We began our journey southward on Interstate 25. Never having seen the Chihuahuan Desert, I knew little about what to expect in the way of its flora, fauna, geology, and climate. My Audubon Society guide to America’s deserts, which I purchased just prior to our trek, indicated that the Chihuahuan spread into New Mexico from northern Mexico in “four fingerlike projections,” with the northernmost projection reaching to “a point just north of” the town of Socorro, which was on our itinerary.
Of course, there was no sign, official or unofficial, along I-25 announcing our entrance into this desert. However, as we passed the town of Belen, 40 miles north of Socorro, I sensed that the character of the landscape was changing. The Rio Grande, which parallels the interstate to the east, was still bordered by dense woods and the occasional agricultural field greening with spring. But, just west of the interstate, the land was disrobing, beginning with the disappearing junipers. Disappearing, as well, were the bones of the land, those rock outcroppings, so common west and north of Albuquerque; they were now being replaced by mere soils given to erosion. When Sierra Ladrones―Thieves Mountain, an isolated, dual-peaked range―appeared in the west not far from highway, I could see that the peaks and slopes it presented were not cloaked in dark alpine forests like those of the Sandia Mountains beside Albuquerque and the Manzano Mountains just south of the Sandias; rather, they were dotted with smaller trees and armored with barren rock. Meanwhile, in the far southeast, I saw, peeking above the horizon, a jagged range that appeared to be devoid of tall forests as well.
As we progressed south of Socorro, now well into the desert, one thing was certain: this was not the Sonoran Desert I had witnessed during my visit to Tucson, Arizona, the previous decade. There were no multi-armed saguaro cacti waving at me; no luxuriant palo verde trees lending their cool green accents to arroyos; no teddy bear cholla cacti with their thousands of murderous spines aglow and threatening misery to the rookie Sonoran pedestrian. The Sonoran is a subtropical, and thus a far more diverse, desert than the Chihuahuan. And, many would agree, a lovelier one. Erna Fergusson described the Sonoran as having “a beauty no fabled wood ever equaled.” The Sonoran is also known as an “arboreal desert,” one in which, in the simple observation of author and modern-day Southwest explorer Alex Shoumatoff, “[s]o much of the vegetation rises over your head.”
Alas, the high-elevation Chihuahuan Desert we were now witnessing was primarily a monotonous one of squat shrubs and cacti, scattered grasses, and only an occasional tree, which I would later identify as the desert willow.
Yet it was now, for better or worse, our desert, and soon I would learn that it existed in New Mexico for two main reasons. One was the “rain shadow” effect of Mexico’s Sierra Madre Occidental mountains―massive landforms blocking the passage of rain-producing weather systems, condemning the mountains’ leeward expanses to unforgiving aridity. The other was a meteorological phenomenon I would find more challenging to understand: the Hadley cell, equatorial atmospheric activity that prevents the condensation of moisture, thus creating the Chihuahuan Desert in southern New Mexico, west Texas, and northern Mexico.