Wednesday, June 1, 2011

Road Trip Reserve: A Geology Field Trip

Nearly Wordless Wednesday

Life is getting serious again. There are wars and rumors of wars, the economy is unstable, and some of my readers want a break from "all that." And it just so happens that last week, I took a day trip to the Catron County Seat, the town of Reserve, in order file a deed at the couthouse, on to Luna on the Arizona Border, and back through Reserve to Quemado. I drove from Quemado, and it is a spectacular drive across mountains, mesas, canyons, and two different watersheds. So, it's time for another geology road trip! Because, despite our troubles, the mountains have been standing for more than 40 million years, they are still standing, and will remain long after we--and our troubles--are gone!

Castle Rock as seen in the early morning, along New Mexico State Road 32. Like many of the mesas in the Mogollon-Datil Volcanic fields, it is a remnant of a Tertiary Conglomerate (the O.K. Bar Conglomerate) preserved by a cap of Quaternary Basalts, that has slowed its weathering. The basalts are very young, extruded less than 2 million years ago. Castle Rock is in the Apache National Forest, in the Largo Creek Wash--in the Little Colorado Watershed.

Further south on S.R. 32, the road plunges over the edge of Jewett Mesa, and into the Apache Creek Canyon. A divide had been crossed, and Apache Creek is part of the San Francisco Watershed. The water that falls on the southern reaches of Jewett Mesa flows into the San Francisco River, then into the Gila, and finally to the Colorado and the Gulf of California. The lava rocks in the center, right of the trees is made up of Tertiary Andesites that are much older than the basalts on Castle Rock. They were extruded more than 37 m.y.a.

South, after plunging into Apache Canyon, the road rides upon Tertiary-Quaternary alluvium of the Gila Conglomerates, and winds along Apache Creek into the small town of Apache Creek, at the junction of Route 32 with New Mexico 12. Apache Creek also sits at the confluence of Apache Creek with the Tularosa River, flowing southwest from its source in a small canyon on Tularosa Mountain. The camera here was pointed north across wetlands at the confluence, looking toward Jon South Mountain.

From Apache Creek, S.R. 12 winds southwest along the Tularosa to Cruzville, and then leaving the river, crosses the faults of the San Francisco Mountains, riding now on Tertiary Ash Flow Tuffs, and again on Quaternary Basalts. Here, looking west of the road across the Gila Formation, we see Mess Box Canyon, composed of a gate of Quaternary Basalts, and framed by older Tertiary Rhyolites and Andesitic domes that make up Higgins Peak and Monument Mountain.

The town of Reserve sits on a mesa at the north end of the Saliz Mountains, and in the Valley of the San Francisco River, that winds through the canyons from Arizona into Luna, and on into the Catron County Seat. Just south of Reserve, between Upper and Lower Frisco Plazas, the Tularosa River and Negrito Creek run into the San Francisco, doubling the size of the river.

After leaving Reserve, Route 12 takes a right angle west through the Five Bar Ranch, and joins US 180, which I took northwest to Luna, where I got my rifle a sling at Southwest Shooting authority. To get to Luna Valley, 180 winds across the San Francisco Mountains. Here we see the cross bedding in dune deposit sandstones that lie below the rhyolites and basalts of Prairie Point Peak. The cross-bedding in this sandstone of the Gila Group is spectacular indeed.

Following the visit to Luna, I turned back along US 180, and S.R. 12, through Reserve and back up Apache Creek Canyon, across the divide, and through Jewett Gap toward Quemado.

Noontime in the Largo Creek Wash, the dark green gymnosperms forming the side of Largo Mesa. Here, in the Little Colorado Watershed, the cottonwoods were just beginning to leaf out in a delicate green, only a few weeks past the last frost in this high Mesa and Canyon country. The waters of Largo Creek flow into the Carizzo Wash that flows just south of the Zuni Plateau, and into the Little Colorado River south of Winslow Arizona. The Little Colorado flows into the Colorado at the Grand Canyon, far north of where the Gila waters join it, near Yuma in southern Arizona, on the California border, and just north of Mexico.

Coming into Quemado from the south along S.R. 32, we cross into the more open canyon and mesa country of the Mogollon slope. Here the mesas are high, and one can see for miles. The mesas and peaks here are all part of the Datil-Mogollon volcanic field, composed of Tertiary and Quaternary volcanics, with a Chain of Craters that march north and east, from the Red Hill near the Arizona border to Mount Taylor. The youngest of the lavas are less than 2,000 years old north in the Malpais. The earth is still very active in this part of New Mexico.

Ragamuffin Ranch lies in this open mesa and canyon country, the canyons created by ephemeral washes that lie above shallow aquifers, creating little areas where the grass is good, and the volcanic sediments create a fertile soil watered by wells pumped by windmills.


Anonymous said...

Very much enjoyed the trip, thank you for letting us ride shotgun.

Elisheva Hannah Levin said...

Thanks, Anon. I enjoyed the trip, too. But I think riding virtual shotgun is the best way, because I tend to stop a lot, getting out with the hammer and the camera, and I slow WAY down in the more dramatic road cuts!