B is for Badlands (Shallow Thoughts)

B is for Badlands

The idea of blogging the alphabet came from a conversation during a hike in Nambe Badlands. It's beautiful a hike that we don't do very often, about 40 minutes from Los Alamos.

"Badlands" is a term for any sort of soft, dry, eroded terrain: a place of mostly dirt and loosely consolodated sandstone, where the terrain erodes into a maze of rounded hills, steep gullies and arroyos, with occasional pillars where harder rocks emerge.

Badlands are often fairly colorful due to the mixture of different rock and soil types. Arizona's Painted Desert, with its stripes of red, white and green, is a famous example. The colors around Nambe and the rest of the Española valley is more subtle: mostly reds, tans, yellows with a few bright white veins running through.

One thing you get in the badlands is views. In the image at left, we're looking southwest past the "barrancas" of Pojoaque. You can see the Pajarito plateau -- the line of white buildings is part of LANL, fairly near my house in White Rock -- and beyond it, the Jemez mountains, Out of the photo behind us are the Sangre de Cristos, running up toward Taos and eventually Colorado.

The badlands themselves are interesting too. They're mostly Santa Fe Group sediments, eroded primarily from the Sangres with a little contribution from the Jemez. In this area, there's a prominent white layer running through. Since it's harder than the dirt on either side of it, it tends to make a "white rim" reminiscent of the famous Canyonlands White Rim, but of course the rock itself is very different. This white rim, while harder than the normal badlands dirt, is still relatively soft, flaky; it erodes to a powder anywhere where it's exposed.

Geology books don't cover this area, but as best I can determine, from papers online, the white layer is probably an ash layer that's part of the Skull Ridge group of the Tesuque formation (those are all finer gradations of the Santa Fe Group). There are four white ash layers, probably erupted from 13-16 million years ago (estimates vary quite a bit, but middle Miocene), possibly from Nevada. So although the white ash is volcanic, it's apparently quite a bit older than most of the Jemez and comes from somewhere else entirely.

It's hard to be sure: I wish geological papers included better maps. In the one Field Geology class I had the opportunity to take, we spent most of our time making maps, and I suspect maps are a big part of what most professional geologists do; but somehow, the geology papers online seem remarkably lacking in maps. Oh, well.

We climbed up to a high lookout for lunch, during which Charlie, our best birder, was scanning with binoculars and discovered an owl sitting in the tower across from our lunch spot. Alas, due to coronavirus "social distancing" concerns, she couldn't pass her binoculars around, but I was able to see the owl, just barely, with the little monocular I keep in my pack. After some debate over its size, and scrutinizing the photos (not good enough to be worth sharing) afterward, Charlie concluded (and I agree) it was a great horned owl.

Badlands exploring is fun; aside from spectacular views, there are always interesting hoodooes and other rock formations to inspect. We did a relatively easy 5.5-mile loop, but there are plenty of other trails in the badlands that I'd like to explore some day.

A few relevant papers I found:

• Alluvial-slope deposition of the Skull Ridge Member of the TesuqueFormation, Española Basin, New Mexico (Kuhle, Smith)
• Stratigraphy of the Santa Fe Group, New Mexico (Galusha, Blick)
• A PALEONTOLOGICAL SURVEY OF A PART OF THE TESUQUE FORMATION NEAR CHIMAYÓ, NEW MEXICO, AND A SUMMARY OF THE BIOSTRATIGRAPHY OF THE POJOAQUE MEMBER (MIDDLE MIOCENE, LATE BARSTOVIAN) (Aby, Morgan, Koning)
• Geomorphology of Espanola Basin (Kelley)