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Prologue: Welcome to the world's most famous entrenched meanders––goosenecks by the more common term. If you have ever rafted the typical slow and muddy water of the San Juan slipping through this vicinity, you cannot help but be blown away by these meanders rising high above you. Their bulwarks actually force the river to take a detour around the obstacles in their path. Then again, that's what meanders: they alter the course of a river and make impressive backdrop scenery. But there is more to the scene than this and all that will be explained in today's diary.

Location/Geography: Near the southern border of Utah, the closest town is Mexican Hat. Area: 10 acres (40 sq. km). Elevation: 4,949 feet.

Spotlight: World's greatest entrenched meanders, bar none. The muddy, slow San Juan River taking the so-called long way around (by way of the meanders it carved). Hiking. Focus: geology, hiking and classic desert country scenery.

Snapshot: Goosenecks SP overlooks a series deep and impressive bends of the San Juan River. These serpentine bends are considered the most classic entrenched meanders in the world. Here, downcutting by the river has uniquely dissected the crest of the Monument Uplift, which defines a broad dome that buckled during the Laramide Orogeny event some 66 million years ago (also the great uplifting of the Rocky Mountains, and soon thereafter the birthing of the Colorado Plateau). As a state park, however, Goosenecks is largely undeveloped. Primitive is another way to describe it. Nearby Mexican Hat is the major scenic hub and tourist hamlet, especially for boaters coming off the river. From the summit overlooking the meanders, clear views of Monument Valley are seen in the southeast. Closer, the Moki Dugout (sometimes spelled “Moqui”) leading to the summit of Cedar Mesa and the Raplee Anticline (a.k.a. the Navajo tapestry of colorful rocks) adds to the long, wide view. Muley Point and Valley of the Gods (see Destinations list) are all within 15 to 20 miles (24 to 32 km) of the goosenecks.

The awesome view from high, high above the meander formation folds
(Diary continues after the fold)

Rowing down the usually slow and muddy San Juan River!

Guided Tour Essentials: A major blueprint of change created this geography of diverse features. River gravels on higher ramparts, such as nearby Douglas Mesa, are geologic clues to just how much of a geophysical change occurred before and after a regional upwarp of the landmass. (An "upwarp" defines a broad anticline with gently sloping limbs formed as a result of differential uplift.) This crustal force defines the Monument Upwarp that fabricated the prominent vistas common in this sector. In the geologic scheme of things, it was some twenty million years ago when the San Juan River carved the initial outline of oxbows into the buried rock layers. These formations were later exposed, revealing the impressive site we see and admire today. Where the goosenecks formed, rocks at their upper surface level represent the Honaker Trail Formation, while older Pennsylvanian Hermosa Formation is exposed in the gorge where the silt laden river lazily flows some 1,000 feet below the summit. This is Mesozoic Era Comb Ridge country. Its colorful Triassic Period rocks form long lines of cuestas (denoting a ridge formed by gently tilted rock strata in a homoclinal structure) and hogbacks (denoting ridges formed from a monocline, such as Comb Ridge's remarkable landform and composed of steeply tilted strata of rock protruding from the landscape).

The unique and scalloped profile of the amazing and elongate Comb Ridge (with a rather daunting subject for a foreground image for the sake of perspective and thrills).

Combined, the sculpting process is due to large-scale differential erosion and weathering of the sedimentary materials. At the crest of the ridge is the cross-bedded Navajo Sandstone––he petrified sand accumulation from the Jurassic Period and much like the environs of a Sahara Desert. Here at the overlook the crested top of the goosenecks reveals its unique differential-erosion sloping facade of marine limestone.

Geology: The Goosenecks formations were some 300 million years in the making. The Honaker Formation comprise the upper sediments, the Pennsylvanian Hermosa Formation lies somewhat in the middle and the Paradox Formation forms the base. These distinct sedimentary deposits define the principle geology of this cleaved, wrinkled and folded topography.

Millions of years ago, the Monument Upwarp (a wide, immense north-south anticline) forced the river to carve a series of incised meanders that deepened over time. This event simultaneously happened as the surrounding landscape slowly rose in elevation. Hence, without uplift of the terrain, downcutting by rivers would not have occurred. Eroded by water, wind, frost and gravity, the famed Goosenecks of the San Juan constitute a classic location for observing incised meanders.

The pronounced turns in the indolent river's course through this region meanders back and forth, flowing for more than 5 miles, while progressing forward for an amazing single linear mile. The resulting process (by erosion) works in tandem with the slope of the river. If the slope of a previously established meandering stream is suddenly increased, which took place in this locale, then it will resume its downward erosion. Thus, the base level of the stream is reduced.

From the satellite's extreme view. . .voila!

As the stream erodes downwards, its established meandering pattern will remain as a deep valley. This process is known as an incised meander, and sometimes called an entrenched meander.

An overview of the entrenched meander series

The San Juan River: This usually slow-moving body of water established its route westward and through this region sometime during the late Oligocene (some 23 million years ago) or early Miocene (some 15 million years ago). At the time, the river was forced to abandon its previous route toward the northwest, where it had cut across portions of southwestern (present-day) Colorado. Attempting to find the lowest spot between the Monument Upwarp to the north and the Defiance Plateau to the south (near Canyon de Chelly), the initial route in this vicinity was somewhat south of its current path. (Proof of this are the older river gravel deposits on the south side of Douglas Mesa are remnants from this former established route.) Once the river got past the western sector of the upwarp, this earlier version of the San Juan turned north, then headed toward a larger drainage (today's Colorado River).

Today’s San Juan is a major tributary of the Colorado River, measuring 400 miles long, with an average flow of 3,770 c.f.s. (cubic feet per second). The c.f.s. remarkably drops after the spring runoff and increases temporarily only during summer monsoonal rains. It's not what one would dub a whitewater river by any stretch of the imagination, though there are some decent rapids here and there (none higher than Class III) for part of the summer. What the San Juan lacks in whitewater (and more like brown water since it’s typically muddy) it more than makes up for with spectacular scenery. There are also scores of Ancestors ruins along its meandering course. Rising in southern Colorado along the southern slope of the San Juan Mountains, it flow down and to the west of the Continental Divide (in southwestern Colorado). From there it continues into New Mexico, briefly flowing across the southwestern corner of Colorado and Utah, eventually merging with Lake Powell. The San Juan River's most famous stretch is arguably the goosenecks.

Upstream from the goosenecks, the peaceful, and some say, idyllic, San Juan moseys on.

And to think how this indolent body of water did all of this. . .

A more dramatic B/W depiction beneath a dramatic sky!

Bonus Details: For those with the stamina, there's only one way down to the San Juan River from the Goosenecks overlook: the Honaker Trail. For a full description of this fairly strenuous trail, see tomorrow's diary. The description also includes a geologic explanation from top to bottom.

Parting shot:

The unique, colorful, bent, corrugated, incised, and heavily warped topography of the regional surroundings where the San Juan River does its lazy meandering thing!

Directions: Travel about 9 mile north of Mexican Hat on Hwy. 163 to Utah 261 (about 5 miles), then U-316 (smaller unpaved stretch) to the overlook.

A regional map, just in case you want to see more sites in this wide and far general vicinity of the Four Corners region:

Contact Information: Goosenecks of the San Juan State Park, P. O. Box 788, Blanding UT. 84511-0788 Phone: 435-678.2238. Fax and Email: non-listed.

And so, DKos community, we come to the end of another trail, another armchair tour. Join me tomorrow for special add-on tour to the Goosenecks, this time a hike to the San Juan River and a closer view of these stunning meanders. It's also going to be quite a 'hoof' for those who have the physical stamina. Then again, there's always the use of one's imagination by way of description about this hike.

As always, your thoughtful commentaries are welcomed.

Rich

http://www.nmstarg.com/....
http://www.grandcanyon.org/....

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Originally posted to richholtzin on Mon Apr 22, 2013 at 09:26 AM PDT.

Also republished by DK GreenRoots and National Parks and Wildlife Refuges.

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