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)
THE GREAT BEAR CREEK FLASH FLOOD OF SEPTEMBER 22, 2014
Documenting a Major Flash Flood on Bear Creek at Casitas de Gila Guesthouses
caused by Remnants of Hurricane Odile in Southwest New Mexico
View of February 12, 2005 Flood at near peak flow, looking north from Casitas towards Turtle Rock. Photo illustrates how major floods will inundate the entire Bear Creek floodplain and lower stream bank terraces. Because the September 22, 2014 Flood peaked and receded before dawn there are no comparable photos.
Hammock below Casitas at peak flow of February 12, 2005 flood. Water level at this time approximately 8 feet above normal water level of Bear Creek. Debris left behind in trees near the hammock by the September 22, 2014 flood showed that this same hammock was two feet under water in the 2014 Flood, or between 10 and 12 feet above normal water level!
THE SETUP: HURRICANE ODILE MAKES LANDFALL
ON MEXICO’S BAJA CALIFORNIA PENINSULA
On Sunday night, September 14, 2014, Hurricane Odile came ashore on Mexico’s Baja California Peninsula, making a direct hit on the resort tourist destination of Cabo San Lucas as a Category 3 hurricane with sustained winds of 125 mph. It was the strongest hurricane to hit the Peninsula in recorded history. After inflicting devastating damage and chaos in Cabo, the hurricane took an unusual northward path along the Baja Peninsula towards Arizona, reaching the U.S. border on Friday, September 19. Passing into Arizona, the storm then took a turn to the east towards Southern New Mexico and West Texas. Although the winds rapidly decreased upon entering the U.S., the degraded storm succeeded in dragging a huge plume of moisture into the Southwest, triggering several days of rain and thunderstorms as it travelled eastward, and resulting in extreme flooding and flash floods in SE Arizona and SW New Mexico.
A NIGHT TO REMEMBER
The National Weather Service (NWS) had predicted that over the weekend and early into the coming week of September 22 there would be a high probability of showers and thunderstorms, with some local flooding and flash floods as the remnants of Storm Odile made its way from Arizona east towards Texas. Indeed, on September 20 and 21, patchy showers, thunderstorms and localized flooding occurred throughout Southwest New Mexico, although only small amounts of rain and only a brief, small rise in Bear Creek were recorded at the Casitas. By Sunday evening, September 21, NWS radar was showing that the most intense thunderstorm activity stemming from the rapidly-dissipating Odiel had now moved east of the Casitas and the surrounding Gila area towards Truth or Consequences, NM, suggesting that the potential for significant flooding was over. Such was not the case.
At about 2 AM on Monday morning, September 22, the first of several large thunderstorms made a direct hit on the Casitas. With the pounding of the first blast of rain on the roof, a check with the NWS radar showed that the thunderstorm cell had come out of the Northeast. With increasing consternation, it was quickly determined that not only was it a large cell, but there were several large cells lined up behind it, all of which were tracking straight towards the Casitas. Taken together, the numerous cells covered a wide swath that essentially covered the entire drainage basin of Bear Creek, extending all the way upstream from the Casitas to Pinos Altos, 25 miles to the northeast. If these cells remained active for any length of time, it was pretty certain that Bear Creek was going to flood. Judging by the persisting deep red to purple colors of the cells on the radar as they slowly moved down Bear Creek, it was going to be a major flood.
All of the thunderstorm cells remained intensely active until 4 AM, when the last of them finally passed over the Casitas. By this time Bear Creek was already roaring unseen in the darkness 100 feet below in the canyon below the Casitas. By the sound of it, a significant flash flood was underway, but it would be another two and a half hours before the first light of day would illuminate the magnitude of what was actually taking place.
A FLOODPLAIN OF CHANGE
Peering down into the canyon in the early morning light, one could see that the peak of the resulting flash flood had already passed by and that Bear Creek was still swollen out of its banks and running strong.
Here and there chaotic masses of vegetative debris could be seen hanging high in the branches of the cottonwoods and willows several feet above the floodwaters that still ran across the entire floodplain and onto the adjacent stream terraces below. Over the main channel an endless parade of logs, branches, and mats of other floating debris shot by in the churning waters.
Late in the day on Monday, when the Creek had dropped substantially from its highest stand, some guests staying at the Casitas ventured down to take a closer look at the still roaring Bear Creek, following a trail that leads down to a hammock that is situated on a creek bank terrace about 6 feet above the main channel, on the Casita side of the Creek. Upon their return they estimated that the hammock (still intact and hanging on its chains) had been submerged about 2 feet underwater at the peak of the flood on the basis of debris caught in adjacent trees, which would put the maximum depth of the Creek over the channel at about 10 feet. If verified, this figure would mean that the September 22 floodwaters had attained the greatest depth of any flood experienced in the 16-year history of Casitas de Gila Guesthouses, the previous record being an 8-foot depth from the February 12, 2005 flood. That flood had resulted when a warm front coming up from Mexico brought 2.5 inches of slow rain to the area over a 52-hour period, which succeeded in melting all of the snow pack in the high mountains of the Gila Wilderness lying a few miles north and northeast from the Casitas.
It would be three days before the floodwaters receded to the main channel and the velocity dropped enough that one could cross the creek safely to survey and record what had taken place. Starting at the downstream boundary of the Casita land and following the course of the Creek two-thirds of a mile to the upstream Casita boundary, a close inspection revealed that the guest’s estimate was actually conservative in that the floodwaters had in places reached depths of 11 to 12 feet, based on debris lodged in the trees bordering the main channel.
SOME BASIC PROCESSES OF STREAM CHANGE IN BEAR CREEK
Before illustrating and discussing the changes that took place on Bear Creek over the three-day period of September 22-25, 2014, it is useful to review some of the basic processes that affect how a stream evolves and changes over time.
The width of the active Bear Creek floodplain over the Casita lands, including the first stream bank terraces, varies from 120 feet at the most narrow point to 250 feet at the widest. Although rather confined, over time the Creek still manages to display some of the features of a meandering stream. In the 16 years of observation at the Casitas the stream has undergone significant change, including:
- Channel migration or meander from one side of the canyon to the other, producing slip-off slopes, point bars, stream cut cliffs, and cut-off channels or chutes
- Deposition and build up of sediments up to 6 or 7 feet thick across the floodplain, ranging from fine sand to boulders 3 feet in diameter
- Erosion and scouring of cut-off channels up to 6 or 7 feet deep
- Exposure or burying of the Gila Conglomerate bedrock underlying Bear Creek by unconsolidated modern sediments in transport down the Creek
Looking upstream, photo illustrates formation of slip-off slope and point bar on east side of main channel and cut-bank on west side of channel, following drop of flood waters to normal flow.
Photo illustrating cut-off channel scoured by flood waters abandoning curve in main channel (flowing from upper left of photo out of sight behind trees to right side of photo and then to lower left of photo) to flow directly across floodplain.
All creeks and rivers carry various amounts of solid sediment and dissolved matter downstream. This material is referred to as stream load, which is classified into three types:
- Bed load – Coarse and heavy sediment, ranging in grain size from silt and sand to pebbles, cobbles, and boulders, that travel downstream along the bottom of the stream either in constant contact, such as rolling or sliding (traction load), or by hopping and skipping and bouncing (saltation load)
- Suspended load – Fine sediment, such as clay, silt, and sand, that is transported downstream suspended in the water column by turbulence and currents
- Dissolved load – Invisible to the eye, this type of stream load consists of chemical ions of various elements that are dissolved in the water
All streams, from small creeks to large rivers, are typically in a state of dynamic flux, attempting to achieve a state of equilibrium where there is neither erosion nor deposition of stream load along the stream channel. Such equilibrium is only rarely and briefly achieved as fluctuation in the volume and velocity of water, plus the gradient or slope of the channels, vary constantly. During floods and flash floods such fluctuations increase exponentially, both in magnitude as well as spatially, as flood waters leave their channels and flow out across the floodplain, and, in the case of large floods, ultimately submerge the adjacent river bank terraces. When the floodplain is covered with riverine forest, as is the case of Bear Creek in front of the Casitas, the resulting fluctuations are extremely chaotic as trees are undercut and topple or masses of floating debris of logs and vegetative matter lodge against standing trees forming localized dams to the churning waters.
A PHOTO DISCUSSION OF THE EFFECTS OF THE GREAT BEAR CREEK FLASH FLOOD OF SEPTEMBER 22, 2014
A Comparison of the Magnitude, Duration, and Effects of the 2005 and 2014 Floods
Vegetative debris caught on willow tree at edge of main channel. Scarred bark just above debris (probably result of hit by floating log) is about 12 feet above main channel normal water level.
Debris caught on 4-1/2 foot Casita horse corral fence. Flood-scoured corral is located on top of first stream bank terrace approximately 7 feet above normal water level in main channel.
In terms of duration, the 2005 flood went on relatively unabated for nearly two weeks because of a warm front that came up from Mexico dropping 2.5 inches of widespread rain over a period of 52 hours that covered not only the entire Bear Creek drainage system, but also melted all of the snowpack in the adjacent mountains. In contrast, the 2014 flood was essentially a flash flood resulting from only a few hours of intense thunderstorms having extreme precipitation rates of 1 to 2 inches per hour that were confined to the center of the Bear Creek drainage basin. So while the 2014 flood reached greater depths, much greater volumes per second, and higher velocities, this greater intensity only lasted a few hours in comparison to the less intense, but much longer lasting 2005 flood.
Surface of stream bank terrace 6 feet above main channel cut away by erosion and scoured to depths of three feet or more by flood waters.
Looking upstream on floodplain at thick deposits of sand deposited downstream from the dense stand of cottonwood and willow in background which slowed water flowing across floodplain sufficiently so that suspended load of sand sediment would be deposited.
Looking upstream on floodplain where debris dams on right side of photo have concentrated waters flood waters on floodplain to selectively scoured away all fine silt and sand to leave a cut-off channel paved with course cobbles and boulders.
Consequently, the change affected by these two floods upon Bear Creek Canyon was quite different. These changes can be summed up as large scale but gradual changes affected by the 2005 flood as opposed to small scale but catastrophic changes for the 2014 flood. For example: in the 2005 flood the main channel of Bear Creek was shifted from the eastern edge of the canyon some 200 feet to the west to where it is now located directly below the Casitas on the western edge of the canyon. By contrast, the 2014 flood produced numerous, but localized, deeply scoured channels and thick, irregular mound-shaped deposits of sand to coarse gravel and boulders across the floodplain, as well as uprooting trees and stripping vegetation from bedrock surfaces.
Clump of several 20-foot willow trees that were growing on stream bank on west side of main channel that were undercut and toppled by flood. Mass of upstream-facing roots will act as a dam-like barrier to prevent further erosion of the Creek bank at this spot and cause migration of the main channel to the east (toward the camera).
Gila Conglomerate bedrock exposed on south side of main channel when flood waters stripped away the cover of creek bank vegetation shown on left side of photo. Thus exposed, bed-load sand and gravel carried by future floods will now resume the wearing down of the bedrock surface continuing the eternal downcutting of Bear Creek Canyon.
Another critical factor responsible for the vast difference in affects resulting from the 2005 and 2014 flood is the dramatic increase in floodplain vegetation between June 2005 and September 20, 2014 (just two days before the flood) as illustrated in the these photos.
View of Bear Creek floodplain looking north upstream towards Turtle Rock on June 18, 2005. Note width of channel and and paucity of floodplain vegetation when compared to 2014 photo on right.
View of Bear Creek floodplain looking upstream towards Turtle Rock on September 20, 2014, two days before the Great Flash Flood. Note narrow width of main channel and extensive development of riverine forest across the floodplain on east side of Creek (right side of photo) in comparison to 2005 photo on left.
In addition to the increase in density of the maturing riparian forest over the floodplain, note how the main channel in 2014 has become constricted in width, resulting in both active down cutting of the main channel itself while simultaneously forcing a high volume of rapidly-moving water out across the floodplain. The result of these high-energy flood waters surging across the densely-forested floodplain produced massive change across the floodplain in terms of the erosion and scouring of new cut-off channels, plus large-scale build-up of adjacent stream bank terraces of both fine and course suspended and bed load material in response to localized damming effects of flood-transported debris being caught against trees on the floodplain which resulted a reduction in the velocity of the water resulting in deposition of stream load.
Localized debris dams slow water movement over floodplain causing deposition and buildup of fine suspended load sediment.
Localized debris dam on floodplain causing deposition and buildup of coarse gravel and boulders.
A SUPER ABUNDANCE OF HIGH DESERT NECTAR SLURPERS ABOUND
WITHIN THE BEAR CREEK NATURE PRESERVE
August is High Season for Hummingbirds and Butterflies
at Casitas de Gila Guesthouses
Female Black-chinned Hummingbirds
Male Black-chinned Hummingbird (on left)
Painted Lady, Brush-footed Family
Cloudless Sulphur, Whites and Sulphurs Family
THE BEAR CREEK NATURE PRESERVE
In 1999, the Bear Creek Nature Preserve was created and set aside in Bear Creek Canyon at Casitas de Gila Guesthouses. Initially comprising some 70 acres, the Reserve was gradually enlarged to 265 acres. Six miles of maintained hiking trails along three-quarters of a mile of Bear Creek Canyon allow Casita guests to explore the diverse habitats that exist along and adjacent to Bear Creek. Over the past 15 years, the Nature Preserve has been an on-going source of pleasure and delight for both guests and hosts alike, allowing them to observe the various cycles of natural change that have evolved along this stretch of Bear Creek.
Initially this segment of the Bear Creek Canyon consisted of an over-grazed, straight channeled, gravel and debris choked and scoured floodplain, essentially barren of any vegetation over six feet in height, bordered by thousand-year-old mature-growth vegetated river terraces on both sides of the floodplain. These stream terraces, once farmed by the ancient Mogollon Pueblo Culture, were being actively eroded and cut away with every succeeding flood that came down Bear Creek. With fencing and removal of the cattle that had overgrazed the floodplain for many years, the young Cottonwood, Willow, Sycamore, and Seep Willow were able to take root, grow, and stabilize the eroding creek banks and immediately began to reestablish the natural riverine forest in the floodplain.
Looking North up Bear Creek Nature Preserve from Casitas de Gila Office, July 9, 2001
Looking North up Bear Creek Nature Preserve from Casitas de Gila Office, July 26, 2013
Today, the creek bottom within the Nature Preserve is unrecognizable from its former state 15 years ago. The vegetation over the floodplain has evolved and matured into a diverse riverine forest dominated by stands of 30- to 80-foot young cottonwoods, sycamores, and willows that border a now meandering creek and have stabilized the formerly eroding old stream terraces. A complex vegetative diversity of trees, shrubs, and flowering weeds and grasses now abounds over the floodplain and adjacent terraces, providing year-round habitat and food for an equally diverse assemblage of animals, birds, and insects.
HUMMINGBIRDS GALORE IN THE HIGH DESERT
“Bon Slurpatit!” A group of hummingbird friends sit down for breakfast at the Casitas. From L to R: Perched Male Back-chinned, Hovering Male Black-chinned, Hovering Female Rufous, Hovering Female Black-chinned, Hovering Male Black-chinned
For 16 years now, guests at Casitas de Gila Guesthouses have been treated to the spectacular annual gathering of hummingbirds that takes place between their arrival in late March until their departure in early October. Initially the number of hummingbirds who decided to visit during the “Season” at the Casitas was modest, but over the years the number has grown exponentially, as evidenced by the volume of sugar water nectar consumed by the voracious slurpings of these amazing little creatures! This year, for example, the Casitas will use approximately 150 pounds of granulated sugar to make the 85 gallons of nectar that will be consumed over the roughly 200-day season.
“Look at Me, Mr. Rufous”. (Mr. Rufous has now joined the others for dinner)! “As a Black-chinned male, I have a purple throat patch, and you don’t!”
“Yeah, well, who cares Mr. Black-chinned. I’m the American Birding Association Bird of the Year!”
There are some 325 to 340 different species of Hummingbirds in the World (depending on who is counting), all of which are found in North, Central and South America. Twenty-seven species of of these hummingbirds have been reported in the United States, and 17 are reported in the State of New Mexico. Here in Southwest New Mexico, there are 7 species of hummingbirds reported from the Gila National Forest (bird checklist available for download as .pdf file), 5 of which visit the Casitas over the course of the Summer. Most abundant, first to arrive, and last to leave are the Black-chinned Hummingbirds (Archilochus alexandri). The Broad-tail Hummingbird (Selasphorus platycercus) is also a common visitor. The Rufous Hummingbird (Selasphorus rufus) comes in late Summer, arriving in July and peaking in August. The Calliope Hummingbird (Selasphorus calliope) and the Magnificent Hummingbird (Eugenes fulgens) are much less common, occasionally seen in August and early September.
“Oh yeah, well then Mr. Rufus, just take a look at my Mrs. with her iridescent green colors and those white spots on her tail feathers!”
“Not impressed Mr. Black-chinned, take a look at my Mrs.’s iridescent green and copper colors, plus the white tail feathers to match!”
Hummingbirds are the smallest birds in the world, and weigh between from 0.07 to 0.7 oz. (2 to 20 grams). In their research on hummingbird foods and feeding, Hainsworth and Wolf have shown that Ruby-throat Hummingbirds can consume up to 14 times their weight in sugar water from artificial feeders in a single day when filled with the typical 1:4 concentration of table sugar and water! They also found that the sugar concentration in wildflowers could be up to 8 times greater than the typical 1:4 sugar water concentration. Since hummingbirds at the Casitas have access to both artificial feeders and wildflowers, the average hummingbird at the Casitas probably consumes at least several times its weight in nectar in the form of many small meals slurped up from the Casita feeders. In addition, the hummingbirds will also consume a sizeable daily intake of small insects and spiders that provide the essential proteins, amino acids, vitamins, and minerals that flower nectar and sugar water nectar do not contain. Some of these insects they find around the Casitas, but most are caught during numerous forays into the riparian forest along Bear Creek, 100 feet below the Casitas. A primary attraction for the large number of hummingbirds that visit the Casitas is the presence of the extensive riverine forest of the Bear Creek Nature Preserve along Bear Creek, where a profusion of wildflowers and small insects are found during the Summer months.
Breakfast finished, Mrs. Black-chinned quickly flits to her man’s side, chirping for Mrs. Rufous to “Buzz off!”. Mr. Black-chinned seems to know he’ll soon be catching it from the Mrs., while Mr. Rufous has seen it all before and goes back to slurping.
Meanwhile, although very much aware of how the brazen Mrs. Rufous is showing off for Mr. Black-chinned, Mrs. Black-chinned decides to finish her breakfast before taking action.
The most common, and average-sized, hummingbird at the Casitas is the Black-chinned Hummingbird, which has an average weight of about 0.15 oz. Considering the research of Hainsworth and Wolf, if each of these hummingbirds consumed, say, just 6.5 times its body weight (or about 1.0 ounces of Casita sugar water nectar) a day, that would equate to about 0.1 cups per day (1 cup sugar water nectar weights 10.6 oz.). Doing the math, the 85 gallons of sugar water nectar that will be consumed at the Casitas this year amounts to approximately 13,600 hummingbird meals fed over the approximately 200-day season, for an average of 68 bird-meals a day. The actual number of birds present at any given time varies greatly during the season. Starting out with only a few in March, their numbers gradually increase as the Summer progresses, until reaching a peak in August, when the greatest diversity and number of wildflowers are blooming along Bear Creek. At this time, the feeders at the Casitas are literally swarming with the little birds from dawn to dusk.
If one takes the time to read and study the facts about the life history of hummingbirds, one quickly comes to understand that they are truly amazing little birds. Hummingbirds are the smallest birds in the world, and have the highest metabolism of all animals, with a resting heart rate of around 450 beats per minute which can increase to in excess of 1,000 beats per minute when flying, and a resting breathing rate of 245 breaths per minute. In terms of flight, they can hover, fly upside down, sideways, or backwards and forwards, with forward speeds of 25 to 30 miles an hour, and top speeds of 60 miles an hour in dives, with wings beating from 70 to 200 times per second. They are voracious feeders. The Black-chinned Hummingbird, for example, slurps nectar along two grooves in its tongue at a rate of 13-17 licks per second. Several species migrate very long distances, with most species wintering in Southern Mexico. The Rufous Hummingbird, for example, takes one of the longest migratory journeys of any bird in the world, covering 3,900 miles (one-way) from Mexico to Alaska and return in one season!
Later in the day, after the Black-chinned and the Rufous group has had their fill and left, a lone female Calliope Hummingbird is seen coming to the feeder for a long quiet slurp, all to herself … Calliope Hummingbirds are the second smallest hummingbird and are the smallest breeding bird in the U.S.
Hummingbirds are also very smart. Their brain comprises 4.2% of their body weight, which is reportedly the largest percentage in the bird kingdom. Human brains by contrast comprise only about 2% of their body weight. (A fact which offers a different take on the disparaging human epithet “bird brain”!)
Research on Rufous Hummingbirds has shown that hummingbirds possess elements of episodic-like memory, namely the concepts of where and when. Apparently, this memory enables them to remember not only where every feeder or flower is and when it will be refilled with nectar on a local basis, but also functions equally well for the entire migration route and from one year to the next. Our experience here at the Casitas also seems to agree with the reported claim that they quickly learn who fills the feeders and who doesn’t!
The average life span of hummingbirds is 5 years, however life spans of 10 years are documented for some species, such as the Black-chinned. Thus, it is likely that many of the hummingbirds visiting Casitas de Gila Guesthouses are repeat visitors and have been coming here for several generations.
Two members of the Brush-foot Family (Nymphalidae), a Common Buckeye (Junonia coenia) and a Bordered Patch (Chlosyne lacinia), enjoy the nectar of the Coreopsis flowers planted in the courtyard at the Casita Office.
BUTTERFLIES ABOUND AROUND BEAR CREEK CANYON
In August, about a month into the Monsoon Season, wildflowers peak both in number and diversity throughout the riverine forest that borders Bear Creek, 100 feet below Casitas de Gila Guesthouses. Accompanying the hummingbirds that gather to exploit this annual profusion of colorful blooms and fragrance are the Butterflies, flitting from flower to flower in silent, graceful counterpoint to the noisy, chaotic darting to and fro of their avian competitors.
New Mexico: Land of the Lepidoptera
It is estimated that there are about 20,000 species of butterflies in the world, with about 725 species reported from North America north of Mexico, of which about 575 species are found in the lower 48 states of the United States. Approximately 300 species of Butterflies (Class: Insecta; Order: Lepidoptera) are reported from New Mexico, representing one of the most diverse Butterfly faunas in the United States. This faunal diversity is due to the great geographic diversity of the immense New Mexico landscape which includes portions of the Great Plains, the Southern Rocky Mountains, the Basin and Range, the Colorado Plateau, the Sonoran and Chihuahuan Deserts and the Sierra Madre, with elevations ranging from 2,970 feet in the southern deserts to 13,039 feet in the northern mountains. About 100 species are known from Grant County where the Bear Creek Nature Preserve and Casitas de Gila are located.
Unidentified species of Skipper Family (Erynnis sp.?) (Hesperiidae) on Marigold flower in the Casita Office courtyard.
Common Checkered Skipper (Pyrgus communis) on Coreopsis flower
Northern Cloudywing Skipper (Thorybes phylades) on Butterfly Bush in the Office Courtyard
The Butterflies of New Mexico are classified scientifically as belonging to two Superfamilies: the Superfamily Hesperioidea, which includes a single family of Butterflies known as the Hesperiidae, commonly known as the Skipper Butterfles; and the Superfamily Papilionoidea, comprised of five separate families including the Papilionidae (Swallowtail Butterflies), the Pieridae (White or Sulfur Butterflies), the Nymphalidae (Brush-footed Butterflies), the Lycaenidae (Gossamer-Winged Butterflies or the Blue and Copper Butterflies), and the Riodinidae (Metalmark Butterflies). (Note: While these groupings, which are based on various distinctive physical features, seem rather complicated at first, if one studies photographs of representative species from each family, one quickly sees that the groupings are quite distinct in appearance from one another visually.)
A Painted Lady (Vanessa cardui), Brush-footed Family (Nymphalidae), feeds on a Zinnia in the Casita Office courtyard
A Varigated Fritillary (Euptoieta claudia), Brush-footed Family, slurps up nectar from a Marigold flower in the Casita Office courtyard
A Gulf Fritillary (Agraulis vanillae), Brush-footed Family, enjoys the Marigolds in the Casita Office Courtyard as well
A Queen Butterfly (Danaus gilippus), Brush-footed Family, forages on a Seep Willlow flower (Baccharis salicifolia) below the Casitas on Bear Creek. The Queen Butterfly is in the same Genus as the famed Monarch (Danaus plexippus), but does not make the legendary migration to Mexico that the Monarch makes.
Over the years, numerous species of butterflies have been observed at Casitas de Gila, both those feeding on the wildflowers along Bear Creek, as well as species attracted to the native plants and non-native flowering plants brought in for landscaping around the Casitas. In the Spring of 2014 an extensive planting of various traditional garden flowers was undertaken in the courtyard at the Casita Office. Beginning in late July and peaking in early August, a large variety of butterflies were swarming the courtyard flowers daily. It was a spectacular sight, delighting both the Casita hosts as well as incoming guests. Then, by the middle of August, although the flowers were still at the height of their blooming, the number and variety of butterflies suddenly plummeted as a series of cold nights occurred following evening thunderstorms. Within a matter of a couple of days, the spectacular butterfly pageant was over, only to be replaced, to the head gardener’s horror, by a vast horde of thousands of tiny, half-inch grasshoppers that immediately set upon devouring every flowering plant in sight.
A Sleepy Orange (Eurema nicippe), Whites and Sulphurs Family (Pieridae), slurps nectar from a Zinnia in the Casita Office courtyard.
A Southern Dogface (Zerene cesonia), Whites and Sulphurs Family, drains the nectar from a Butterfly Bush flower in the Casita Office courtyard.
A Checkered White (Pontia protodice), Whites and Sulphurs Family, slurping nectar from a Trailing Windmills flower (Allionia incarnata) below the Casitas along Bear Creek
Cycles of Natural Change Affect Butterfly Diversity and Abundance in the High Desert
The diversity and abundance of flowers along Bear Creek and adjacent lands varies significantly from year to year. The dominant controlling factor, of course, is precipitation—when and how much. After 15 years of observation, here at the Casitas about all that is certain is that no 2 years are alike in terms of when, where, and how much rain will fall during the Summer Monsoons along the Bear Creek drainage system, and, consequently, whether a particular flower species will be abundant or not. Not surprisingly, the butterfly species, both in terms of diversity and abundance, also show similar variation and unpredictability from year to year.
Temperature variations are much less a factor than precipitation in affecting diversity and abundance of various species, but in some years, such as this year, it can be significant. The Summer of 2013, was a bountiful year for both wildflowers and butterflies. The Monsoon rains started right on schedule with a major hail and rain thunderstorm on July 2, and continued into the third week of September, triggering 7 major flash floods along Bear Creek, with extensive flooding across the entire floodplain lasting up to several hours and running several feet deep. Temperatures were normally warm throughout the period especially during August, the peak month for flowering.
Summer 2014 has been a different story, however. Overall, temperatures have been cooler, especially during August, which has seen more cloud cover, and atypical slow drizzling rains of minor accumulation instead of the more typical heavy downpours resulting from intense, but short-lived thunderstorms. Many nights have been exceptionally cool, in the high 50s F, as evidenced by numerous cottonwoods showing extensive premature yellowing of the leaves. Also, very little rain has fallen during the second half of the month. A similar weather pattern has existed during the month throughout the 25 mile-long Bear Creek drainage basin as evidenced by the fact that the Creek has not yet experienced a single major flash flood this year. The stock fences across the Creek at the north and south ends of the Casita property, which are normally washed away several times each summer, are still standing, having been put up at the end of the Monsoon Season last year. By the middle of August, flowers along the Creek were still not blooming in abundance and many plants were starting to wither. As observed in the Office courtyard, butterfly diversity and abundance along the Creek peaked in early August and dropped off markedly after the middle of the month, with only a few species and numbers remaining. All in all it has been an unusual Summer, well illustrating the amazing Cycles of Natural Change that occur in this High Desert landscape.
These Iconic Plants of Southern New Mexico Were
Nature’s Grocery Store, Pharmacy, Fabric Shop, and Hardware Store
for the Native Americans of Southwest New Mexico
Soaptree Yucca at Casitas de Gila Guesthouses
Beargrass along Turkey Creek Road in the Gila National Forest
Sotol along Turkey Creek Road in the Gila National Forest
SHOWTIME IN THE HIGH CHIHUAHUAN DESERT
Soaptree Yucca outside the Gallery
Sotol along the road approaching the Casitas
Beginning sometime in June, and generally peaking in early July, the Juniper and Piñon dominated High Chihuahuan Desert landscape surrounding Casitas de Gila Guesthouses often delights our guests with an extravagant Welcome-to-Summer white and golden flowering of the ubiquitous Yucca, Sotol, and Beargrass plants that thrive across this arid terrain. The magnitude of the flowering is a function of several factors, but primarily reflects the amount and timing of the previous Winter and Spring precipitation.
It was obvious that all of the various factors were optimum over this past Winter and Spring because this year’s display was simply magnificent! No matter where one looked, the brilliant white flowering plumes of the Soaptree Yucca (Yucca elata) atop their 6-to-12 foot stalks, and the golden plumes crowning the soaring 10-to-16 foot stalks of the Sotol (Dasylirion wheeleri) could be seen in glorious contrast against the deep green of the Juniper trees or the cobalt blue of the New Mexican sky.
THE DESERT YUCCA
Soaptree Yucca along the Nature Trail at the Casitas
Flowers of the Soaptree Yucca at various stages of blossoming
In 1927 the New Mexico Legislature established the blossom of the desert Yucca plant as the State flower. Only the Genus was specified, allowing the designation to apply to the several species of the plant growing within the State. Early settlers referred to these lovely flowers, which are found in all sectors of New Mexico, as “Our Lord’s candles” — “las lamparas de Dios” or the lamps of God. A magnificent flower at any time, for many it is when viewed on a full moon night, when the snow white plumes appear to float suspended in space high above the desert floor, that the ethereal beauty of the bloom is best appreciated.
There are some 40 to 50 species of Yuccas in the Americas and the Caribbean, all of which share the common characteristics of a basal, rosette, or circular arrangement of sword-shaped leaves and clusters of white or whitish flowers set at the top of a tall stem or stalk. Here at the Casitas there are two species of Yucca: the abundant Soaptree Yucca (Yucca elata) and the much less common Banana Yucca (Yucca baccata).
Soaptree Yucca along the road at the Casitas that’s bent by the strong prevailing west winds.
The Soaptree Yucca (Yucca elata) has narrow, 0.25 inch, sword-shaped leaves 1 to 3 feet long, with needle-sharp tips, and grows to heights of 15 feet or more with a small diameter, occasionally branching, cylindrical trunk that is generally covered with a dense mat of dead leaves. Following the flowering phase, which consists of an inflorescence of large 1.25 to 2.25 inch bell-shaped flowers, the fruit appears in the form of numerous, large, three-chambered seed pods or capsules, two to three inches long and an inch in diameter. Each of these chambers contains two poker-chip-like stacks of flat black seeds. Eventually these pods dry and crack open, releasing the seeds to be spread by wind, surface water runoff, birds and animals. Various insects love the nectar of the Soaptree Yucca, but the flower is only pollinated by a species of the Yucca Moth.
Honeybees love Soaptree Yucca flowers but do not pollinate them.
The fruit of the Soaptree Yucca is a three-chambered pod or capsule.
Opened Soaptree Yucca seed pod showing three-chambered structure.
Flowering Banana Yucca near the Gallery at the Casitas.
The Banana Yucca (Yucca baccata) grows close to the ground, with only a short trunk, if present at all. The sword-shaped leaves are 1.25 to 1.5 inches wide, up to 3.5 feet long, with curled fibers along the margins, and needle-sharp tips. Height of the plant, including both the leaves and flower stalk rarely exceeds 4 or 5 feet high. While the flowers of the Soaptree Yucca and Banana Yucca are similar, their fruits are quite different. Unlike the more woody, tough, chambered seed pods or capsules of the Soaptree Yucca fruits, the Banana Yucca fruits are large, 3 to 6 inches long and 2.5 inches thick, fleshy, and soft and sweet when ripe. As a result they are much sought after as a food source by insects, birds, animals, and humans. Rarely do they reach ripening stage on the plant before being eaten. Like the Soaptree Yucca, the Banana Yucca is pollinated by a species of the Yucca Moth.
THE YUCCA AND THE YUCCA MOTH: A 30-50 MILLION YEAR OLD ROMANCE
Yuccas and Yucca Moths have been enjoying a romantic relationship for some 30 to 50 million years now. What has kept them together all those years makes for an interesting love story in intra-specifc relationships . . .
Seed pod of Soaptree Yucca showing hole where Yucca Moth larvae bored out prior to the drying out and splitting open of the seed pod.
Yuccas reproduce by seeds produced from the pollination of the flowers. The flowers of Yucca plants are pollinated by three genera of the family of moths known as Prodoxidae. Certain species of two of these moth genera, the Tegeticula and the Parategeticula, have what is called an obligate pollination mutualism arrangement with particular species of Yucca. What this means is that certain species of Yucca are only pollinated by a particular species of Yucca Moth, an evolutionary development in which both species are mutually benefited, which, in this case, is by successful reproduction.
For the Soaptree Yucca the mutualistic Yucca Moth is Tegeticula yuccasella1. In this torrid relationship, the female moth first deposits an egg in the flower’s ovary, after which, in a display of impassioned gratitude, she collects a large ball of pollen from the flower, two or three times the size of her head, and then inserts it into the stigma of the flower! After a week or so the egg hatches there and the baby moth larvae will munch on some of the seeds developing from the ovules. After a few weeks, the seed capsules begin to open, at which time the mature larvae now bores its way out of the capsule and tumbles to the ground where it bores down into the ground, forms a silken cocoon, and begins a long winter’s nap while waiting for next season’s Yucca flowers, at which time it will complete the cycle and emerge from the ground as a new Yucca Moth!
The Banana Yucca and the Yucca Moth also have a obligate pollination mutualism relationship in which the romantic modus operandi of the moth, Tegeticula baccatella, is essentially the same as that of Tegeticula yuccasella.
MODERN USE OF YUCCA
Dried Soaptree Yucca stalks are strong and light, a perfect combination for the handcrafted walking sticks made by Jeff Ross for the Gallery at Casitas de Gila.
Today, all species of New Mexican Yucca are extensively used in xeriscaping because of their extremely low water requirements and their iconic Southwestern beauty. They are easy to grow and once established require virtually no maintenance.
The flower stalks of the Yucca are extremely strong and light, therefore they make excellent walking or hiking sticks. Here at the Casitas we provide them as walking sticks, and also use and decorate them as a Christmas tree in each Casita. Compared with other natural woods, Yucca as well as Sotol stalks have an exceptionally low ignition temperature. Consequently, they are excellent as drill and hearth or fireboard material for outdoor primitive friction fire starting using the plough, handrill or bow techniques as used by hunters, campers and practitioners of wilderness survival skills.
The use of Yucca as well as Sotol stalks in various types of building construction was widely practiced by both Anglo and Hispanic settlers in the traditional architecture of the Southwest, from crude enclosures of various kinds to the unique latillas over vigas in room ceiling construction. Modern construction of traditional architecture continues such use.
Sotol (Dasylirion wheeleri) is a common flowering plant of the arid Southwest found in both the Sonoran and Chihuahuan Deserts. At first glance the plant can be mistaken for a Soaptree Yucca with its rosette or globe-shaped mass of 0.50 to 1 inch wide and 1 to 3 foot long sword shaped leaves radiating in all directions at the top of a short, 5 foot or less, brown unbranched trunk cloaked in dead leaves. Looking closer, however, one quickly sees or perhaps is unfortunate enough to feel that the leaves have dangerously sharp barbs or saw-tooth spines lining the leaf margins.
Sotol replace the Soaptree Yucca above 5,000 feet elevation at the Casitas, and here along Turkey Creek road in the Gila National Forest.
A phalanx of Sotol plants marching south down the mountainside along Turkey Creek Road in the Gila National Forest.
Close up of flowering inflorescence of Sotol along the road into the Casitas. Honey Bee shows size of individual flowers!
MODERN USE OF SOTOL
In the U.S. the Sotol plant is often used for xeriscaping like the Yucca, although its flower is less showy and and saw-tooth barbs on the leaves render it less friendly or desirable in gardens. The woody flower stalks are strong and light like the Yucca and are frequently handcrafted into walking and hiking sticks, and some practitioners of friction fire starting prefer Sotol over Yucca as a hearth or drill material.
In Northern Mexico, mostly in the region of Chihuahua, however, Sotol is wild-harvested on a commercial scale where the hearts of the crown are baked, femented, and double-distilled to make a spirit liquor that is somewhat similar to tequila and mezcal.
Beargrass (Nolina microcarpa) can be considered a distant relative of both Yucca and Sotol in that all three belong to the family of flowering plants known as the Asparagaceae, of which the namesake Genus Asparagus belongs, as well as our favorite Spring vegetable species, Asparagus officinalis.
Plumes of flowering Beargrass catching the early morning Sun along Casita Flats Road.
Clump of Beargrass. Fibers from the long, narrow leaves were used extensively by all cultures of Native Americans for cordage, basketry, and woven mats of all types.
Many Native American cultures used flowering Beargrass for food, eating the emerging young flower stalks, the small fruit that followed the flowering, as well as the seeds that developed within the fruit.
Beargrass is widely spread over the American Southwest and Northern Mexico. Its growth form is that of a globular clump of narrow, 0.50 inch, coarse, thick, wiry, and serrated grass-like leaves up to 4 feet long with dry, curled and string-like tips. It grows in a variety of habitats from desert grasslands to juniper and piñon woodlands, and especially in overgrazed ranch land where the plant can attain dense concentrations with individual plant diameters of 6 feet and a height of 4 to 5 feet.
Beargrass has no above ground stem or stalk, but rather an underground woody caudex from which the leaves and flower stalks grow. Like the Yucca and the Sotol at the time of flowering it puts up a stem or stalk 4 to 6 feet tall, at the top of which is found a much-branched inflorescence of tiny white flowers, 0.10 inch, which produce small green fruits and eventually encapsulated seeds.
MODERN USE OF BEARGRASS
Beargrass is another southwestern plant mostly used in xeriscaping, particularly as an accent, in borders, and in stabilizing hillsides.
Clumps of Beargrass at the top of Telephone Mountain near the Casitas, looking northeast to the Mogollon Mountains in the Gila Wilderness.
NATIVE AMERICAN USE OF YUCCA, SOTOL AND BEARGRASS
Various species of Yucca, Sotol and Beargrass were widely used by all cultures of Southwestern Native American Cultures from pre-historic to historic times. These three plants were extremely important to these cultures, serving as Nature’s grocery store, pharmacy, fabric shop, and hardware store in those times. Many of these uses and customs are still practiced today.
The following categories, uses and practicing cultures are documented in the University of Michigan at Dearborn Ethnobotany Database.2
Soaptree Yucca (Yucca elata)
Peeled stalk shaped like a short snake eaten by a practitioner and spit at the sick (Apache)
Flowers boiled and eaten as vegetable, added to soups, or dried for later use. (Apache)
Trunks baked overnight in rock-lined pits and dried in pieces for later consumption after softening in water (Apache)
Trunks pit cooked, dried, and pounded into flour (Apache)
Young flower stalks cooked, peeled, and eaten hot (Apache)
Flower stalk charred and eaten like sugar cane (Apache)
Leaves woven into shallow baskets or trays for carrying things (Apache)
Leaves used as the binding element in coarse coiled ware (Papago)
Red roots used as basket decorations (Apache)
Fiber Cordage (ropes, string, binding material)
Leaves used to make cordage (Apache)
Leaves tied to make a fastening loop for sandals (Southwest Native Americans)
Leaves used for the headshade of cradleboards (Apache)
Fiber Building Material
Used for weft (horizontal lashing) in house frames (Papago)
Fiber Sewing Material
Thread-like fibers from pounded leaves used to sew fiber coils into tight baskets (Papago)
Thread-like fibers woven into nets for carrying things (Pima)
Fiber Mats, Rugs and Bedding
Leaves woven into mats (Pima)
Roots used for making soap (Apache, Pima, Navajo)
Banana Yucca (Yucca baccata)
Dermatological aid for washing hair (Keresan Pueblo, Apache)
Infusion of pulverized leaves remedy for vomiting, heartburn (Navajo)
Fruits eaten raw as as a purgative or laxative (Pima)
Unspecified parts chewed as emetic to induce vomiting (Tewa)
Fruit eaten to promote easy childbirth (Tewa)
Dried fruits dissolved in water for beverage (Acoma Pueblo, Papago)
Fruit used to make a fermented beverage (Hualapai)
Fruits eaten raw, baked or boiled, or dried, made into cakes or rolls, and stored for future or winter use (Acoma Pueblo, Keresan Pueblo, Apache, Havasupai, Hopi, Hualapai, Navajo, Papago, Pima, Zuni)
Ripe fruits dried, ground, made into cakes and roasted (Navajo)
Ground dried fruit cooked with cornmeal to make gruel (Navajo)
Dried fruits eaten as a preserve or dissolved in water and used as a dip (Acoma Pueblo, Hopi, Navajo, Zuni)
Fruits made into a syrup (Keresan Pueblo, Apache, Zuni)
Tender crowns roasted and eaten in times of food shortage (Acoma Pueblo, Laguna Pueblo)
Young leaves cooked in soups with meat (Apache)
Flowers eaten before summer rains (Apache)
Pods roasted and eaten or dried for future use (Apache)
Seeds dried and eaten (Papago)
Flower stalks gathered before blossoming, roasted in fire and eaten (Yavapai)
Dyes, Pigments, Painting
Leaf juice used as medium for pigments of pottery paints and slips (Navajo)
Brushes and Brooms
Leaf fibers used to make small brushes for pottery decoration (Isleta Pueblo, Navajo)
Leaf fibers made into brushes for cleaning baskets (Navajo, Yavapai)
Leaf fibers made into hair brushes (Pima)
Leaves woven into baskets (Apache, Hop, Isleta Pueblo, Jemez Pueblo, Papago, Pima, Zuni)
Small red roots used as basket decorations (Apache)
Fiber Cordage (ropes, string, binding material)
Leaves used to make rope or twine (Apache, Havasupai, Hualapai. Isleta Pueblo, Navajo, Pima, Tewa, Zuni)
Leaves reduced to fiber and made into cloth (Apache, Zuni)
Stems (trunks?) used to make shoes (Hualapai)
Fiber Building Material
Used for weft (horizontal lashing) in house frames (Papago)
Fiber Sewing Material
Terminal spines used as needles (Havasupai)
Thread-like fibers woven into fishing nets (Tewa)
Fiber Mats, Rugs, Pads and Bedding
Leaves woven into mats to cover various openings and vessels (Zuni)
Leaves woven into water jug-carrying head pads (Zuni)
Crushed leaves mixed with water for soap (Keresan Pueblo, Pima, Papago)
Roots pounded and placed in water for suds for bathing and shampooing or soap (Apache, Havasupai, Hopi, Hualapai, Navajo, Zuni)
Fire Starting Material
Thick portion of flower stalk used as hearth for friction fire making (Apache)
Stalk used to make fire drills (Apache)
Sotol (Dasylirion wheeleri)
Crown of plant pit-baked, peeled, crushed, mixed with water, fermented, and drunk as beverage (Apache)
Crown of plant pounded and used as drink (Apache)
Crown of plant baked in pit, stripped, pounded to a pulp, dried, and eaten like cake (Apache)
Crown of plant pit-baked, dried, pounded into flour, and made into cakes (Southwest Indians)
Flower stalks roasted, boiled, or eaten raw as greens (Apache, Papago)
Flower stalks boiled, dried, and stored for use as vegetables (Apache)
Head (crown) hearts cooked with bones as soup (Apache)
Flower stalks used as cross pieces for cradleboard backs (Apache)
Leaves used in coiled basketry (Papago)
Leaves used to make headbands and headrings (Papago)
Stalks used in the head dress of Mountain Spirit dancers (Apache)
Fiber Mats, Rugs, Pads and Bedding
Leaves woven into mats (Papago, Pima)
Leaves used to make large sleeping mats, cradle mats, and back mats for the carrying frame (Papago)
Fire Starting Material
Stalks dried, split, drilled to make small holes and used as fire drill hearths (Apache)
Beargrass (Nolina microcarpa)
Decoction of root taken for rheumatism (Isleta Pueblo)
Decoction of root taken for pneumonia and lung hemorrhages (Isleta Pueblo)
Flower stalks roasted, boiled, eaten raw, or dried and stored for use as vegetables (Apache)
Seeds made into a meal and used to make bread (Isleta Pueblo)
Seeds used to make flour (Isleta Food)
Fruit eaten fresh or preserved (Isleta Pueblo)
Seeds made into a meal and used to make mush (porridge) (Isleta Pueblo)
Dyes, Pigments, Painting
Plant used to make a dye for blankets (Navajo)
Brushes and Brooms
Leaf fibers used to make brushes (Isleta Pueblo)
Leaves woven into baskets (Keresan Pueblo, Isleta Pueblo, Jemez Pueblo, Papago, Southwest Native Americans)
Leaves used to make baskets for storage and washing of grains (Jemez Pueblo)
Leaves used as the foundation in coiled basketry (Papago, Pima, Southwest Native Americans)
Fiber Cordage (ropes, string, binding material)
Leaf fibers used to make cords, ropes and whips (Isleta Pueblo)
Leaves used as tying material (Southwest Native Americans)
Fiber Mats, Rugs, Pads and Bedding
Leaves used to make mats (Keresan Pueblo)
Leaves woven into a coarse mat and used for drying mescal (Havasupai)
Leaves used as a dwelling ground covering (Apache)
Leaves used as a thatching material for wickiup or ramada (Apache)
Leaves used for thatch (Havasupai, Yavapai)
Leaves used to make matting to cover the dead (Southwest Native Americans)
Leaves woven to trays for procesing datil (Banana Yucca) and mescal (Apache)
Leaves used as wrapping material for foods to be transported or stored (Apache)
Roots used as soap (Apache)
Fire Starting Material
Thick portion of flower stalk used as hearth for friction fire making (Apache)
Stalk used to make fire drills (Apache)
1. Craig D. James, et. al., 1993, Pollination ecology of Yucca elata, Oecologia, Vol. 93, No. 4
2. University of Michigan at Dearborn Ethnobotany Database