Chapter III: Preface: To Third Edition (2)

Above them, the classifications are less clearly defined and ecologists are less inclined to agree on zonation. The Canadian Zone, if we settle on that name, occurs only in small areas on the map, and most of them north of Santa Fe. These are high ridges and island peaks that tower high enough to tempt the Engelmann spruces. Yet some of these islands occur as far south as the Mogollon Mountains and thus bring Canadian Zone scenes almost to the Mexican border. For hardy ecologists who want to explore high ridges and horns of bare stone which rise as clean as a hound’s tooth clear up into the Arctic-alpine Zone, it is necessary to enter Colorado.

Engelmann spruce forests may be associated with the 10,000-foot level. The blue spruce is very similar, perhaps only a subspecies, but it comes in a little lower. The Engelmann makes a dense forest hardly allowing invaders, but the blue is more tolerant, less austere. It loves the water and is the natural companion of chill, cascading trout streams. Though fond of shadow, it seems to grow equally well where the narrow canyons widen and admit the sunshine upon the tiny meadows of lush grass, cranesbill, velvety red cinquefoils, lupines, and yellow columbines. And when one of these miniature openings is fringed with spruces whose pointed tips rise sharp against a curtain of azure with its white cumulus clouds, there you have the loveliest vista in the mountains.

OUR VISIBLE IMPACT ON THE PLANT LIFE

Though nature lovers usually find the life zones more fascinating than any other aspect of plants in the mountains, there is one other much more important. It is the misuse, injury, and destruction of native plant life. Because scientists are generally alert to the conservation of what is useful and beautiful in natural resources, I venture to bring up the matter here.

A useful case history is provided by Silver City, New Mexico. It was founded in the early seventies as a silver camp, which would fairly guarantee a certain amount of reckless haste and rowdy carelessness. Point two was its location on a foothill watershed only twenty-seven square miles in area. Point three was an extreme concentration of livestock near the town. Point four was the fact that the annual rainfall was crowded mainly into July, August, and a part of September.

Mines are naturally users of timber. Obviously, shafts and tunnels have to be timbered. More than that, little smelters nestled back among the hills were also hungry for wood. And since coal was expensive and hard to get, most of the adobe cottages were heated many years by juniper, oak, and piñon firewood. All these matters were naturally, if not actually, inevitable under the circumstances.

The massive ore wagons and freight wagons had to be drawn by four- to ten-horse teams—and the horses kept on eating. Then because it was also a ranching country, each cowboy had to keep a _remuda_ of saddle horses—and they ate too. Also, the few cows that provided milk for the children grazed hungrily over the stony slopes. Most of all, the range cattle, which had no provender at all except that which the competitive, half-starved steers could provide for themselves, overgrazed every square foot of pasturage down to the bare soil. The government’s open-range policy made overgrazing inevitable because no ranchman could protect his pasturage since it was all unfenced. The cow that got there first got the grass. That passed as land management, which proves that some statesmen then were about as wise as some of the Wizards of Washington now. But the advent of fences caused the cutting of millions of fence posts where none should have been cut.

When the grass went, its roots went, and when its roots went, there was nothing to hold the soil, and then it, too, started to go. And go it did. A deep hole formed in Main Street, as it is still called on the Silver City town plat. The best explanation I can find of that hole is that earth was taken out of it to form adobe bricks for the walls of houses and corrals (that clay did make good adobe!). Meanwhile, the woodhaulers’ wagons had greedily carted away the trees from each little canyon, while the narrow steel tires cut deep ruts which formed two deep gullies at the first heavy rain. Then the parallel gullies proceeded to wash out deeper and create a middle ridge or high center on which axles got stuck. Since there was nobody responsible for making a new road, there was no choice except to move over and form another track and use it until in turn it became unusable. (By this simple kind of destruction, the old Santa Fe Trail, it is said, reached a width of a hundred feet.)

But the water descending the slope kept increasing its destructive velocity as the denuded ground approached the bareness of a tin roof. Villagers observed that the hole in their Main Street was becoming a waterfall after each rain, and that the ruin was passing into a big-time operation. The town built a dam to restrain the floods. It washed out in the first one. Soon Main Street followed it down the drain, which by this time was already a hideous gash in the earth many miles long and twenty feet deep. Then the water began on a really different scale of destruction. One furious flood washed away the cabin in which Billy the Kid’s mother lived. More than that, it washed away the wall of Judge Newcomb’s house and abducted his Steinway from the second floor. A few yards from the spot, an old photograph taken in 1891 shows a woodhauler’s ox team lying in the street there. It gives no hint at that time of the famous Big Ditch—the only name that Main Street, Silver City has had now for the last forty years.

By 1927, after many other attempts had been made to tame the floods a steel bridge about one hundred feet long and thirty feet above the floor of the “canyon” was swung into place. In 1935-1936, the Soil Conservation Service went to work in earnest, made the watershed a demonstration area, and spent a third of a million dollars there in a short time.

In the _New Mexico Magazine_ for August 1934, the really incredible story of the Big Ditch is exactly documented with old photographs and newspaper clippings. After a friendship of many years with old-time miners and ranchers at Silver City, I would not point an accusing finger at one of them. I appeal, however, for a greater vigilance over plant life and soils nowadays from everybody. In such protected areas as the Fort Bayard Reservation, the U.S. National Forest enclosures, and the frontier cemeteries, the imagination can visualize a New Mexico that is far different from what is here today—a close-picked, hard-used land where unwise woodcutting has continued through much of the last three centuries and where the thin ranges have been required to support in the last century alone perhaps more than one hundred million cows, sheep, and horses. The magnitude of the cause accounts for the magnitude of the effect.

A good many years ago, I wrote as the concluding paragraph to _Sky Determines_ what seemed to some exaggerated praise for my adopted homeland. There is now less and less cavil from any readers. I believed the words true in 1934, and I stand my ground now.

Perhaps nowhere in the world is the natural setting nobler than in New
Mexico—more beautiful with spacious desert, sky, mountain; more varied
in rich, energizing climate, more dramatic in its human procession,
more mellow with age-old charm. Endowed with sunshine that stimulates,
and winter chill that toughens; with silence and majestic desert color
that offer a spiritual companionship, it has enough. Here, if anywhere
is air, earth, sky fit to constitute a gracious homeland, not alone
for those who study and create, but as well for those who play, for
those who sit still to brood and dream.

This large ruin in Bandelier National Monument lies along the banks
of El Rito de los Frijoles. Narrow-leaf cottonwoods line the stream,
and shrubs of the Upper Sonoran Zone cover the hillside slopes.]

Dwellers in the Hills and Plains

_by_ Levon Lee[1]

The vast sweep of New Mexico’s 77 million acres, which ranges all the way from the Alpine tundra of the tallest mountains down to the heat of the lower Sonoran desert, offers a home and sanctuary for many kinds of wild life.

Some of these animals are considered game animals; others may be pests, since they prey upon or destroy what mankind regards as its own. The coyote which takes a sheep from the small herder is wicked indeed in the eyes of the sheepman. Predatoriness on all living things by other things has gone on since time began and will continue—mankind being not the least predator.

A good definition is that composed by the late Judge C. M. Botts who defined a predator as “a critter that takes another critter that I want.”

New Mexico’s immense topographic and geologic differences make for a very wide range of habitats preferred by the various species. The elk and deer, being highly adaptable, may be found from the Alpine tundra of the higher mountains clear out into the creosote desert. Deer occur in four separate subspecies: the Rocky Mountain and the desert mule deer, the western whitetail, and the Sonoran fantail deer, which is also a whitetail. These animals may be found all the way from the dense coniferous forests of the north with perpetual gloom and cold to the sun-scorched granite mountains such as the Florida and the Organ mountains of southern New Mexico; from great towering granite spires to the folded blocks of limestone such as comprise the Big Hatchets, the Guadalupe, and the San Andres mountains.

The javelina, or little wild pig, lives along the watercourses in the south west part of the state. Its thin spiky hair gives it little or no protection against cold, and only in the balmier parts of New Mexico does it feel at home.

The desert bighorn sheep, as distinguished from his cousin the Rocky Mountain bighorn, goes around on a sun-scorched, ocotillo-covered limestone-rubble slope in the full glare of the sun and lies down to take his afternoon siesta. The Rocky Mountain bighorn, on the other hand, with his preference for cooler climates does not shun even the dense spruce timber at the very top of the Sandia Mountains as the hideout for his afternoon rest.

This adaptability by New Mexico’s species to the tremendous differences in altitude, rainfall, and temperature makes them all the more valuable as a resource for the pleasure and enjoyment of everyone.

The most popular big game animals in New Mexico are the mule deer in either of the two subspecies. Every fall, beginning in late October and extending ordinarily through December, more than 100,000 hunters take to the woods for their 50-50 chance of bringing home the sought-after mule deer. A hunter may shoot his mule deer at the Alpine tundra timber line, out in the blazing heat of the creosote desert, or among the rock crags of some of the southern desert mountains. He will find his quarry a worthy opponent. Shy, wild, and with terrific eyesight and hearing, these animals provide a true challenge.

Elk and antelope, as well as bighorn sheep, are hunted by special licenses only, since their numbers do not warrant a general open season. These special licenses are much sought after and are ordinarily made available by application and a public drawing in the fall. The javelina, confined to our southwestern counties, is also hunted by special license. It is noteworthy that although New Mexico had protected them for many years, the javelina did not increase its numbers. As a matter of fact, the natural losses applied against any game species are going to be in effect no matter whether hunting is permitted or not, the hunting being merely subtracted from what would be lost to nature anyhow.

Our state mammal, the black bear, is found throughout the wooded areas of the state and occasionally wanders out into the plains or down into the desert mountains of the south. Bears are hunted avidly in the fall by sportsmen with dog packs before the regular big game seasons begin, when the use of dogs is prohibited. They are again hunted during the big game seasons by anyone bearing the proper license, but no packs of dogs are allowed. This is to prohibit the possibility of dogs being used to pursue elk, deer, or wild turkey, an illegal act in New Mexico.

New Mexico is fortunate in having a tremendous diversity of both upland game and waterfowl, and big game and small game for her people. Importantly, the game resources are spread out through every county in the state.

The state’s richness of bird life is varied and extensive. New Mexico ranks among the first five in the total number of birds found within its boundaries. More than 400 species of birds live within the state. These range all the way from the tiny mites of the bird kingdom, the hummingbirds, weighing less than an ounce, to the great white whistling swan, weighing up to 25 pounds, or the Merriam turkey, which may weigh close to 30. Of the six species of quail found in the United States, New Mexico has four and may possess the fifth, since the mountain quail of the western coast have been introduced into this state and still occur on the west slopes of the Sacramento Mountains near Tularosa. Five species of doves found throughout the state from the highest coniferous forest down into the scorching heat of the creosote desert are the Inca dove, ground dove, mourning dove, white-winged dove, and the bandtail pigeon, all of them close relatives. Of these, only two, the mourning dove and the white-winged dove, are commonly hunted as game species.

An unexplained and precipitous decline struck the bandtail pigeon about ten or twelve years ago, from which it apparently has never recovered. Although hunting was undoubtedly part of the pressure exercised against these birds, it in no way accounted for their sudden and dramatic decline in numbers. This decline may gradually be reversed, since more and more of these birds are being seen. It is well known that animals with a high reproductive capacity can endure much heavier losses to their population than can those with low or very limited reproduction, such as the bandtail, which normally lays only a single egg. The mourning dove, on the other hand, lays two eggs at a time and may raise as many as five or more broods in one year. Take this one step further with the scaled or Gambel quail, which may lay up to 12 or 15 eggs, and it can readily be seen that the population of bandtail pigeons can never endure the losses that the much more prolific mourning dove and quail can. The same might be said by comparison of elk and deer. Elk do not bear their first young until their third year, and then the cow may not bear young but alternate years until her seventh or eighth year; by that time she has begun to decline in vigor; in her total life she may not produce more than four or five calves. The mule deer, on the other hand, start bearing at the age of two, with their first birth normally single; from then on, twins are usual for the rest of the doe’s life. Thus, deer have a considerably greater reproductive potential than do elk or bighorn sheep, which have one young at a time.

The fleet-footed antelope of the open rolling plains is another example of fairly high reproductive capacity, since they breed earlier than do deer and normally bear twins. Antelope are confined to the more open country where their prodigious running ability and marvelous eyesight stand in good stead in protecting them against their natural enemies.

The wild turkey, classified by law in New Mexico as big game, is found throughout the mountainous areas of the state, not excepting some of the desert ranges. New Mexico is one of two states fortunate enough to possess three of the five forms of the wild turkey known to the United States: the Merriam turkey, found in the higher elevations of the mountainous areas, usually the ponderosa forest; the Rio Grande turkey, confined to the watercourses of the eastern plains; and the fairly rare Mexican turkey, found in the Animas and Peloncillo mountains of extreme southwestern New Mexico. In Hildalgo County these mountains are actually largely Mexican in both flora and fauna. Some of the rarest, most beautiful birds of North America are also found in this area and nowhere else in the United States with the exception of southeastern Arizona.

Our most abundant game bird, the mourning dove, is found in every county of the state and nests from the coniferous forests of the north and the higher mountains of the south clear out into the plains where there is not a tree in sight for miles. Doves are extremely adaptable and very prolific. They provide the finest kind of sport shooting and are avidly sought, particularly by shotgun enthusiasts of the eastern and southern parts of the state.

Scaled quail are found throughout New Mexico, being absent only in elevations above 7000 feet. Even there, they periodically occur but are ordinarily driven back by winter snow. Gambel quail are found throughout the river courses of the Rio Grande Valley, the San Juan Valley, and the southwestern watercourses. The Mearns’ quail is found in the southern half of the state in the higher mountain elevations, whereas the bob-white quail occupies the grassy rolling sandhills of the eastern counties where it is commonly found together with scaled quail.

Quail hunting is one of the most popular sports in New Mexico and many thousands of hunters can hardly wait from one season to the next. New Mexico is in the heart of the scaled quail country and provides some of the finest shooting to be had anywhere.

Migratory waterfowl, while not considered abundant, are not uncommon in this state, known more for its aridity than for its rivers and lakes. The two main fly ways are the Rio Grande Valley and the Pecos Valley, with the Pecos Valley being somewhat ahead in total numbers.

Ducks commonly found in New Mexico in abundance are teal, both green-winged and blue-winged as well as the lesser-known cinnamon teal, mallards, widgeon, pintails, gadwall, scaups, canvasbacks, redheads, and other species.

In addition, New Mexico plays winter home to many thousands of the lesser sandhill crane which is confined to the river valleys and open plains of the eastern part of the state, particularly the southeastern counties. A smaller population of the greater sandhill crane is found in the Rio Grande Valley and near Columbus. Flocks of the small Richardson’s goose are found in the northeastern counties, in particular, and along river courses throughout the state. The small snow goose is likewise confined mostly to major river courses. The larger Canada geese are found particularly in the middle Rio Grande Valley where extensive development has been made by both state and federal agencies to encourage the use and the presence of bands of geese.

New Mexico is unique in that it was the first state in many years to be able to open a hunting season on the lesser sandhill crane. This bird is comparatively abundant, the total population probably being in excess of 200,000, with the vast majority of these birds wintering in west Texas, New Mexico, and Mexico. They occasionally cause heavy depredation to grain crops in the southeastern part of the state, and hunting has been partly justified on the basis that the large wintering flocks might be broken up and depredation spread over a larger area for less individual effect. These birds are tall, wild, and shy. They are hard to hunt, even more so than geese, and although strenuous efforts have been made, not too many of them are bagged.

One should not overlook the tremendous opportunity for sport hunting of unprotected species, such as the various rabbits, the mountain lions and bobcats, and coyotes.

The wolf is now very rare in New Mexico. Only occasionally do wolves come out of Mexico into the southwestern counties, usually in Hidalgo, Luna, and Doña Ana. Wolves are large, effective predators and are incompatible with the cattle-raising industry. Since they have a fondness for beef, the hand of the cattleman is raised against them.

The mountain lion prefers his natural prey of deer, mule deer being the principal victims. The bobcat preys on deer and on many of the small wild animals, rabbits in particular. These predators, when run and hunted with a pack of dogs, provide a fascinating sport which is growing in popularity.

The use of calls to attract animals to a “victim” has become widespread. The calls imitate the distressed cry of rabbits and other creatures which to the predator means a meal close at hand. Everything from mountain lions to red-tailed hawks have been hunted by this procedure, and it can be very successful in bagging quarry. This type of hunting has value in that it can be enjoyed at any time of the year throughout the state and with a minimum of time and effort.

Hunting is a conservation practice that, wisely administered, results in wholesome out-of-door recreation and brings many tons of high protein food of highest quality to the table. Nature nowhere in her economy locks up a resource and throws away the key—we should be no less wise.

Long gone are the buffalo which once roamed the High Plains of eastern New Mexico. Exotic animals, imported and stocked along the rugged canyon of the Canadian River above Conchas Reservoir, are the Barbary sheep with their magnificent coiled horns. Beavers dam some of the mountain streams, badgers and skunks can be seen from the highways, and amid the forests are squirrels and porcupines, while high on rock slopes, the Rocky Mountain woodchuck and the gray rock cony dash from ledge to ledge. The white-tailed ptarmigan also haunts these high crags, and lower down the mountain, bluebirds nest. Hawks, eagles, magpies, jays, ravens, orioles, wrens, sparrows, warblers, finches, and many other birds of endless variety soar over canyon, forest, and sand-dune desert.

Most notable of all is the crested roadrunner, the chapparal cock or paisano of Mexico and the state bird. In between racing with horsemen or automobiles, the slender roadrunner cocks his head, strikes swiftly and victoriously, then swallows his victim, which can be a small rattlesnake, whole.

Snakes there are aplenty. Mostly, they are nonpoisonous, such as the garter snake, glass snake, puff adder, ring-necked snake, the coachwhip, the Mexican blacksnake, and the large western bullsnake. The small but very venomous coral snake is rare, but common among rocks and near streams are the large western diamondback rattlesnake, the prairie rattlers, and the less common green or blacktailed rattlesnake. Every sun-warmed rock has its scampering lizard, and nearby are horned toads, dry-land terrapins, tortoises, tarantulas, centipedes, vinegarroons, scorpions, and spiders. Of these latter desert animals, only the black widow spider is poisonous.

Contrast in the influence of environments is shown by the animals that inhabit the “malpais,” the recent flows of black, rough-surfaced lava, compared with similar animals found among the white gypsum dunes of White Sands. Black or darkly colored subspecies of mice, plains wood rats, kangaroo rats, and rock squirrels live on the black lava, whereas white or pale counterparts of these animals live among the white gypsum dunes.

The dwellers in the hills and plains of New Mexico are as varied as the hills and plains; they add their color and movement to the scenes of the Land of Enchantment.

Rocks That Shape the Enchanting Landscape

_by_ Frank E. Kottlowski

“As old as the hills.” How much more ancient can anything be? Yet New Mexico’s hills, its enchanting landscapes, were built in but the most recent “minute” of geologic time. Merely one geologic era ago, marine waters covered the state, and storm-tossed waves ruled where now the hot sun beats down on dry sands and cacti a mile above sea level.

What determined the Land of Enchantment’s landscapes? Shaping these land forms are the rocks of the earth’s crust, the structure of those rocks, and the endless battle between the rocks and the atmosphere. A story spelled out in stone, the geologic history. The rocks determine.

Eons ago, it began; one billion, two billion, or perhaps even more billions of years ago. A history whose beginnings have been lost owing to destruction of its earliest records. A history, written in the rocks, that is divided into four general parts (fig. 1). The oldest rocks, more than 600 m.y. (million years) old, almost devoid of traces of life, are the Precambrian rocks. The Paleozoic rocks, 230 to 600 m.y. old, are marked by ancient (_paleo_-) life. This was the Period of Invertebrates, animals without backbones. Mesozoic rocks, 70 to 230 m.y. old, formed in the Era of Dinosaurs and contain types of life that are intermediate (_meso_-) between the ancient and modern animals. And rocks of the Cenozoic Era, 70 m.y. ago to the present, make up the latest (_ceno_-, recent) chapter of the earth’s history.

Events of the Cenozoic Era have had the greatest influence on New Mexico’s landscapes. So let us begin the story at the dawn of the Cenozoic, and return to the earlier geologic chapters later.

CENOZOIC ERA

The mountains, the plains, the rivers, and the lakes all are transitory features of the landscape, created during the recent part of the Cenozoic Era, and all doomed to destruction in the near future, geologically speaking. Even so, some of the plains and mountains may predate man’s evolution onto the earth scene.

Gone were the late Mesozoic seas; never again during our lifetime nor the lifetime of many future generations will marine waters roll over New Mexico, and sea-spawned creatures rule. For the first two thirds of the Cenozoic, the Paleogene Period (25 to 70 m.y. ago), New Mexico suffered from the dying effects of the great Laramide upheaval of the earth’s crust. Large areas were exposed to the harsh erosion of stream and wind. The landscape looked as parts of southwestern New Mexico do today—tall rugged mountain ranges scattered in isolated patches amid wide gravelly plains. But the climate was more humid, and while no large through rivers are known, local great swamps and lakes lay on the plains in debris-trapping lowlands.

_Scale of geologic time
in millions of years_
_Era_ _Rocks_ _Dominant life_
_Geologic age_

70 CENOZOIC
Neogene
Pleistocene Bandelier volcanic ash, Man
basalts, sand dunes, river
gravels, glacial & lake beds.
1 my
Pliocene Volcanic rocks of Mt. Mammals
Taylor, early Valle Grande &
Gila region; Santa Fe, Gila,
and Ogallala Fms.
11 my
Miocene
25 my
Paleogene
Oligocene Datil, Espinaso, and other
volcanic rocks.
40 my
Eocene Baca, Animas, Nacimiento,
San Jose, Raton, Poison
Canyon, Galisteo El Rito,
Blanco Basin, & Cub Mountain
Fms.
60 my
Paleocene
160 MESOZOIC
Cretaceous Upper sandstone, shale, & Dinosaurs
coal. Mesaverde, Pierre, &
Niobrara, Dakota Ss. and
Mancos Sh.
Volcanic rocks, limestone,
sandstone, and conglomerate.
135 my
Jurassic Morrison Fm., Summerville
Fm., Zuni Ss., Todilto Ls. &
gypsum, Entrada Ss.
180 my
Triassic Wingate Ss., Dockum Fm.,
Chinle Fm., Santa Rosa Ss.,
Moenkopi Fm.
370 PALEOZOIC
Permian Rustler Dolomite; redbeds Amphibians
Castile gypsum, Salado Salt.
Artesia Grp.—Capitan reef
San Andres Ls.—Goat Seep reef
Glorieta Sandstone
Yeso Fm.—Bone Spring Fm.
Abo Redbeds—Hueco Ls.
280 my
Pennsylvanian Mostly limestone; beds of
shale & sandstone; lenses of
gypsum, salt, and coal.
310 my
Mississippian Helms & Paradise Fms. Fish
Rancheria Ls.
Lake Valley & Escabrosa Lss.
Arroyo Penasco & Tererro Fms.
345 my
Devonian Percha Shale, Ouray Ls.
northern dol., ss, and sh.
erosion
400 my
Silurian Fusselman Dolomite
erosion
425 my
Ordovician Montoya Dolomite Invertebrates
El Paso Limestone
Bliss
500 my
Cambrian Sandstone
erosion
1500+
PRECAMBRIAN quartzite, gneiss, rhyolite, Simple
andesite, granite, primitive forms
pegmatite, schist,
greenstone.

Scenery in north-central New Mexico (fig. 2) may have been similar to today’s, with mountains in the same general areas as the present-day Sangre de Cristo, Nacimiento, San Juan, and Brazos ranges. Coarse-grained gravels were stacked up at the edges of the mountains, but out in the adjoining lowlands, floodplain sands and varicolored lake-bed clays settled. Three low areas were “basins” of deposition where thick masses of sediments accumulated—the Raton and Poison Canyon formations in the Raton Basin near Raton, the Animas, Nacimiento, and San Jose formations in the San Juan Basin north and northwest of Cuba, seen along N.M. Highway 44, with thinner deposits of the El Rito and Blanco Basin formations to the northeast of Cuba, and the Galisteo Formation in the Galisteo Basin south and southwest of Santa Fe. Volcanic rocks, the Espinaso beds, overlie the Galisteo but are not much younger in age. Reddish rocks of the Galisteo Formation crop out along U.S. Highway 85 at La Bajada Hill about twenty miles southwest of Santa Fe. The Sandia Mountains’ area appears to have been a lowland.

Silicified wood, chiefly of pines but with some oak and poplar, is abundant in the Galisteo Formation. Large logs, up to 6 feet in diameter and 135 feet long, have been found. In the great swamps of the Raton Basin, where the climate was much like that of Georgia today, tall reeds, water lilies, fig trees, palm trees, magnolias, and sycamores grew in profusion, and contributed to the thick coal beds now mined there. The early ages of the Cenozoic saw the spectacular rise of the mammals to dominance over reptiles on land; numerous remains of the early mammals are found in the Nacimiento and San Jose formations, including the famous Puerco and Torrejon faunas—as well as many clams, snails, fish, turtles, crocodiles, snakes, and birds.

Southeastern New Mexico appears to have been relatively level with only local hills and vast regions of featureless, stagnant but high plains where erosion slowly ate downward, deposition was slight, and most of the detritus was carried eastward far beyond the state’s borders. The redbeds of the Baca Formation were laid down on the north flank of low mountains that extended intermittently from somewhere near Quemado toward Socorro. Some ancient hills near present-day Sierra Blanca shed rock fragments that accumulated near Capitan as the varicolored Cub Mountain Formation. Deeply eroded uplands northwest of Elephant Butte Reservoir supplied gravels and sands that mingled with andesitic volcanic debris as the upper part of the McRae Formation in central Sierra County. Many of the weathered greenish and purplish volcanic rocks in southwestern New Mexico were extruded at this time, and beneath the surface these molten magmas (hot liquefied rocks) cut into older rocks. Vapors and hot solutions from the magmas are believed to have emplaced some of New Mexico’s vast ore deposits during this time.

The last phase of the Paleogene Period, about 25 to 40 m.y. ago, was an earth-shaking time in New Mexico—and the first explosion of an atomic bomb in 1945 on the Jornada del Muerto between Socorro and Carrizozo was a relatively low-energy-yield event compared with the late Paleogene earth movements. Almost the entire southwestern quarter of the state literally exploded, with volcanic eruptions on a grand scale. These lava flows, rock breccias, ashes, pumice, and associated intrusives (molten rocks that did not make it to the surface) form the Datil-Mogollon plateau—at least 100 miles in diameter—as part of the Datil Formation, which locally is miles thick, and made up the main mass of many other ranges near the Mexican border. Sierra Blanca (12,003 feet altitude) northeast of Alamogordo is a huge, isolated volcanic mass of late Paleogene age.

This widespread volcanic activity continued into the Neogene Period which began about 25 m.y. ago. Rhyolites, pumice, and perlite in the southwest, as well as in other parts of the state, covered wide areas. Mount Taylor, towering up to 11,389 feet near Grants and visible on the western skyline from Albuquerque, is a Neogene volcanic pile, as are parts of the Sangre de Cristo range northeast of Taos. Shiprock and Cabezon Peak, landmarks in northwestern New Mexico, are volcanic necks—the eroded cores of ancient volcanoes.

Valle Grande caldera makes up the center of the Jemez Mountains west of Los Alamos and is a late Neogene volcanic mass with the central crater sixteen miles in diameter—one of the world’s largest calderas. Bandelier National Monument headquarters is within a canyon carved from Valle Grande’s ashes. Volcanic ash scattered over the western parts of Texas, Oklahoma, and Kansas was blown from this volcano. Capulin Mountain, east of Raton, is a huge recent cinder cone and is surrounded by numerous basaltic lava flows that cap the High Plains from Raton eastward to Clayton. The very fresh black basalt flows near Carrizozo and in the valley of Rio San Jose near Grants are probably less than 1000 years old. Numerous mesas along the Rio Grande Valley from the Colorado line to El Paso are capped by black basalt flows of late Neogene age.

Many of the present-day mountains were uplifted in early Neogene time, following the climax of the great volcanic eruptions. This uplifting, in many instances, took place along one side of huge mountain masses, forming tilted fault blocks like the Sandia, Manzano, San Andres, and Sacramento mountains. Rock beds in the Sandia Mountains, for example, dip to the east, but were uplifted along a west-bounding fault zone—a huge break in the earth’s crust—as much as four miles! This was an earth-shaking event! However, the uplifting took place slowly, and indeed is continuing today as the Albuquerque area, along with the Rio Grande Valley southward to Socorro, is one of the most active earthquake areas in the state.

Concurrent with uplift, other blocks of the earth’s crust sank, forming graben basins which were flooded with rock debris from the adjoining uplifts. A tremendous irregular graben, now followed by the Rio Grande, cut north-south across the state. Geologists label it the _Rio Grande structural depression_ (fig. 3). Mountains on the east are the Sangre de Cristo, Sandia, Manzano, Los Pinos, Fra Cristobal, and Caballo ranges; those to the west include the Brazos, Jemez, Ladron, Socorro, Magdalena, and San Mateo mountains. Within this complex graben, and around the bordering ranges, the colorful sandstones and siltstones of the Santa Fe Group were deposited—these red, yellow, orange, and cream rocks are eroded in many places, such as near Santa Fe, to “badlands” characteristic of the landscapes along the Rio Grande Valley from Espanola southward to El Paso. Much brightly tinted silicified wood is found in these beds, and literally freight-car loads of mammalian remains have been shipped to museums from outcrops near Espanola.

In the basins amid the mountains of southwestern New Mexico, similar sands and gravels of the Gila Conglomerate filled low areas. East of the mountains of central New Mexico that form a north-south chain of ranges from Raton to Carlsbad, thin gravels of the Ogallala Formation were dumped onto the western edges of the High Plains. They now cap the plains as well as make picturesque bluffs east of the Pecos River and southeast of Tucumcari—the “caprock” of that area. In northwestern New Mexico, isolated mesas are topped by the Chuska and Bidahochi formations; similar sands, silts, and clays washed from adjoining highlands.

The final episodes of landscape formation occurred during the Pleistocene Epoch, the recent glacial period. Mountain valley glaciers occupied some of the higher parts of the state, as far southward as Sierra Blanca; large lakes filled many of the closed basins, such as those near Estancia and south of Lordsburg; the Carrizozo and Grants basalt flows were extruded; the final tremendous explosions of Valle Grande spread volcanic ash over large regions; sands, gravels, and clays were eroded and deposited by streams and in lakes; and sand dunes were heaped up in many areas. The glistening white gypsum dunes (fig. 4) of White Sands National Monument, built up into 50-foot-high mounds windward of gypsiferous Lake Lucero, are spectacular products of the wind.

The Rio Grande, in its present valley, probably is only as old as mid-Pleistocene, born during late uplift of its headwater mountains, the San Juan and Sangre de Cristo ranges in southern Colorado and northern New Mexico—initiated by floods of meltwaters from waning mountain glaciers. Some of the lower terraces (benches) along the Rio Grande are very young, being dated by radiocarbon methods at 2600 b.p. (before present). Until shackled by Elephant Butte Dam in 1916, and smaller dams up and down the valley, the Rio Grande switched its course with every large springtime flood. Even with these man-made controls, the Rio carves new channels during floods and covers flooded fields with silt as the high waters recede.

PRECAMBRIAN ERA

The highest points in New Mexico are in the north-central region. Here, along the backbone of the Sangre de Cristo Mountains, tower Wheeler Peak (13,160 feet above sea level), northeast of Taos, and South Truchas Peak (13,102 feet), northeast of Santa Fe. Snow lingers on these lofty spires all year around except during an especially hot August. Highest peaks—they must be capped by the youngest rocks. But no, the quartzites and gneisses, hard rocks made up of quartz and feldspar, that hold up these pinnacles against the attack of water and ice are among the oldest rocks known in the Southwest—perhaps as much as two billion years old. These Precambrian rocks lay deep beneath the earth’s surface from early Paleozoic time (500 m.y. ago?) until early Neogene time, then were uplifted along great breaks in the earth’s crust, uplifted slowly and intermittently during the span of time from about 20 m.y. ago to perhaps 1 m.y. ago.

How did these ancient rocks form? What did New Mexico look like during the dawn of geologic history? The record in stone is fragmentary. But about two billion or so years back, thick masses of quartz sandstone were laid down in north-central New Mexico, as well as vast lenses of mud, and some beds of feldspar-rich sandstone. Volcanic activity was intense; huge flows of rhyolite and andesite were poured out over most of the state, and these in turn, along with the muddy and sandy sediments, were intruded by enormous masses of hot granite. Mile-high mountains were formed, and during the stretch of this early geologic time, called the Precambrian Era, the high peaks were eroded by rain, wind, and sun until some were worn down to featureless plains sloping toward the ancient ancestral oceans.

These Precambrian rocks now make up the cores of such mountain ranges as the Sandias east of Albuquerque, the Sangre de Cristo range near Santa Fe, the Pedernal Hills south of Clines Corners, the Burro Mountains southwest of Silver City, the Brazos Range east of Tierra Amarilla, the Zuni Mountains southwest of Grants, and the San Andres Mountains west of White Sands. As seen in Tijeras Canyon east of Albuquerque, the bulk of the ancient rocks are gray to pinkish granite and granite gneiss, speckled by crystals of biotite, microcline, orthoclase, and quartz. Quartzites (hardened sandstones), greenstone, and foliated mica schists (fig. 5) are the older rocks that were intruded by granitic magmas about 1350 million years ago—as indicated by dating of radioactive isotopes, K-Ar and Rb-Sr. Locally, pegmatite dikes, a late-cooling, large-crystal stage of the granites, crisscross the granite and contain excellent crystals of quartz, feldspar, and mica, as well as less common minerals. The famous Harding pegmatite near Dixon, about forty miles north of Santa Fe, contains beryl, columbite-tantalite, lepidolite mica, spodumene, and other rare minerals. Some of these crystals are ten feet in length!

PALEOZOIC ERA

There are some primitive types of plant and animal life known from Precambrian rocks outside of New Mexico but the earliest beds that contain abundant fossils are those of Cambrian age, 500 to 600 m.y. old. Cambrian rocks in New Mexico are in the Bliss Sandstone, a reddish brown iron-rich bed, 50 to 200 feet thick, that occurs only in the southern part of the state. There it can be seen, for example, along the bold east-facing escarpment of the San Andres Mountains or the west-facing cliffs of the Caballo Mountains, as a dark band resting on the pinkish Precambrian granitic rocks. It is a shallow-sea sand, deposited on the northeastern edge of the Cambrian seas. Scattered amid the brown-stained quartz, red hematite, and green glauconite are broken shells of trilobites and primitive brachiopods. Northern New Mexico was a low, broad island during Cambrian time, a source of some of the sands in the Bliss Sandstone.

During the Ordovician Period, 425 to 500 m.y. ago, upper sands of the Bliss as well as overlying limestones and dolomites were deposited in the shallow warm seas of southern New Mexico; these latter rocks are the El Paso Limestone and Montoya Dolomite. The Ordovician seas teemed with invertebrate life. Fifteen-foot-long cephalopods, as much as a foot in diameter, ruled the shallow salt-water bottoms, munching on the abundant trilobites and the moss animals, the bryozoans. Numerous brachiopods, corals, snails, and clams also thrived, with many of the Ordovician carbonate-rock beds literally being made up of these fossil remains. Near El Paso, these limy fossiliferous beds are nearly 2000 feet thick, but they thin northward to a knife edge in thickness near Mockingbird Gap at the north end of the San Andres Mountains. Parts of northwestern New Mexico may have been low islands exposed to the sun and erosion during Ordovician time, but most of the state was probably within an extensive shallow ocean. Later, erosion removed the Ordovician rocks from central and northern New Mexico.

Silurian strata, the brown Fusselman Dolomite, deposited during the middle of that period (400 to 425 m.y. ago), remain only in the southern and southeastern parts of the state, thinning out northward from the 1000-foot-thick bed near El Paso. The extent of these middle Silurian seas is not known, but most of central and northern New Mexico was undergoing erosion during late Silurian time. The northward thinning of the Fusselman Dolomite is due chiefly to this erosion, evidenced by the knobby, ridged and channeled top surface of the Fusselman. Brachiopods and corals are the most abundant fossils in the Fusselman Dolomite; elsewhere, Silurian rocks are known for the sea scorpions or eurypterids, which attained a length of nine feet, and for the complete remains of primitive fishes.

During early and middle Devonian time (345 to 400 m.y. ago), most of New Mexico was a lowland rotting beneath the sun. Fossiliferous Devonian rocks are unknown in the north-central part of the state but occur beneath the surface in the Four Corners region of northwestern New Mexico and the adjoining states. These rocks are of late Devonian age and consist of lower dolomite and sandstone, middle shale and dolomite, and the upper Ouray Limestone.

In southern New Mexico, a uniform blanket of dark limy muds, called the Percha Shale, was deposited during late Devonian time. This shale marks a great change from the limestones of earlier ages. In part, it is of black muds deposited in widespread or in local stagnant basins and in part calcareous fossiliferous muds in which abundant invertebrate life was buried. The clay and quartz silt that make up the rocks were a weathered residuum that had accumulated, during the long period of late Silurian and early and middle Devonian times, on the lowland of central and northern New Mexico.

Except in the stagnant basins, invertebrate life was prolific, brachiopods, bryozoans, and corals being especially numerous. Fossil fish remnants, chiefly teeth, are abundant in some of the sandy units, and outside of New Mexico the earliest amphibians occur in upper Devonian rocks. The oldest definitely known assemblage of land plants occurs in the Devonian, and forests containing forty-foot-high trees spread over the uplands. Such tree ferns, horsetail rushes, and lycopods (spiked-leafed trees) may have grown in profusion on the swampy lowlands near Albuquerque’s and Santa Fe’s present sites, far north of the muddy Devonian seas of southern New Mexico.

Figure 6. Fossil specimens

Mississippian rocks (310 to 345 m.y. old) probably were deposited over most of New Mexico. Subsequent erosion removed much of the Mississippian beds in northern New Mexico. The remnants, less than 100 feet thick in most places, are of lower sandy and shaly beds overlain by massive crinoidal limestones, the Arroyo Penasco Formation of the Nacimiento and Sandia mountains and the Tererro Formation of the Sangre de Cristo range east of Santa Fe.

In southern New Mexico, the Mississippian beds are thick and widespread, being more than 1000 feet in thickness in the southwestern panhandle. There the rock units are the Escabrosa Limestone of the southwest or the Lake Valley Limestone of the south-central part of the state. These are massive fossiliferous limestones precipitated in shallow extensive seas abounding with invertebrate life. Huge gardens of the sea lilies, crinoids, spread over the area, their remains mingled with those of lacy moss animals, the bryozoans, and with brachiopods and corals. Locally, as in the region of the Sacramento and San Andres mountains and Black Range, moundlike fossil reefs, called bioherms, were built. Some of these bioherms in the Sacramento Mountains are mounds of fossiliferous limestones 350 feet high and several thousand feet in diameter. Beds on their flanks dip as much as 35 degrees and are made up of broken “fossil hash” calcite sands. One can stand at the base of these huge limestone hills and almost hear the ancient waves breaking against the reef and see the dying struggle of the brachiopod (fig. 6) that left his shell in the reef-flank sands.

To the south, beginning near the present site of White Sands, dark cherty limestones were laid down in stagnant waters, to become the Rancheria Limestone. This black to reddish brown siliceous limestone is more than 300 feet thick near El Paso. There its thin beds break down into slabs that resemble a jumbled woodpile.

Northern New Mexico was above sea level during late Mississippian time; in some areas caves developed in the porous limestones, and in other places the limestones were eroded to a residuum of chert and red clay. The land must have looked like the karst areas of Indiana, Kentucky, and Illinois today—with lost rivers flowing into sink holes, numerous caves, and many underground rivers. Only the southernmost part of the state was awash in the late Mississippian seas, and in these salt waters, rocks of the Helms and Paradise formations settled. They are typical nearshore beds of yellowish limy sandstone, green limy shales, and brown sandy oolitic limestones. Plant fossils occur intermingled with marine animal remains; the plant fragments were washed into the shallow seas from the land areas of the central and northern parts of the state.

The Pennsylvanian Period (280 to 310 m.y. ago) was a time of change. Previously, northern New Mexico had been an emergent lowland or barely awash in shallow waters, while to the south shallow but extensive seas held sway, the spawning ground of the vertebrates and invertebrates that evolved between 310 and 600 m.y. B.C. But mountains were built during the Pennsylvanian, and the whole pattern of land and sea was altered. The sun rose on north-south aligned ranges interspersed with north-south-trending seas (fig. 7). Somewhere north of Albuquerque a mighty range of mountains, the Uncompahgre Range, arose to shed rock debris into adjoining ocean basins. To the southeast, a lower but prominent range, the Pedernal Mountains, stretched from the present-day Pedernal Hills southward to somewhere near Ruidoso and Piñon. Rocks eroded from this landmass were dumped westward into the Orogrande basin which occupied the region near the present-day White Sands; there as much as 3000 feet of beds accumulated—impure sandstones, dark shales, fragmental limestones, and even some gypsum during the end phase of Pennsylvanian sedimentation.

Rocks filled the Delaware basin in southeastern New Mexico—limestones, sandstones, and black shales that now produce oil and gas. In northwestern New Mexico west of Grants and mostly west of the Zuni Mountains, a low land area, the Zuni Islands, was the source of eroded residuum released into an ocean channelway that ran north-northwest through central New Mexico from El Paso to Farmington. And in the northeast, granite hills of the Sierra Grande Arch stood above the shallow Pennsylvanian seas.

In the Four Corners region, broken rock from the Uncompahgre Range was rushed westward into the Pennsylvanian-age Paradox Basin. Amid the clastic limestones, black shale, gypsum, and salt of this basin are oil-bearing lenses. Today, oil wells pump this black “gold” from the ancient rocks—wells almost in the shadow of Shiprock’s famous spire.

The Pennsylvanian Period was a time of coal making on the greatest scale in the earth’s history. Extensive swamps and marshes, the habitat of peat and ultimately coal, were almost lacking in New Mexico. Thus, only thin scattered lenses of coal occur in the Pennsylvanian beds of the state. The lands of this period were covered by tree ferns, scale trees, horsetail rushes, and primitive conifers. In the shallow seas, the dominant invertebrates were fusulinids (fig. 8), small-shelled protozoans shaped like grains of wheat. Abundant cockroaches, large dragonflies, and spiders swarmed over the land.

Permian Rocks

The Permian Period (230 to 280 m.y. ago) dawned with renewed rising of the highlands in northern New Mexico and southern Colorado. Floods of red sand and clay, washed from the rotting hills, wiped out the seas of northern and central New Mexico, and intertongued southward with marine limestones. These early Permian rocks are the Hueco Limestone near El Paso, there 2200 feet thick, the Abo Redbeds near Albuquerque, and the upper Sangre de Cristo Redbeds southeast of Santa Fe. Wherever the redbeds crop out, their dark reddish brown hue, speckled and striped with spots and streaks of green, enlivens the drab gray-and-brown landscape. Some of the reddish coloring is from angular grains of red to orange feldspar, but most is in thin brilliantly tinted skins of hematite that coat the sand grains and saturate the clays. In northern and central New Mexico, amphibians and other primitive vertebrate animals lived amid the red soils and sands; their bones and imprints have been preserved on thin flat slabs of sandstone that now decorate sidewalks and patios.

Figure 8. Fossil specimens

The early Permian seashore, where limy muds beyond the surf intermingled with red sandy muds swept from the north, vacillated somewhere north of Alamogordo with each sea-level change. Amid the breakers, and as submarine banks in the shallow waters, reefs grew—moundlike masses of shell debris and calcite mud trapped among frondlike calcareous algae. Near Tularosa, these algal “bioherms” are sixty feet high and extend within broad belts half a mile wide. In southeastern New Mexico, these buried “Abo” reefs have yielded much oil.

By the middle of Permian time, the southern Colorado mountains had been worn down to low hills that lay north of an extensive sea covering most of New Mexico. From Santa Fe south to White Sands and southeastward almost to Carlsbad, very shallow marine waters were alternately stifled by pale-red sandy muds or evaporated by the sun. The results were alternating beds of pale-red sandstone, gypsum, and silty dolomitic limestone, called the Yeso Formation. Locally, as near Carrizozo, thick deposits of rock salt also were precipitated, and the Yeso there is about 4000 feet thick. At this time, the Delaware basin of southeastern New Mexico saw the beginning of its most spectacular events, the building of the Capitan and Goat Seep reefs. This basin—a huge oval south of Carlsbad and east of Carlsbad Caverns—had been “deep” sea during most of Pennsylvanian time, but it was a more distinct geographic feature during the Permian. While the pale-red sands, gypsum, halite, and dolomitic limestones of the Yeso Formation were laid down to the north and northwest, the Delaware basin was rimmed by a low, broad bank of fossil-hash calcite sand, now called the Victorio Peak Limestone. In the basin, in deep stagnant waters, black sandy limestone and black shale of the Bone Spring Formation were deposited.

A sheet of white quartz sand filled the late Yeso seas; the resulting Glorieta Sandstone, about 200 feet thick, prominently caps Glorieta Mesa. Its cliffs are a familiar sight to travelers on the Santa Fe Railway at Glorieta Pass. The Coconino Sandstone in the Grand Canyon area of Arizona is the western part of the Glorieta. This “clean” sand—lacking intermixed mud—marks the continued lowering of the southern Colorado uplands. Broad seas then spread over all but northern New Mexico and a thick (600 to 1000 feet) persistent marine unit, the San Andres Limestone, was laid down. Much oil is produced in southeastern New Mexico from this dark-gray unit of limestones and dolomites. The rich agricultural region stretching from Roswell to Artesia depends on underground water gained from the San Andres Limestone, water that falls as rain and snow on the Sacramento Mountains, seeps underground into the cracks and caverns within the San Andres, and flows eastward downslope to the Pecos Valley.