We're about to hike along the south rim of what geologists call the San Ysidro anticline, or alternatively the Tierra Amarilla anticline. Trail bikers call it the White Ridge . Millions of years ago, things looked quite different here: we're peering into a valley that was a ridge, not a low point. The peak of the ridge followed the center of the valley you see here - so the highest part of that ridge is now the lowest part of today's valley. Geologists call this "inverted topography": the highest parts of the land have been transformed into the lowest parts. How did that happen? The rock layer that covered the top of the ridge was made of shale, limestone, and gypsum. You can see the white gypsum on the trail at the edges of this photo (geologists call it the Tonque Arroyo Member). This hard rock cover was eroded off the top of the ridge by wind, precipitation, and freezing and thawing. As it wore away, much softer sandstones, mudstones, and siltstones beneath ...
Casamero Pueblo is a Chacoan outlier Great House site located between Grants and Gallup, NM. This two-story Great House was occupied between A.D. 1000 and 1125. It had 22 ground floor rooms and may have had six second-story rooms. It is located 45 miles south of Chaco Canyon, making it a Chacoan outlier community. You can see its walls in the far distance, to the right of the sign, at the base of the bright red sandstone cliffs of Tecolote (Owl) Mesa. The two alcoves just to the right of the sign form the large "owl's eyes" that give the mesa its name. The Great House had T-shaped doorways that are characteristic of Chacoan architecture, one small interior kiva, a great kiva, and two Chacoan roads. Casamero was settled during a time that corresponded with a surge of building in Chaco Canyon – around A.D. 1050. It existed during much of the florescence of Ancestral Pueblo culture in Chaco Canyon, was clearly related to it, and declined in unison with it. When something in...
We watched the Gila River flow at The Nature Conservancy's (TNC) Lichty Ecological Research Center, four miles south of where it emerges from the Mogollon Range (in the background), and the rugged Gila Wilderness. The TNC's Gila Riparian Preserve here protects more than 1,200 acres of fragile Southwest riparian habitat and verdant gallery woodland along the Gila River, the last of the Southwest's major free-flowing rivers. The Gila is a rare example of a river with a natural pattern of flows that are unimpeded by dams. They range from winter floods to snowmelt run-off and low flows in spring. A variety of native plants and animals have adapted to these seasonal pulses of flooding and drought, including a number of endangered species. Two-and-a-half miles upstream from the Lichty Center, we set out to hike to the mouth of the box canyon where the Gila River exits the mountainous Gila Wilderness: the world's first designated wilderness area and New Mexico's largest....