown in Figure 1, the trail extends southeast and then east from Bear Creek up a short (0.7 mile) dry wash canyon that has been cut by an ephemeral stream acting over many thousands of years. The headwaters of the canyon’s drainage lies at an elevation of 5,460 feet in a small topographic saddle between North and South Peaks, just east of the Casitas. From there it eventually drops some 770 feet in elevation to its junction with Bear Creek at an elevation of 4,690 feet.
The course of the Dry Wash Trail Canyon can be divided into four segments based on the gradient or slope of the stream bed, the underlying geology, and the dominant and controlling geological processes, biology, and ecology. From top to bottom, they are:
1. Upland Drainage Basin (5,460 feet down to 5,040 feet in elevation)
Contact between Segment 1 of the Upland Drainage Basin and Segment 2 as defined by a high-angle normal fault. Volcanic rhyolite ash fall welded tuff exposed on right (east) side of the fault and Sedimentary Gila Conglomerate exposed just to the left of the fault. Note thin soil with vegetative cover of native grasses, Pinon Pine, (with Scrub Oak behind it) and Honey Mesquite in upper right. Casitas de Gila Guesthouses can be seen in center distance.
Segment 1 of the canyon is steep, the bed of the watercourse having gradients of up to 26° or more and averaging 22°. In this segment, the main watercourse of the drainage basin has been cut into 28 million-year-old volcanic rhyolite welded ash fall tuff bedrock by on-going active weathering, erosion, and downcutting. Only a thin skim of residual soil remains, held in place by a sparse cover of native grasses, and a scattering of native grasses, Sotol, Scrub Oak, One-seed Juniper, and Pinon Pine.
The lower end of this segment is marked by the presence of a major north-south trending, high angle normal fault. This fault separates the uplifted volcanic rhyolite welded ash fall tuff on the east side of the fault from the down-dropped 5-10 million year old sedimentary fluvial Gila Conglomerate on the west side of the fault. The fault is extensive and can be traced across the western face of South and North peaks east of the Casitas to Turtle Rock on the north by the obvious visual change in slope of the mountainside from the average slope of 22° on the uplifted volcanic welded tuff, to an average 11° slope on the down-dropped sedimentary Gila Conglomerate.
2. Upper Canyon Dry Wash Erosion Within Gila Conglomerate (5,040 feet down to 4,840 feet)
Segment 2 of the Dry Wash Canyon is cut down into the near-horizontal layers of the Gila Conglomerate, with the bed of the watercourse having an average gradient of about 11°. Along this segment, the floor of the canyon is characterized by extensive exposures of Gila Conglomerate as a result of on-going active weathering, erosion, and downcutting. Throughout this segment, all eroded sediment is transported downstream, except for the largest boulders (up to 6 feet in diameter) that have come to a final resting place in the lower part of this segment of the canyon. These large boulders are not being carried further downstream due to the reduction in velocity and energy of the flash-flood waters caused by the reduction in gradient of the watercourse bed.
Gila Conglomerate bedrock exposed Segment 2 in stream bed of canyon, scoured clean of sediment except for loose course gravel left on surface by earlier flash flood.
Large lichen-covered pyroclastic boulder left on Gila Conglomerate bedrock exposed in stream bed of canyon in Segment 2. Extensive covering of lichens shows boulder has not moved in several hundred years. Origin of pyroclastic boulder is problematic in that there are no known exposures of this pyroclastic rock type currently exposed in the upstream drainage of this drywash.
Examination of the largest boulders in this segment reveal interesting facts:
- The presence of extensive growth of large lichens on the rocks, with diameters of individual lichens up to 4 inches in diameter, suggests that these boulders have not moved for several hundred years or more, indicating a time in the past when the velocity and volume of flash-flood waters in the canyon were significantly higher; a velocity and volume which haven’t reoccurred since.
- The composition of some of these boulders is neither rhyolite welded tuff nor Gila Conglomerate, but is that of a volcanic pyroclastic rock, a rock type which is not known to occur anywhere upstream in the bedrock exposed in the present canyon’s drainage basin below North and South Peaks. While there are such pyroclastic rocks a mile or so to the east and to the north in different drainage basins, these boulders present a dandy little geologic mystery just waiting to be solved!
Sides of the canyon in Segment 2 have a thicker cover of soil than Segment 1, in which the soil is derived from the weathering of the softer Gila Conglomerate as opposed to the harder rhyolite welded tuff. On the dry, south-facing slopes of the canyon, this soil supports a vegetative cover dominated by native grasses such as Side-oats Gramma, Honey Mesquite, Western White-thorn Acacia, and Oreganillo. On the wetter north facing slopes, Side Oats and other native grasses, Scrub Oak, One-seed Juniper, and Pinon dominate.
3. Middle Canyon Dry Wash Erosion Within Gila Conglomerate (4,840 feet down to 4,800 feet)
Looking upstream at a 6-ft. dry wash waterfall or pourover in Gila Conglomerate bedrock in Segment 3. This feature is formed when the downcutting of the dry wash stream bed encounters a layer of rock that is much more resistant to erosion than the rest of the bedrock. In this case, it is due to a better-cemented layer of much larger cobbles and boulders of volcanic rock.
Looking downstream standing on top of and at the edge of 6-ft. waterfall or pourover shown in adjacent photo on left. All of these large cobbles and boulders are strongly cemented in the Gila Conglomerate presenting a highly resistant layer to erosion.
Segment 3 of the Dry Wash Canyon is cut deeper into the near-horizontal middle layers of the Gila Conglomerate, with the bed of the watercourse having an average gradient of about 7°. In this segment of the canyon, weathering, erosion, downcutting, and non-deposition still prevail, with all eroded sediment still removed from the stream bed by active downstream transport. Active erosion of the canyon floor dominates throughout this segment with little or no sediment remaining over the Gila Conglomerate bedrock.
Vegetation on the dry south-facing and wetter north-facing slopes of the Canyon is similar to that of Segment 2.
Looking downstream in the lower part of Segment 3. Here the Gila Conglomerate bedrock as exposed on both sides of the canyon is quite soft and easily eroded, leading to rapid down downcutting of the dry wash stream channel.
4. Lower Canyon Dry Wash Deposition Within Gila Conglomerate and Across the Bear Creek Floodplain (4,800 feet down to 4,690 feet at Bear Creek)
Rapid lateral erosion of the sides of the dry wash canyon takes place in the lower part of the canyon in Segment 4 where the Gila Conglomerate is overlain by deposits of loose, unconsolidated sediment. Here, this One-seed Juniper illustrates this lateral erosion by the exposure of approximately 3 vertical feet of the tree’s root system.
In Segment 4 of the Dry Wash Canyon, the slope of the bed of the watercourse decreases rather abruptly to a slope of about 4° as it approaches its junction with Bear Creek. This reduction in slope is a critical one in that it exceeds a threshold value where the dominant and controlling geologic processes operating within the canyon undergo a fundamental change. The change, in this case, is from an ephemeral stream of erosion that is actively eroding, downcutting, or in geological terminology, degrading its stream bed as described in Segments 1, 2 and 3; to an ephemeral stream of deposition that is actively building up, raising, or in geological terminology, aggrading its bed through the deposition of transported sediment as discussed below.
Layers of Gila Conglomerate exposed on the arid north side of dry wash canyon in Segment 4.
Western White-thorn Acacia (Vachellia constricta) growing along edge of dry wash stream bed in Segment 4.
Looking east and upstream in upper part of Segment 4. South Peak can be seen in the distance.
Plants and wildlifes are much more diverse and abundant within Segment 4 than in Segments 1-3. This is because of the presence of water that is retained for varying lengths of time within the sediments covering the stream bottom following the periodic flash-floods that occur during the year. The distribution of the various plant species within Segment 4 is highly variable, depending upon the amount and time duration of the retained water, which in turn are a function of the thickness, size distribution, and location of these unconsolidated deposits of sand and gravel that cover the Gila Conglomerate bedrock. Characteristic plants of Segment 4 include Desert Buckthorn, Desert Willow, Squawbush or Skunkbush, Prickly Pear Cactus, Cane Cholla Cactus, Wait-a-minute Bush or Catclaw, Honey Mesquite, and Thread-leaf Snakeweed.
Looking downstream in Segment 4. In Segment 4, the Gila Conglomerate is buried under thick deposits of sand to gravel sediment carried downstream from Segments 1, 2, and 3.
In the lower parts of Segment 4, the dry wash channel widens considerably. With each successive flash-flood the stream channel shifts back and forth over this low slope surface as rapidly deposited sediment blocks old channels and new ones are formed.
Here Segment 4 of the Dry Wash Trail Canyon approaches Bear Creek, flowing from right to left and out of sight just beyond the row of young, white-barked cottonwoods in the middle distance. Here it flows out across the Bear Creek floodplain depositing sediments carried downstream from Segments 1-4, which are carried away when Bear Creek floods.
GEOLOGIC PROCESSES AND FACTORS CONTROLLING THE FORMATION OF
THE CLASSIC LANDFORM OF THE DESERT DRY WASH
The development of the desert landform known as the dry wash as found in Segment 4 of the Dry Wash Canyon Trail at Casitas de Gila can be summarized by the following interacting geologic principles, processes, and sequence of events.
- It is a fundamental principle that as the gradient of a stream bed decreases going downstream, it results in a corresponding reduction in the velocity and energy of the water flowing down the stream.
- As the velocity and energy of the flowing water in a stream is reduced, this in turn results in a corresponding decrease in both the volume as well as grain size of sediment that can be transported by the stream.
- Dry wash canyons are formed by ephemeral streams resulting from short-term precipitation events that produce short-lived, but high-energy, flash-floods within the canyon. In the Dry Wash Trail Canyon, the steep slopes of Segments 1-3 (22° to 7°) are characterized by having extremely high velocity and energy downstream runoff during precipitation events that cause erosion and downcutting of the stream bed, with all eroded material being carried downstream. When this transported eroded sediment reaches Segment 4, where the gradient of the canyon floor is much less (4°), the velocity and energy of the water is reduced to the point were the runoff water can no longer transport the sediment, causing it to be the deposited over the stream bed, burying any Gila Conglomerate bedrock exposed in the stream bed in the process.
- In a dry wash stream system, however, it is important to note that the sediment deposition as observed in Segment 4 is typically only temporary, since these sediments may only remain in a particular place until the next flash-flood occurs. When the next flash flood does occur, depending on the magnitude and duration of the flood, the previously deposited sediments may be washed away, often right down to the bedrock itself, only to be subsequently replaced by new sediments in transport downstream that are deposited when the flood waters subside. Over long periods of time, the repeated bedload transport of this sediment downstream across the bedrock surfaces exposed during the periodic flash floods will slowly grind down the surface of the bedrock, resulting in a gradual lowering of the canyon bottom.
It is through these processes, then, that the classic and unique landform of the Dry Wash of the desert Southwest is formed and evolves. For many people, especially those new to the Southwest, the Dry Wash may go completely unnoticed or merely thought of as an unimportant, static landform where nothing ever changes. The true reality, however, is that the Desert Dry Wash is a highly dynamic and ever-changing landform that is critical to the long-term stability and sustainability of the life forms that make their home there.
Looking upstream from the Bear Creek floodplain at the lower end of Segment 4 of Dry Wash Trail Canyon. Note trail marker arrow in lower left.
1. Ephemeral Streams Report (.pdf file)