The Raton Basin

Driving along I-25 between Walsenburg, Colorado, and Raton, New Mexico, one enjoys spectacular scenery, including lofty peaks, high mesas and rugged canyons. One would certainly not imagine that this area was once a basin!

Yet, back in the Cretaceous, some 100 million years ago, when Tyrannosaurus rex and his cohorts roamed the planet and a broad seaway stretched from Texas to western Canada, a geologic basin extended across this region, tilted upward to the west; marine shale, known as Pierre Shale, covered the floor of the basin, deposited by the Cretaceous Sea. As the Rockies began to rise and the sea retreated to the south and east, coastal sands settled on the shale and have since hardened into the sandstone of the Trinidad Formation. Then, toward the end of the Cretaceous, a delta ecosystem spread across the region, destined to yield the shales, siltstones, sandstones and coal seams of the Vermejo Formation; coal has been mined from this formation since the 1800s and methane has been retrieved since the 1980s. As the Cretaceous gave way to the Tertiary Period, alluvial debris from the rising mountains covered the area, the source of conglomerates that now comprise the Raton Formation; harboring pockets of coal, this Formation is famous for its exposure of the K-T boundary, within which a high level of iridium supports the theory that a catastrophic meteor impact ended the Cretaceous and wiped out the dinosaurs. Finally, during the Paleocene, alluvial sands and muds of what is now the Poison Canyon Formation covered any remaining evidence of the underlying geologic basin.

Since then, in concert with continued uplift along the Rocky Mountain corridor, granite intrusions pushed up into the sediments, later to be uncovered by erosion to reveal the spectacular Spanish Peaks of southern Colorado, complete with Eocene-Oligocene lava dikes that formed as these massive plutons rose. In the late Miocene, about 9 million years ago, the Raton-Clayton Volcanic Field developed across northeast New Mexico, spreading thick pools of basalt across what is now the Colorado-New Mexico line. This hard cap of basalt protected the underlying Tertiary and Cretaceous sediments, yielding a chain of high mesas that stretch from the base of the Rockies to the Oklahoma Panhandle, separating the watersheds of the Arkansas and Cimarron Rivers.

Musk Hogs

Collared peccaries, otherwise known as javelinas or by their more colorful title of musk hogs, are native pig-like residents of the Sonoran and Chihuahuan Deserts of the Southwest U.S., from southern Arizona to southwest Texas. They and other peccary species are also found southward through Mexico, Central American and most of South America. All are descendents of a Eurasian ancestor that split from the common pig lineage back in the Eocene, some 50 million years ago.

Living in herds of up to 50 individuals (10-20 is typical), collared peccaries roam the canyons and arroyos of the Desert Southwest, under the control of a dominant male. He breeds with females in the group throughout the year and pregnant females temporarily leave the herd to deliver their young (usually 2) in a den or hollow log. Older sisters help to raise their new siblings and newborn females are sexually mature within a year.

Thinner and longer-legged than common pigs, collared peccaries have a coarse coat of gray-brown hair with a darker mane down their back and a lighter ring around their neck; while their eyesight is rather poor, these desert residents have a keen sense of smell. Short, sharp tusks offer some protection from predators (mountain lions, coyotes, bobcats) but their aggressive nature and group mentality provide their best defence. Omnivorous, peccaries feed on a variety of plant materials (prickly pear cactus and agaves are favored) but also consume eggs, reptiles and carrion; avoiding the heat of mid-day, they usually forage in the early morning and evening hours. The name "musk hog" is derived from the potent musk gland on their upper rump which they use to mark their territory and one another.

The Desert Raccoon

Natives of Central and South America, coatimundis have spread into the Sonoran and Chihuahuan Deserts of the southwestern U.S. Formally known as white-nosed coatimundis, these members of the raccoon family, unlike their more widespread and familiar relatives, are diurnal and gregarious, often moving about in noisy bands composed of females and their young.

Adult males, twice as large as the females, weigh up to 25 pounds and tend to be more solitary. Mating occurs in the early spring and 4-6 young are born after a gestation of almost 3 months. Females often use rock crevices for nursery dens but she and her offspring later use crude arboreal platforms for sleeping and resting. Wandering about for much of the day, these omnivores locate food and prey with their long, tapered snout; insects, lizards, eggs, nuts and fruit comprise most of their diet. Coatimundis are agile climbers, equipped with sharp claws to grasp limbs and a long tail for balance.

Favoring wooded canyons of the Desert Southwest, white-nosed coatis and their brown-nosed South American cousins are threatened primarily by habitat loss. Natural predators include mountain lions, coyotes, bobcats and golden eagles in the U.S. and jaguars, ocelots and boas in Central and South America. Known to live up to 15 years in captivity, coatis have a natural life span of 6-8 years.

The Permian Reef

During the Permian Period, about 260 million years ago, a shallow, tropical sea covered what is now southern New Mexico, West Texas and northern Mexico. A broad arm of this sea, known to geologists as the Delaware Basin, was rimmed by a massive reef, formed by the calcareous shells and body parts of marine organisms.

As Pangea broke apart, tectonic uplift cut off this sea's connection with the ocean and, over thousands of years, it evaporated, leaving the reef encased in halite, gypsum and other deposits. Additional layers of sediment and wind-blown deposits covered the region througout the Mesozoic Era and Tertiary Period, obscuring all evidence of the Permian reef. Then, during the Miocene-Pliocene Uplift, some 20-10 million years ago, the reef and its encasing sediments were raised and erosion gradually uncovered portions of the reef's Capitan limestone, with its cargo of marine fossils.

Today, much of the 400-mile long, U-shaped reef remains buried below the landscape of West Texas and southeastern New Mexico but its massive limestone formations are exposed as the Apache, Guadelupe and Glass Mountains. In addition, one section of the buried reef, in New Mexico, has been hollowed out by acidic groundwater, yielding Carlsbad Caverns, among the largest and most spectacular cave systems on our planet.

Wintering Cranes

Sandhill cranes breed across the Arctic tundra of North America and in scattered regions from the Upper Midwest to the Intermountain West; a separate population inhabits the dry prairie region of south-central Florida. Come fall, most of the northern flocks migrate to wetlands from the Texas Gulf Coast to Southern California and southward into Mexico.

A large percentage of these wintering cranes congregate at a chain of National Wildlife Refuges across West Texas and southern New Mexico; these include Muleshoe NWR, northwest of Lubbock, Bitter Lake NWR, northeast of Roswell and Bosque del Apache NWR, south of Socorro, New Mexico. Feeding in crop fields and boggy grasslands throughout the day, the cranes return to these refuges at sunset, roosting in broad, shallow lakes that offer protection from nocturnal hunters.

It is the opportunity to observe these large flocks of sandhills as they arrive at sunset or depart at sunrise that draws birders and naturalists to the Southern High Plains in the middle of winter. Of course, other wildlife can also be seen at these refuges, including snow geese, bald and golden eagles, prairie falcons, a large variety of waterfowl, roadrunners, longspurs and wintering bluebirds; mammals include coyotes, mule deer, pronghorns and, at Bosque del Apache, porcupines.