Guadalupe Mountains National Park: Permian Reef Trail

Mollusk Fossils

After lunch on Tuesday, November 13, Phil climbed into the tent with Sylvan for the little guy’s nap. Meanwhile Sean, Adam, and I decided to get in a second short hike for the day, this time one a bit more ambitious than our walk through the foothills with the baby that morning.

We chose to check out at least part of the Permian Reef Geology Trail near the entrance to McKittrick Canyon. The entire trail is a 4.2-mile out-and-back 2,000 feet up onto Wilderness Ridge near the Texas-New Mexico state line. We wouldn’t be able to do the entire trail, but we figured it would be worth it to see some of it. We were particularly keen to see fossils.

Wilderness Ridge

We arrived at the McKittrick Canyon trailhead at about a quarter to two. The National Park Service would be locking the gate at 4:30pm, which gave us a couple hours to see how far up the trail we could get.

We didn’t linger too long at the trailhead. After using the restroom, we set out.

Capitan Reef capping Wilderness Ridge

The trail ended up on Wilderness Ridge, a spectacular portion of the exposed fossil reef that caps the Guadalupes. Here at the mouth of McKittrick Canyon, the topography we see actually mirrors the underwater topography from when the reef was alive (some 260-270 million years ago at the end of the Permian Period (that’s before the dinosaurs)).

The gargantuan reef formed at the edge of an underwater shelf extending from dry land into the Delaware Basin. Where we stood at the trailhead, we were at the equivalent of being on the deep seafloor beyond the shelf. The slope of Wilderness Ridge from the foothills approximates the slope of the shelf from the reef in shallower waters. Beyond the reef, a shallow lagoon ultimately led to the shore and dry land. Permian Reef Geology Trail in effect climbs up the slope of the deep sea floor to the shallow reef and lagoon. Only in a desert in West Texas.

The effect is magical because you can spatially imagine being on the sea floor and making your way up the slope of the underwater shelf toward the immense coral reef.

McKittrick Creek

We crossed the dry bed of McKittrick Creek at the mouth of the canyon before turning onto the Permian Reef Trail proper.

Soon we were climbing gently through scrubby brush. We encountered the first interpretive marker, but unfortunately, all it had was the number without any signage. We didn’t have the guide because the bin was empty at the trailhead. Happily, Sean had cell service, so he pulled up a pdf of the guide.

Here’s marker 3 in the image above. And this is the guide’s entry, by way of example:

Every rock provides clues to the forces that have shaped the land. Geologists have studied thin cross-sections of this rock with microscopes and have found that some of the pebbles embedded in it are made of a type of limestone called boundstone which was formed by algae, growing around sponges. These types of organisms only grew on the reef, so it has been moved from its place of origin. The reef was made by billions of organisms and grew vertically until environmental conditions could no longer support continued upward growth. The reef community then started growing outwardly towards the ocean basin and became unstable. The force of wave-action and gravity tore off pieces of the reef. These pieces formed a steep slope of debris below and in front of the reef. Some particularly violent collapses carried debris all the way out into the deep sea floor where the pieces were buried and fossilized.


Frijole Ridge

Across the mouth of the canyon, Frijole Ridge stretched in an undulation of slopes all the way back to Pine Springs.

After marker 3, the trail leveled out and a little side loop trail cut away and down a low ridge. We stayed on the main trail and turned west into and above McKittrick Canyon.


Ocotillo and Prickly Pear

Ocotillo and Lechuguilla


Prickly Pear and Alligator Juniper

Ocotillo. Image: Sean M. Santos

As the trail left the ridge and started to traverse the canyon wall, it became unexpectedly dramatic where mudstone and wakestone that had been laid down along the seaward slope eroded away from the slope of the canyon’s mouth.


Frijole Ridge

Image: Sean M. Santos

The trail led behind the monoliths to a lush little microclimate.

Prickly Pear

Whole trees grew back here, protected from the baking heat of the sun on this southward facing slope.

Prickly Pear

Texas Madrone

After we emerged from the outcrops, the slope the trail traversed became steeper, and we were treated to wonderful views into McKittrick Canyon. We had actually gained a fair amount of elevation already.

Brachiopod Fossils

At this point some seven hundred feet up the slope, we would still have been in deep water 250 million years ago, but debris from the reef that slid down the shelf carried with it brachiopods, which resemble modern clams, although they are unrelated.

Brachiopod Fossils

After studying the brachiopods, we continued on through another couple switchbacks.

Rounding a bend in the slope, we got a wonderful view of the reef.

But now it was 3pm, and although the trail beckoned us to climb higher, it was time to turn around and head back down. We did not want to linger and risk getting stuck for the night behind a locked gate.

All three of us agreed that the Permian Reef Geology Trail is an absolute gem of a trail. It certainly spoke to our shared interest in fossils, science, and learning. We are determined to return and take our leisurely time with the trail, doing it as a backpack and staying overnight up on Wilderness Ridge.

Alligator Juniper

Mollusk Fossils

On the way back down, we stopped near the brachiopods to more closely examine marvelously preserved fossils of mollusks.

Mollusk Fossils

Mollusk Fossils

Brachiopod Fossils

We continued to retrace our steps.

Ocotillo and Prickly Pear

After the outcrops, we were making good time back down the trail, so we circled around onto the geology loop side trail.

Unfortunately, its markers weren’t listed in the guide. Sean thought that perhaps he was missing part of the file, but later on a ranger explained to Adam that some of the markers indicated very advanced or esoteric geological concepts, so the trail guide skipped them. Both Adam and I bought the complete book about the trail by the Texas Bureau of Economic Geology.


Mule Deer

Near the bottom of the trail, we were startled by some Mule Deer browsing on the slope.

Mule Deer

Chert, which formed on the deep sea floor

Adam and Sean studying conglomerates and chert

Sticks indicate that the trail does not follow the access road.

We arrived back at the trailhead right at 4pm. We’d done a none-too-shabby 2.5 miles on the trail with a vertical rise of about 800 feet, about a third of the entire trail. All three of us marveled at what a great short hike it had been. We had to return someday.

The hike had given Adam a tiny taste of McKittrick Canyon. We resolved to return on Thursday with Phil and Sylvan after we broke camp, but before we continued on to Carlsbad.

It had been a warm afternoon, considering, for a hike, but as we noticed ice from water seeping from a vessel near the trailhead, we could’t forget that the sun was fast disappearing and that we were in for another cold night.

Adam’s cell service returned. He had a message from Phil that he and Sylvan were awake. So we headed back to the campground.

Phil and Adam discussed it, and they decided that they would forego sleeping in the tent that night and instead take Sylvan to a hotel. Although not forecast to be quite as cold as the previous night’s eighteen degrees, the coming night was still forecast to be in the twenties.

It was the right decision, undoubtedly. Happily for Sean and me they gave us all the pillow and blankets from their tent, so ours now looked like the boudoir of some sort of elegant nomads.

The guys would stay in camp for dinner, and we began putting together an instant risotto with chicken.

As the evening’s darkness deepened, we could see the flares from oil wells out on the horizon. The area was in the midst of an oil boom. The organic material on the deep sea floor yielded rich petroleum deposits in this part of Texas and New Mexico.

While we were eating, we spotted some lights up on the slope of Guadalupe Peak. At first they were blinking, and we wondered if someone was signaling distress, but then after looking with binoculars, we figured out that the lights were two hikers with headlamps descending the trail in the fast-thickening darkness.

After dinner, we had a dessert of my birthday cheesecake from the evening before.

The guys packed up Sylvan into his carseat, said goodnight, and drove off. They’d be back for breakfast in the morning.

Sean and I turned in and lay reading in the tent for a while before falling asleep.

2 thoughts on “Guadalupe Mountains National Park: Permian Reef Trail

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