Chimneys Intro

Drunken Cowboys and Indians: The Chimneys

The trail to the Chimneys is one of the easiest in Big Bend. Granted, it may be a wee hot in the summer (we did it in June), and you have to watch for the horse-crippler cactus (Echinocactus texensis - I got one through the sole of my shoe), but the trail is well-developed and the topography almost level. A stroll of only three miles gets you there.

You see, in the image below, the trailhead with Kit Mountain to the left, shadowed by clouds, and Black Mesa in the distance, mostly in sunlight. The view is almost due west. Black Mesa gets its name from the dark Alamo Creek Basalt, which was erupted between 47 and 34.5 million years ago and forms the top of the mesa. In moist places like Hawaii, basalt quickly weathers to red soil, but it tends to be more resistant in dry areas such as Big Bend. In addition, not all of the Alamo Creek Basalt is actually basalt. It consists of several lava flows, some of which are trachyandesite in composition, which is a volcanic rock with more silica and alkali metals than basalt. The Alamo Creek basalt flows themselves are also alkaline. The Alamo Creek basalt extends from here north to Dogie Mountain (just outside the west side of the park) and west to the town of Lajitas (just outside the southwest side of the park along the Rio Grande). (The most interesting thing about Lajitas is that its mayor is a beer-drinking goat named Clay Henry, party affiliation unclear.)

Figure 1

In the picture below, my brother, Randy, is snapping a telephoto just as a swath of sunlight illuminates the chimneys. His photo is displayed in the next picture. (The first photo was also taken with magnification, but not as much as Randy's.) The clouds were certainly welcome due to the heat, even though they did make photography difficult. The Chimneys are about 2.5 miles away at this point, and Black Mesa is several miles beyond that. Note how green the vegetation is. This was in 2007 after an unusually wet spring in West Texas.

Figure 2

Figure 3

The next three images are of the Chimneys. The gap in Mesa de Anguila (Sierra Ponce in Mexico) marks the eastern margin of Santa Elena Canyon. The Big Bend website says the Chimneys are a volcanic dike, whereas the book Big Bend Vistas by William MacLeod claims they are a row of volcanic necks This latter interpretation seems unlikely to me. On the the other hand neither interpretation explains the stratification that seems to be present in these outcrops. However, if this apparent stratification is due to weathering as ground level was lowered by erosion, then I would favor the volcanic dike interpretation.

Figure 4

Figure 5

Figure 6

The premier attraction of the Chimneys is the display of Native American petroglyphs. The image below shows the pillar of rock on which petroglyphs were inscribed.

Figure 6

The picture below is a close-up of the petroglyphs. I'm sure archeologists would find meaning in these, but how do they know they weren't made by Native Americans bored out of their skulls? After all, what can you do in the desert for fun? Well, if you have a gun, target practice using the petroglyphs might be one possibility. Note the circular petroglyph toward the upper right, riddled with bullet marks. One can imagine drunken cowboys, also bored out of their skulls, taking potshots at it. Now, whether or not this is desecration, depends on when it was done. If it was done long enough in the past, it would now be history. On the other hand, inscribing your initials in the fireplace of the historic Homer Wilson Ranch, as we witnessed on a backpacking trip along the Dodson Trail, is definitely desecration.

Figure 7

To the south of the Chimneys is Bee Mountain with layers of Chisos Group volcanics showing as outcrops. Also note Santa Elena Canyon to the right. (The Chisos Group of rocks consists of 47 to 32 million year old sediments, tuffs, and lava flows.)

Figure 8

The following view is looking west from the Chimneys. In the distance are the high Chisos Mountains, Carosel Mountain, and Elephant Tusk (an igneous intrusion). Between Carosel Mountain and the high Chisos lie the Sierra Quemada (Burned Mountains). Carosel Mountain overlooks the ranch house of pioneer rancher, Homer Wilson.

Figure 9

Your constant companion on the Chimneys trail is the east-west elongated Kit Mountain on your south, and it is time to take a look at this feature. In the image below you can see the bulk of the mountain consists of Chisos volcanics (note the white volanic tuff) with a cap of Burro Mesa Rhyolite. Rhyolite is a volcanic rock high in silica, and tuff is hardened volcanic ash produced by an explosive volcanic eruption.

Figure 10

On the west end of the mountain is a bit of an unusual feature, or at least so it seems to me. Behind the ridge in the foreground is a depression that apparently forms a dry lake bed. This depression may be due to the fault that has been mapped to run along the northern border of the mountain.

Figure 11

As you approach the trail head on your way back, you get a great view of the layer-cake stratigraphy of Goat Mountain (below). You can clearly see the volcanic strata that have been unveiled by differential erosion. The dark strata at the bottom of the mountain belong to the Bee Mountain Basalt. Above that are Chisos volcanics, including the Mule Ear Spring Tuff (light color) and Tule Mountain Trachyandesite. At the top are the two members of the Burro Mesa Formation: the Wasp Spring Tuff and the Burro Mesa Rhyolite. Both were erupted about 29 million years ago. The units below them were emplaced between 34 and 32 million years ago. (Note: Recent research has cast doubt on the identification of the Tule Mountain Trachyandesite. This trachyandesite may have been erupted three million years later than that identified as the Tule Mountain unit.)

Figure 12

The oldest rock along the trail is the Ash Spring Basalt at 34.5 million years. The next image is an outcrop of this rock to the north of the trail as you approach the trail head and the end of your six-mile stroll.

Figure 13

FORWARD to the Window

BACKWARD to the Lost Mine Trail

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