Below: Tres Alamos Wash (North of Benson), viewed from a point close to the "Grand Bridge" of Cascabel Road near milepost 5, looking West towards the River confluence (July 2002):

In the image above, the very broad floodplain of Tres Alamos Wash runs from near lower-right to mid-left of the photo, then bends sharply rightward against the terrace which slants across the photo from above-mid-left to the upper center of our view. (This terrace formation also dates from the time of the St. David Formation Lake of the Pliocene period). At the far end of the terrace, you can see a short horizontal strip of pale green, marking irrigated farmlands located on the San Pedro River floodplain. Click on the image above for a better view of the terrace-and-confluence area. Behind the floodplain rise a line of comparable terraces flanking the far side of the River, then the Little Rincon Mountains, and behind them, Rincon Peak. Just upstream from and out of view to the left of the terrace formation just discussed, the Ash Creek runs into the San Pedro from its source in Rincon Peak (at the top center horizon in the photo), while a short distance downstream from the irrigated farmlands the River begins its bend in a northeastward direction.

This map below shows how the Cascabel Road bisects the Tres Alamos Wash toward the right of the image. Note the unusually arrow-straight line of the road along this stretch. At the far left of the map you can make out the Ocotillo Road, which extends north from Benson along the West side of the River.

In the late 1980s, the Cascabel Road was a dirt road where it crossed the Tres Alamos Wash, but incongruously it contained these very large road cuts shown below, associated with the large and rather expensive bridge which had been built across the Tres Alamos Wash. These images show, at left, a view of the bridge, arrow-straight road and the two grand cuts taken from the north; at center, the southermost cut viewed from the south end of the construction zone (the existing Cascabel Road enters the cut from the middle-left of the photo, turning sharply into the cut as you go north; at right, a view from the north looking toward the projected road's southern direction, which until recently had a sign proclaiming "Road Closed" (now only a remnant remains). (Photos taken in March 2004.) (Click on each image to enlarge it.)

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Since beyond this sign toward the south the land drops away abruptly in a series of deep ravines running perpendicular to the apparent target of the road -- U.S. Highway I-10 some 7 miles to the south -- the prospect of building a road further in that direction would seem very daunting indeed (not to mention that of cutting similar gashes through the various lands further north). One story (not confirmed) relates that in the late 1970s some members of the Arizona Department of Transportation Board pushed this project (as State Road 76) through, aiming to provide a route from I-10 to Phoenix which would bypass Tucson, but the effort ended after three bridges had been built and some Right-of-Ways had been purchased. The project apparently foundered in conflicts over funding and with recognition of the ruinous costs that would be incurred for its completion. (Some topo maps appear to outline the projected road extension to I-10, running in a straight line toward the south-southeast.) In any case, we owe the present relative wildness of the Cascabel portion of the San Pedro River Basin to the fact that the project was not completed at that time, since a road of this investment caliber would surely have been paved, and Cascabel by now would be a bedroom suburb of Tucson.

Beyond these cuts, the road turns north-north-westward as you go downstream and drop down toward the River. In March 2005, the gray hills of the Little Rincons foothills which approach the River at this point were covered with Spring Poppy blooms:

Below: see the Narrows -- or the "Benson Narrows", to distinguish it from the Narrows further downstream near Redington (see further below, the "Redington Narrows"). This Narrows (note the distinct rock-outcrop "edges" at both left and right) marks a geological (and to some extent at least hydrological) boundary between the upstream portion of the River and the part located further downstream. These two images are from August 2002 (left) and January 2005 (right), both looking downstream through the Narrows from viewpoints just east of the Cascabel Road. In both images, Bassett Peak of the Galiuro Mountains is framed in the distant background --near the center horizon in the left image, and well to the right in the right image. In the left-hand view, taken from further upstream, Sierra Blanca is just visible in reddish brown behind the left edge of the Narrows, while in the right-hand view the image is pointed in a more northerly direction and is taken from a slightly higher hill. Click on each image for a closer view of the Narrows gap and the valley-&-Sky Island country beyond:

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Below, a view of the Narrows from the downstream side looking toward the southwest.

Note in the image above the riparian tree in the lower left.

Over a four-mile stretch of the River straddling the Narrows, the riverbed drops about 40 feet, a hydrological change where deep valley fill upstream meets this bedrock outcrop that forces water to the surface. Early 19th-century explorers reported that at this point the then-perennial stream spread out widely to the north below the gorge, forming sporadically extensive swamps containing beaver dams, running all the way past Cascabel.

Below, a map of the Narrows showing its location relative to the Cascabel Road. The rock formations that straddle the Narrows are ancient (structurally similar to those of the Johnny Lyon Hills, see below), but those bounding the roadway are much more recent, lakebed formations connected with the Pliocene St. David Formation further south.

Below, a view across the Benson Narrows looking west. The lip of the Narrows is in the near foreground, Wildhorse Mountain in the distant far right.

Below left, a view in October 2007 from the lip of the Narrows looking upstream. Standing water is visible in the lower left quadrant of the image. (Click on the image for a better view of the water.) Below right, from the lip looking downstream, the wash is entirely dry at this time. The Gaging station is visible in mid-photo. (Click on the image for a closeup.)

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Below: the visually striking Johnny Lyon Hills rise above the San Pedro east of where it runs through the Narrows. These formations (which extend to the Narrows) are composed of the geologically oldest rocks in our area, uplifted granodiorate formations that are 1.65 Billion years old (see Age of the Earth). The image at left was taken in January 1999 from the west side of the River, the one on the right in March 2005 from the 3-links Road well to the east of the River. (Click on each image for enlarged views.)

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(Long-time Cascabel resident Barbara Clark has heard a story that these hills were named after an early mining
claim/homesteader who lived in the area. Not much seems otherwise known about him, but his name lives on by virtue of these very memorable hills.)

Below: Fremont Cottonwood/Goodding Willow Gallery Forest marks the zig-zag San Pedro River channel near the 3-Links Farm near Milepost 13 (October 2002): (Click on the image to enlarge it)

Below: at the 3-Links Farm, the river becomes a perennial flow for a considerable stretch (cattle have been fenced off the immediate floodplain here for many years). When this picture was taken in February 2003, Dace were spawning in the streambed. Here we're looking upstream. (Click on the image for a close-up from the right bank.) (Close-up taken in April 2005)

Recently, The Nature Conservancy bought this 3-Links part of the River, and ceased the agricultural pumping of river water (formerly done to grow alfalfa), and over several years the perennial stream has expanded more than a mile in length (though this varies depending on drought intensity).

For more information and images showing the biological richness of the River along this 3-links stretch, see this link: The Nature Conservancy 3-Links Tour, April 2005.

Near Milepost 16, a series of hanging Quiburis-era terraces flank the west bank of the River:

Below, near Kelsey Wash at Milepost 17, a much older series of pale misty-rose-colored vertical cliffs also flank the River. Judging from the geology map in Dickinson 1991, the vertical cliffs in this image are also members of the Quiburis Formation. (Click on the image for a close-up view.) (The hills rising above and behind them, however, are "Metamorphosed Paleozoic Strata".)

Below, looking down on the same cliffs (at lower right) from the Pool Wash Ridge Road near Sierra Blanca, a vantage point about 600 feet in altitude above the River. The Quiburis Formation cliffs shown just above stand out prominently at lower middle-right, while the Three Links flats are the green area at far middle-left of the photo. (Huachuca Mountains at far upper left toward the south, Whetstones the dark blue mountains at right-middle.)

Teran Wash drains a large basin lying eastward and southeastward from milepost 20. The extensive Teran-Kelsey Escarpment bounds this basin on the southeast side:

Like the other portions of the West Range of the Galiuro Mountains bounding the San Pedro River in this area, the Teran-Kelsey Escarpment shows strong block-fault tilting away from the River Valley. For more detailed views of this piece of the Galiuros, see this link: Teran-Kelsey Escarpment, and for geological context see Geology Walk: 3) Basin-Range Faulting.

Many washes that cross the Cascabel Road present serious danger to traffic during and after rainstorms. Below, after a storm in late July 2005, Kelsey Wash runs moderately. In this example, careful examination indicated the Wash was safe to cross for the high-centered, 4wd vehicle parked here. However, the Kelsey Wash is notorious for carrying down substantial boulders when it runs more strongly than this, and becomes too dangerous to cross. Usually the strong pulses are fairly brief. (For the likely old-historical significance of Kelsey Wash, see An Ancient Native American Trail.)

Along many parts of the River basin in our area, severe downcutting of the river's channel has occurred, a process which accelerated along the river during and after the 1890s drought (see discussion of this process in San Pedro Changes). For example, a difference from the early years of this century has been noticeable near the Teran Wash confluence, where one side of a downcut channel is shown below: (in July of 2006)

The channel here is about 20 feet deep, with the old pre-20th century floodplain (with its mesquite bosque) at the top of the embankment. Below, a March 2007 view from the edge of the mesquite bosque looking down into the River at this point:

Note the precariously situated mesquite tree at left-center of the photo. Below, vivid evidence of the continuous loss of this bosque to riverbank erosion:

Long-term resident Barbara Clark has old maps of the Teran Wash confluence from early in the 20th century, showing that Teran Wash apparently entered the River at the grade of the bosque at that time, so this marks a very considerable recent change. Some 6 miles further downstream from this point, however, perennial stream does reappear in places, and there the riverbed is not so channelized. Entrenchment is a prominent but not continuous feature of the River in our area.

Below, Teran Wash is marked by the 4-WD grazing-lease road running from upper-right to left-center of the map. As you can see, it is a wide wash, and formerly created a quite substantial delta prior to its down-cutting near the confluence.

Below: near the Teran Wash-confluence location, but from across the wash and further upstream, a view of the river in strong flood, August 2005:

Visitors who want to walk along this river wash should be aware of the weather conditions concerning rainfall for the day prior to the time they choose to do so. For example, on the morning of July 27, 2006, at 7:30 AM we walked down to the banks of the San Pedro River Wash near the Teran Wash confluence, to see the situation shown below left -- the Wash had run quite high recently, and the ground was very muddy, but there was no running water. The pool at middle right in the left-hand photo was standing water, in which two children rushed out to play, getting thoroughly covered with very sticky mud. However, we knew it had rained during the night, including around our location, so we had consulted the Saguaro Juniper website Weather & Climate page, going to "Quick Weather References: Our Current Weather Conditions", then scrolling down to the link which says "San Pedro River Current Flow near Redington, Benson, Charleston, or Palominas" and looked at the map showing current river flow at all of the sites upstream from us. We could see that a substantial flood pulse had begun at Palominas about 3 AM, and at Charleston a very substantial pulse rising up at about 2 AM. Benson showed nothing at 7 AM, but still we looked upstream a bit anxiously as we stood at the river bank while the children played in the mud for a few minutes. When we later returned to a point near the same location at about 11:30 AM, we could hear the sound of the River from a considerable distance away, and when we reached the lower bank took the photograph below right at 11:47 AM. (Click on each image for enlarged views.)

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The picture above right was taken near the Tamarisk Tree which is visible on the left in the image above left. While this was only a moderate flow of the River, it was running very fast in the main channel, with numerous mesquite logs and even tree-trunks being carried downstream, the rushing water probably about 10 feet deep at the central part. Note the dark material flowing in the more slow-running side-stream near the viewer at right -- this is transported organic duff, also coming from mesquite bosques being downcut along the banks upstream. When really strong floods hit this location, the water may reach some 20 feet in depth.

It's worth emphasizing the special danger of this river during the summer Monsoons, since anyone caught standing in the wash-bottom by a flash-flood of any size would probably be killed. See below an example of a very large animal, photographed at this same location after a similar flood occurred earlier in the month: (Click on the image to enlarge it.)

Below, at the same location but up on the old floodplain, the mesquite bosque was carpeted with London Rocket (an exotic species) in March of 2005, following good spring rains:

At some points along the River in this area, some geologic facies of the San Manuel Formation rise behind the bosque on the West side of the River, occasionally forming erosional flumes of striking beauty.

Below: just upstream from the confluence of Paige Wash with the San Pedro, some remarkable gray sedimentary hills (these terrace formations are of Quiburis age -- 7.5 to 5.5 Million Years old) erode down toward the river in many fingers:

These rapidly-eroding "badlands" provide many a cleft/flume refuge for nesting birds of various kinds. (Click on the above image for a close-up view.)

Below: Lower Hot Springs Canyon Wash and its mesquite bosque, running westward (lower left to middle-right in the image) toward its confluence with the San Pedro in the middle distance, July 2002. The bosque-scouring floods of October 1983 and January of 1991 and 1993 have left their marks here in the lighter-colored portions of the floodplain. Previously most of that open ground was thick bosque.) (click on image below for a larger view.)

Below: a view from the Quiburis Terrace (middle left in the photo above) looking across lower Hot Springs Canyon at the bosque that mostly fills the floodplain. (April 23, 2008)

Below, the bosque viewed from the first terrace above floodplain, in late afternoon sun (5:32 pm, April 23, 2008). (click on image below for a larger view)

Below: The confluence of Hot Springs Canyon Wash (foreground gallery forest) with the San Pedro River (the River wash cut can be seen running horizontally at right central) and Paige Wash (its bosque just visible beyond the left-central ridge terrace at dead center in the photo) -- Rincon Peak in the right background, Little Rincons dominate the mid-distance: (May 2002) (click on image below for a larger view)

Below, another view of this triple confluence from higher up on the east bank terrace of lower Hot Springs Canyon. (Note that the saguaro fruits are ripe on this day, June 30, 2002. This would have been a great day for saguaro fruit harvesting.) Here the San Pedro River gallery forest shows in a horizontal green strip running from just to the right of the left-hand cluster of Saguaros, while Paige Canyon's bosque shows more clearly beyond the horizontal terrace at dead center of the photo. Paige Wash cuts back across the base of the strong, high ridge that dominates the upper left portion of the photo at mid-distance, then runs to its confluence at far right mid-photo. Hot Springs Canyon confluence is just to the left of it. (click on image below for a larger view)

In the map below, Hot Springs Canyon drops into the San Pedro River where the right-hand "Cascabel" logo is placed. (The road trail shown running northward beside it, incidently, no longer exists.) The Paige Canyon Wash enters the River just upstream from it, coming from the south in the lower left quadrant of the map. Pool Wash enters the River about a mile further upstream.

See this link for more details on Hot Springs Canyon. At this location, the volcanic fault-block-tilted escarpment of the Galiuro Mountains parallels the San Pedro Valley along its eastern side: (see that link for many more images and maps of this, the wildest mountain range in southeastern Arizona)

Where the Cascabel Road crosses the Hot Springs Canyon, below, the substantial rains of July 2006 produced a heavy stream flow photographed here by Susan Newman on July 29, looking southward. Although the roadway has a belt of concrete surfacing that runs from side to side to stabilize the crossing at this very large Wash, these vehicles are prudently waiting for the pulse to decline further. The strip of rocky alluvium sitting across the roadway shows that the previous flow was much stronger than what you see here. (Click on the image for a closer view.)

The notes of caution stated above were not idle comments. On the night of August 07, 2006, a pickup truck pulling a trailer full of hay sped southward on Cascabel Road past the houses at Helfrich's ranch and tried to cross the Hot Springs Canyon Wash. Although no rain had fallen along the roadway that day, a very heavy downpour had occurred earlier in the evening far upstream near the Muleshoe Preserve , and the Wash was now running in a strong flood across the road. The truck's trailer was pulled downstream off the concrete by the water and the truck, dragged after it, stopped with only one truck wheel remaining on the track while the waters roared around it. One of the riders fell out immediately into the flow, while the other stood on a strawbale in the trailer. Drivers stopped at the scene saw the situation and tried to throw the man a rope, but he lost his balance and was also swept away. One body was recovered a short distance downstream and the other well downstream along the San Pedro Riverbank. Sue Newman, who lives nearby and made the 911 call that brought the police, reports that after the flood subsided the officers found that the vehicle's engine was still running, so had the two men stayed inside it they would have been saved.

In November 2006 this memorial shrine could be seen on the northwest side of the Wash crossing (looking north). (Click on the image for a closer view.)

In February 2007 another memorial was located a short distance further north (downstream): (Click on the image for a closer view.)

From this location at the roadside, the view of Lower Hot Springs Canyon Wash shows its dimensions where it runs to its confluence with the San Pedro River (the light-colored horizontal strip at the center of the photo), below:

The most recent of the really large floods that have produced this wide floodplain date from 1983, 1991, and 1993. Aerial photographs show where the stream carved out a massive "U"-shaped cut during these floods:

In this aerial photograph (taken in 1996), the Cascabel Road is shown as a series of white dots across the upper part of the frame, running from east to west (right to left). The black arrows show the the flow pattern that produced this large horseshoe of erosion, the latest of which threatened the substantial residence shown as a whitish rectangle in the center of the photo.

We have recently obtained a copy of a photo dated to a flood at the road-wash confluence said to have occurred in 1984, shown below. The view is toward the southeast. (Max Taylor, a long-time ranch owner in Cascabel, stands at near left.)

Note the red Pipeline worker transportation bus caught in the flood at the left with its front end angled downstream, and the apparent depth of the waters along the near bank. (Note also that the flood had previously been much larger, the edge of the flow extending out beyond the location of the semitrailer truck parked at the far side of the road.) The bank stabilization with tires and chain link shown at lower right was part of a project done by local volunteers and the County after the 1983 floods rearranged the wash. (It is almost invisible today.) (Thanks to Barbara Clark for this information.)

This scene occurred long before the roadway here was given a concrete flooring, but the point is that Hot Springs Canyon produces floods of widely-ranging power, and the one of August 07, 2006 was of very modest size historically speaking.

Thanks to Lynn Smith-Lovin's flight reporting in our area, we have this aerial view of the San Pedro River near its triple confluence with Hot Springs Canyon and Paige Wash, taken on August 25, 2006:

The image above looks downstream toward the northwest from a point just below the triple confluence. By that time the river flow had receded well below its recent maximum, the extent of which nonetheless remains evident. Click on the image for a close-up, which shows more clearly how the stronger flood previously struck hard against the left bank of the Wash (far left of the close-up), then rebounded across to the right, overflowing the right bank and spreading out beyond the normal banks on its run downstream (far right of the close-up). You can see that the ground is still damp on both sides of the current flow.

Below: the San Pedro running in flood near the old Taylor Ranch, near the Hot Springs Canyon confluence. This photo was taken just downstream from there, looking upstream in August of 1998.

In more "normal" times -- like the moment this image captures during the intense winter-rain drought of January 2006 -- the River at this point is only one of dead leaves:

Below: Soza Canyon Wash, running down out of Mica Mountain (to the west, in center background); a very wide wash in its lower reaches, this was viewed from lower Soza Mesa looking toward the mid-afternoon sun of December 2001: (click on image below to enlarge)

Below: view of the SP floodplain from Harold & Mignon Elliott's place on the right-bank terrace, looking toward buildings at El Potrero north of Milepost 26. (Beneath the gallery forest in middle background, the stream is again perennial at this location.) (Oct.2002) (click on image below to enlarge)

At Milepost 31, the cottonwood gallery forest stands out in another stretch of perennial stream, shown in April 2005 below, first looking upstream and then (at right), looking across: (click on each image below to enlarge)

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Between Milepost 31 and 32, the road runs past the Redington Narrows, shown at right below when the river was running in flood in August 1998. (the photo at left was taken on the same day near the location shown above.) (click on the right-hand image below to enlarge it.)

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Below, this map shows the Narrows near dead center, with a Gaging Station (now defunct -- the current one is further north at the San Pedro River Bridge in Pima County) marked as located in it. The two arms of the Narrows, pointed toward one another in a northeast-southwest orientation, are clearly visible here.

Below are two more comprehensive views of the Redington Narrows photographed from further upstream in April 2005, when the riverbed was dry at this point (click on each image below to enlarge it.):

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From the vantage point above, the effects of the 1983 and 1993 floods on the river floodplain can be seen. Beyond the first terrace above the floodplain (which is visible in the near foreground of each image), the floodplain was almost entirely scoured of vegetation here, including the whole expanse from left to right upstream from the bottleneck of the Narrows.

As you can clearly see, a band of hard reddish-gray rock straddles the river at this point. This is a Lower Miocene deposit of sedimentary rock called the San Manuel Formation (see Geology of Hot Springs Canyon for more details on this Formation); at this particular location it is distinguished as the "Soza Canyon facies", and contains a high frequency of volcanic clasts in its tilted sediments, as can be seen below: at left, a broad view of the strata; at right, a closer view of its components (click on each image below to enlarge it.):

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Further downstream, near Milepost 32, right at the Cochise County-Pima County line, the old, high terrace above the River has produced a remarkable vegetation: (click on the image below to enlarge it.)

On this high and dry terrace, the dominant vegetation (aside from the grasses) all the way to the terrace's cliff edge is Jumping Cholla. For more details, see Cholla.

At Redington (see map below), two large washes meet the San Pedro -- Buehmann Canyon running from the Catalinas and Redfield Canyon from the Galiluros. These both form deep canyons in their higher reaches. The beginning of the Redington Road (which crosses Redington Pass in the Rincon-Catalina Complex to the west and connects with the Tanque Verde Road in Tucson) is visible in the bottom left-central portion of the image.

The San Pedro floodplain begins to broaden downstream from the Pima County line. North of Redington, below, looking toward the northwest from a terrace near the Davis Ranch:

Below, the San Pedro runs from right to left, with the northern Galiuro Mountains in the background. As usual, substantial, high terraces flank the floodplain at many points along this part of the river. (December 2002) (Click on the image to enlarge it.)

Below: further north of Redington, looking westward at the broad expanse of lower Alder Wash (which drains the north-facing slopes from the top of Mount Lemmon). The wash is running down toward the viewer, from its source in the central Catalinas (note the big stand of very old Saguaros located on the terrace at far right): (click on image below to enlarge)

On the map below, see Alder Wash running down from the Catalina Mountains. Directly across from it lies a much deeper wash, in Kielberg Canyon, which drops to the River from the closer slopes of the Galiuros.

Below left : Kielberg Canyon viewed from Alder Wash, looking East; China Peak of the Galiuros rises in the background (July 2002): below right: Kielberg Wash looking upstream from High Mesa: (click on each image to enlarge it.)

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This wash (above) runs past Pliocene lakebed-deposit cliffs (see "Quiburis Basin Geology") which are visible on both sides of the Canyon, to its confluence with the San Pedro, where the floodplain is very broad and sandy (below, looking eastward toward the outflow of Kielberg Wash):

Further downstream, near Whitlock Wash (and near San Manuel), the waters of the San Pedro surface again:

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