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95-609: Most of the Caballo Mountains are located on land owned by the Bureau of Land Management . The mountains are unusual, and perhaps unique in New Mexico, for the relatively complete geologic history revealed by their rocks. Vehicular access to the range is by Interstate 25 from the west, by New Mexico State Road 51 from the north, and by several dirt roads from the east. The Caballo Mountains trend north and south, with

190-622: A cataclysm known as " The Great Dying ", the third and most severe Phanerozoic mass extinction. The early Cambrian climate was probably moderate at first, becoming warmer over the course of the Cambrian, as the second-greatest sustained sea level rise in the Phanerozoic got underway. However, as if to offset this trend, Gondwana moved south, so that, in Ordovician time, most of West Gondwana (Africa and South America) lay directly over

285-445: A foothold on land. These early plants were the forerunners of all plant life on land. During this time, there were four continents: Gondwana (Africa, South America, Australia, Antarctica, Siberia), Laurentia (North America), Baltica (Northern Europe), and Avalonia (Western Europe). The recent rise in sea levels allowed many new species to thrive in water. The Devonian spanned from 419–359 million years ago. Also known as "The Age of

380-458: A length of approximately 32 miles (50 km). The width of the range varies from 3–6 miles (5–10 km). The highest point on the range, Timber Mountain (7,565 feet), has a topographic prominence of approximately 3,400 feet. The types, sizes, and profiles of the Caballo watersheds vary significantly according to the part of the range that they drain. No perennial streams flow through

475-402: A more unified bureau mission and recognized the value of the remaining public lands by declaring that these lands would remain in public ownership. The law directed that these lands be managed with a view toward "multiple use" defined as "management of the public lands and their various resource values so that they are utilized in the combination that will best meet the present and future needs of

570-614: A pilot project on the Pryor Mountains Wild Horse Range known as the Adopt-A-Horse initiative. The program took advantage of provisions in the WFRHBA to allow private "qualified" individuals to "adopt" as many horses as they wanted if they could show that they could provide adequate care for the animals. At the time, title to the horses remained permanently with the federal government. The pilot project

665-513: A regular and recurring presence on a vast amount of public lands, roads and recreation sites. They focus on the protection of natural and cultural resources, other BLM employees and visitors. Given the many locations of BLM public lands, these rangers use canines, helicopters, snowmobiles, dirt bikes and boats to perform their duties. By contrast BLM special agents are criminal investigators who plan and conduct investigations concerning possible violations of criminal and administrative provisions of

760-534: A third stage beginning in the late Miocene or early Pliocene and continuing to the recent past. Activity in the vicinity of the Caballos during the first stage included explosive rhyolitic eruptions from cauldrons located to the northwest, west, and southeast. The earliest eruptions took place in the Dona Ana Mountains and Organ Mountains between 36.2 and 35.4 Ma. The Emory cauldron, located in

855-1652: Is a critical factor for both plants and animals. Soils on the mountains are generally rocky and thin. Plant communities can be generally characterized as Chihuahuan desert scrublands, creosotebush desert, and desert grasslands. Dominant shrub species include creosote bush ( Larrea tridentata ), honey mesquite ( Prosopis glandulosa ), soaptree yucca ( Yucca elata ), and four winged saltbush ( Atriplex canescens ). Common grasses include black grama ( Bouteloua eriopoda ), blue grama ( Bouteloua gracilis ), sideoats grama ( Bouteloua curtipendula ), and alkali sacaton ( Sporobolus airoides ). The most common mammalian predators are mountain lions ( Felis concolor ) and coyotes ( Canis latrans ). Other common mammals are Black-tailed jackrabbit ( Lepus californicus ), desert cottontail , ( Sylvilagus auduboni ) and kangaroo rats ( Dipodomys merriami and Dipodomys spectabilis ). Common birds of prey include golden eagles ( Aquila chrysaetos ), Swainson's hawk ( Buteo swainsoni ), Northern harrier ( Circus cyaneus ), and burrowing owl ( Athene cunicularia ). Other birds include roadrunner ( Geococcyx californianus ), quail ( Callipepla gambelii and Callipepla squamata ), doves ( Zenaida macroura and Zenaida asiatica ). Common reptiles include Collared lizards ( Crotaphytus collaris ), Roundtail Horned Lizard ( Phrynosoma modestum ), Striped whipsnake ( Masticophis taeniatus ), and Western diamondback rattlesnake ( Crotalus atrox ). Bureau of Land Management The Bureau of Land Management ( BLM )

950-720: Is an agency within the United States Department of the Interior responsible for administering U.S. federal lands . Headquartered in Washington, D.C. , the BLM oversees more than 247.3 million acres (1,001,000 km ) of land, or one-eighth of the United States's total landmass. The Bureau was created by Congress during the presidency of Harry S. Truman in 1946 by combining two existing agencies:

1045-663: Is considered the first Phanerozoic mass extinction event, and the second deadliest. The Silurian spanned from 444–419 million years ago. The Silurian saw the rejuvenation of life as the Earth recovered from the previous glaciation. This period saw the mass evolution of fish, as jawless fish became more numerous, jawed fish evolved, and the first freshwater fish evolved, though arthropods, such as sea scorpions , were still apex predators . Fully terrestrial life evolved, including early arachnids, fungi, and centipedes. The evolution of vascular plants ( Cooksonia ) allowed plants to gain

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1140-409: Is expanded in the fourth timeline, and the most recent epoch is expanded in the fifth timeline. Horizontal scale is Millions of years (above timelines) / Thousands of years (below timeline) The history of movement along the rift has been divided into three separate stages: an initial stage during the late Eocene to early Oligocene , a second stage during the late Oligocene to late Miocene , and

1235-403: Is found over the course of the rift. The following five timelines show the geologic time scale to scale. The first shows the entire time from the formation of the Earth to the present, but this gives little space for the most recent eon. The second timeline shows an expanded view of the most recent eon. In a similar way, the most recent era is expanded in the third timeline, the most recent period

1330-887: Is greater than that of all earlier Paleozoic rocks. Above the Magdalena Group is the Red House Formation of packstone and shale, the Nakaye Formation of limestone, the Bar B Formation of interbedded limestone, dolomite, shale, and conglomerate , and the red shale beds of the Abo Formation . All of those strata are Pennsylvanian in age. Above them is the Permian Yeso Formation , which consists of sandstones, siltstone-dolomites, and limestones. The Paleozoic strata are completed by

1425-553: Is not protected by a national park or monument designation. The BLM's May 30, 2019 statement proposed an additional 183,668 acres on "lands managed by the Canyon Country, Color Country, Green River, and West Desert districts" that would be listed for the quarterly oil and gas lease sale on September 10, 2019. In their May 2019, September lease offerings, the BLM said that they had "245 million acres of public land located primarily in 12 Western states, including Alaska" and across

1520-637: Is the SIG Sauer P320 chambered in 9mm which is replacing the SIG Sauer P226 /P229 both chambered in .40 S&W. The BLM manages free-roaming horses and burros on public lands in ten western states. Though they are feral , the agency is obligated to protect them under the Wild and Free-Roaming Horses and Burros Act of 1971 (WFRHBA). As the horses have few natural predators, populations have grown substantially. WFRHBA as enacted provides for

1615-540: Is the agency's largest ever purchase in the state. In 2024 the Department of the Interior has begun to advance a new rule according to which the Bureau of Land Management can distribute restoration leases and mitigation leases exactly in the same way as it distributes new leases for oil and gas drilling. The designed land will be used for nature conservation including use of indigenous knowledge. Established in 2000,

1710-511: Is the case with many other mountain ranges in southern New Mexico, the Caballo Mountains impose extreme demands on ecological communities. With the exception of the intermittent streams in the northern part of the range, and the area in close proximity to the Rio Grande, there is very little permanent water. Precipitation quickly evaporates, runs off, or soaks into the ground, leaving little for plants or animals. Consequently, water management

1805-575: Is the sudden appearance of nearly all of the invertebrate animal phyla in great abundance at the beginning of the Cambrian. The first vertebrates appeared in the form of primitive fish, which greatly diversified in the Silurian and Devonian Periods. The first animals to venture onto dry land were the arthropods. Some fish had lungs, and powerful bony fins that in the late Devonian, 367.5 million years ago, allowed them to crawl onto land. The bones in their fins eventually evolved into legs and they became

1900-605: The Appalachians , Caledonides , Ural Mountains , and mountains of Tasmania . The Cambrian spanned from 539–485 million years ago and is the first period of the Paleozoic Era of the Phanerozoic. The Cambrian marked a boom in evolution in an event known as the Cambrian explosion in which the largest number of creatures evolved in any single period of the history of the Earth. Creatures like algae evolved, but

1995-754: The Black Range , was active approximately 34.9 Ma. What is now the San Mateo Mountains (Socorro County) contained at least two cauldrons, the Nogal Canyon cauldron (28.6 Ma) and the Mount Withington cauldron (27.4 Ma). Local subsiding appears to have begun around 34.9 Ma. The Caballo Mountains began to rise in the late Oligocene, and throughout the Miocene. Approximately 9.6 Ma, the eruption of basalts near Fort Selden signaled

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2090-531: The Carboniferous Rainforest Collapse . Gondwana was glaciated as much of it was situated around the south pole. The Permian spanned from 299–252 million years ago and was the last period of the Paleozoic Era. At the beginning of this period, all continents joined together to form the supercontinent Pangaea, which was encircled by one ocean called Panthalassa . The land mass was very dry during this time, with harsh seasons, as

2185-472: The Department of the Interior . It took several years for this new agency to integrate and reorganize. In the end, the Bureau of Land Management became less focused on land disposal and more focused on the long term management and preservation of the land. The agency achieved its current form by combining offices in the western states and creating a corresponding office for lands both east of and alongside

2280-645: The Early Palaeozoic Icehouse , culminating in the Hirnantian glaciation, 445  million years ago at the end of the Ordovician. The middle Paleozoic was a time of considerable stability. Sea levels had dropped coincident with the ice age, but slowly recovered over the course of the Silurian and Devonian. The slow merger of Baltica and Laurentia, and the northward movement of bits and pieces of Gondwana created numerous new regions of relatively warm, shallow sea floor. As plants took hold on

2375-708: The Grand Staircase–Escalante National Monument in southern Utah, the first of now 20 national monuments established on BLM lands and managed by the agency. The establishment of Grand Staircase–Escalante foreshadowed later creation of the BLM's National Landscape Conservation System in 2000. Use of the Antiquities Act authority, to the extent it effectively scuttled a coal mine to have been operated by Andalex Resources , delighted recreation and conservation enthusiasts but set up larger confrontations with state and local authorities. Under

2470-786: The Meseta Blanca Sandstone Member . Most of the Mesozoic rocks are missing from the Caballo geological history. A second unconformity lies above the Meseta Blanca Sandstone, and includes all of the Triassic and Jurassic periods. The next oldest rocks are of Cretaceous age and include: The Mesozoic rocks terminate below another unconformity. Above that is the Love Ranch Formation of conglomerate, mudstone and sandstone, which

2565-702: The Mississippi River . As a matter of course, the BLM's emphasis fell on activities in the western states as most of the mining, land sales, and federally owned areas are located west of the Mississippi. BLM personnel on the ground have typically been oriented toward local interests, while bureau management in Washington are led by presidential guidance. By means of the Federal Land Policy and Management Act of 1976, Congress created

2660-735: The National Conservation Lands (formerly known as the National Landscape Conservation System), totaling about 36 million acres (150,000 km ). In addition the National Conservation Lands include nearly 2,400 miles of Wild and Scenic Rivers , and nearly 6,000 miles of National Scenic and Historic Trails . There are more than 63,000 oil and gas wells on BLM public lands. Total energy leases generated approximately $ 5.4 billion in 2013, an amount divided among

2755-603: The National Landscape Conservation System is overseen by the BLM. The National Landscape Conservation System lands constitute just about 12% of the lands managed by the BLM. Congress passed Title II of the Omnibus Public Land Management Act of 2009 (Public Law 111-11) to make the system a permanent part of the public lands protection system in the United States. By designating these areas for conservation,

2850-712: The Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma at the start of the Mesozoic Era. The Paleozoic is subdivided into six geologic periods (from oldest to youngest), Cambrian , Ordovician , Silurian , Devonian , Carboniferous and Permian . Some geological timescales divide the Paleozoic informally into early and late sub-eras: the Early Paleozoic consisting of

2945-551: The Selden basalts, and the Camp Rice / Palomas Formations (ash fall deposits, basalts, and pumice -clast conglomerates). Quaternary and Holocene deposits consist of alluvium . On the west side of the range along the Rio Grande, the alluvial fill consists of unconsolidated fluvial deposits of boulders, cobble , and gravel. In the closed basin on the east side of the range, there are relatively few fluvial deposits. Instead,

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3040-571: The South Pole . The early Paleozoic climate was strongly zonal, with the result that the "climate", in an abstract sense, became warmer, but the living space of most organisms of the time – the continental shelf marine environment – became steadily colder. However, Baltica (Northern Europe and Russia) and Laurentia (eastern North America and Greenland) remained in the tropical zone, while China and Australia lay in waters which were at least temperate. The early Paleozoic ended, rather abruptly, with

3135-682: The Treasury , the states, and Native American groups. The BLM's roots go back to the Land Ordinance of 1785 and the Northwest Ordinance of 1787. These laws provided for the survey and settlement of the lands that the original Thirteen Colonies ceded to the federal government after the American Revolution . As additional lands were acquired by the United States from Spain , France and other countries,

3230-703: The United States Congress directed that they be explored, surveyed, and made available for settlement. During the Revolutionary War, military bounty land was promised to soldiers who fought for the colonies. After the war, the Treaty of Paris of 1783 , signed by the United States, the UK , France , and Spain , ceded territory to the United States. In the 1780s, other states relinquished their own claims to land in modern-day Ohio . By this time,

3325-742: The United States General Land Office and the Grazing Service . The agency manages the federal government's nearly 700 million acres (2,800,000 km ) of subsurface mineral estate located beneath federal, state and private lands severed from their surface rights by the Homestead Act of 1862 . Most BLM public lands are located in these 12 western states: Alaska , Arizona , California , Colorado , Idaho , Montana , Nevada , New Mexico , Oregon , Utah , Washington and Wyoming . The mission of

3420-641: The United States General Land Office as part of the Department of the Treasury to oversee the disposition of these federal lands. By the early 1800s, promised bounty land claims were finally fulfilled. In the 19th century, other bounty land and homestead laws were enacted to dispose of federal land. Several different types of patents existed. These include cash entry, credit, homestead, Indian, military warrants, mineral certificates, private land claims, railroads, state selections, swamps, town sites, and town lots. A system of local land offices spread throughout

3515-571: The American people." Since the Reagan administration in the 1980s, Republicans have often given priority to local control and to grazing, mining and petroleum production, while Democrats have more often emphasized environmental concerns even when granting mining and drilling leases. In September 1996, then President Bill Clinton used his authority under the Antiquities Act to establish

3610-503: The BLM and other statutes under the United States Code. Special agents are normally plain clothes officers who carry concealed firearms and other defensive equipment, make arrests, carry out complex criminal investigations, present cases for prosecution to local United States Attorneys and prepare investigative reports. Criminal investigators occasionally conduct internal and civil claim investigations. The current sidearm

3705-513: The BLM is "to sustain the health, diversity, and productivity of the public lands for the use and enjoyment of present and future generations." Originally BLM holdings were described as "land nobody wanted" because homesteaders had passed them by. All the same, ranchers hold nearly 18,000 permits and leases for livestock grazing on 155 million acres (630,000 km ) of BLM public lands. The agency manages 221 wilderness areas , 29 national monuments and some 636 other protected areas as part of

3800-633: The Biden administration, the BLM is working on a pilot project called "outcomes-based grazing", to see if cattle grazing can help achieve conservation, agency director Tracy Stone-Manning said in an interview published in April 2022. In June 2022, the BLM finalized two acquisitions in Colorado and Wyoming, acquiring over 40,000 acres of previously inaccessible land. The acquisition in Wyoming for 35,670 acres

3895-507: The Caballos include plutons of granite , and metamorphic amphibolite and gneiss . These rocks date from the Early to Middle Proterozoic , and are found along the base of the larger fault blocks. Throughout the early and middle Paleozoic southern New Mexico alternated between being flooded by shallow tropical seas, and being exposed to erosion. Sedimentary deposits of early and middle Paleozoic age include: An unconformity exists above

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3990-633: The Cambrian, Ordovician and Silurian; the Late Paleozoic consisting of the Devonian, Carboniferous and Permian. The name Paleozoic was first used by Adam Sedgwick (1785–1873) in 1838 to describe the Cambrian and Ordovician periods. It was redefined by John Phillips (1800–1874) in 1840 to cover the Cambrian to Permian periods. It is derived from the Greek palaiós (παλαιός, "old") and zōḗ (ζωή, "life") meaning "ancient life". The Paleozoic

4085-592: The Fish", the Devonian featured a huge diversification of fish, including armored fish like Dunkleosteus and lobe-finned fish which eventually evolved into the first tetrapods. On land, plant groups diversified rapidly in an event known as the Devonian explosion when plants made lignin , leading to taller growth and vascular tissue; the first trees and seeds evolved. These new habitats led to greater arthropod diversification. The first amphibians appeared and fish occupied

4180-733: The Lake Valley Formation, and appears to include the middle Mississippian through the early Pennsylvanian periods. During the Pennsylvanian and Permian periods, a major deformation created a series of uplifts and intermontane basins. This event is often referred to as the Ancestral Rocky Mountains. Associated with this event is the Magdalena Group , which includes deposits of both marine and non-marine sources. The thickness of these strata

4275-601: The Mesozoic Era to recover. Recovery of life in the sea may have been much faster. The base of the Paleozoic is one of the major divisions in geological time representing the divide between the Proterozoic and Phanerozoic eons, the Paleozoic and Neoproterozoic eras and the Ediacaran and Cambrian periods. When Adam Sedgwick named the Paleozoic in 1835, he defined the base as the first appearance of complex life in

4370-404: The Middle Carboniferous). An important evolutionary development of the time was the evolution of amniotic eggs , which allowed amphibians to move farther inland and remain the dominant vertebrates for the duration of this period. Also, the first reptiles and synapsids evolved in the swamps. Throughout the Carboniferous, there was a cooling trend, which led to the Permo-Carboniferous glaciation or

4465-454: The National Parks and Public Land Legacy Restoration Fund each year for five years for needed maintenance for critical facilities and infrastructure in national parks, forests, wildlife refuges, recreation areas and American Indian schools. The Act also committed $ 900 million a year in royalties from offshore oil and natural gas to permanently fund the Land and Water Conservation Fund investments in conservation and recreation opportunities across

4560-514: The Palaeozoic had very few facultatively motile animals that could easily adjust to disturbance, with such creatures composing 1% of its assemblages in contrast to 50% in Cenozoic faunal assemblages. Non-motile animals untethered to the substrate, extremely rare in the Cenozoic, were abundant in the Palaeozoic. Palaeozoic phytoplankton overall were both nutrient-poor themselves and adapted to nutrient-poor environmental conditions. This phytoplankton nutrient poverty has been cited as an explanation for

4655-404: The Paleozoic and Mesozoic eras and the Permian and Triassic periods is marked by the first occurrence of the conodont Hindeodus parvus . This is the first biostratigraphic event found worldwide that is associated with the beginning of the recovery following the end- Permian mass extinctions and environmental changes. In non-marine strata, the equivalent level is marked by the disappearance of

4750-462: The Permian Dicynodon tetrapods . This means events previously considered to mark the Permian-Triassic boundary, such as the eruption of the Siberian Traps flood basalts , the onset of greenhouse climate, ocean anoxia and acidification and the resulting mass extinction are now regarded as being of latest Permian in age. The GSSP is near Meishan , Zhejiang Province, southern China. Radiometric dating of volcanic clay layers just above and below

4845-464: The Silurian Period, about 420 million years ago, when they began to transition onto dry land. Terrestrial flora reached its climax in the Carboniferous, when towering lycopsid rainforests dominated the tropical belt of Euramerica . Climate change caused the Carboniferous Rainforest Collapse which fragmented this habitat, diminishing the diversity of plant life in the late Carboniferous and Permian periods. A noteworthy feature of Paleozoic life

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4940-497: The Trump administration, the BLM offered millions of acres of available Federal lands for 10-year leases for commercial development, potentially in oil and gas and mining, with the stated goal of "promoting American energy security". The BLM holds quarterly oil and gas lease sales. According to a June 18, 2018 article in The Atlantic , under the tenure of then- United States Secretary of the Interior , Ryan Zinke "practically gave away hundreds of thousands of acres of open land across

5035-481: The United States another "700 million acres of sub-surface mineral estate" is under their management. The statement also said that these "diverse activities authorized on these lands generated $ 96 billion in sales of goods and services throughout the American economy in fiscal year 2017" while supporting over 468,000 jobs". On August 4, 2020, President Trump signed the Great American Outdoors Act into law, committing up to $ 1.9 billion from energy development revenues to

5130-475: The United States needed revenue to function and land was sold as a source of income for the government. In order to sell the land, surveys needed to be conducted. The Land Ordinance of 1785 instructed a geographer to oversee this work as undertaken by a group of surveyors. The first years of surveying were completed by trial and error; once the territory of Ohio had been surveyed, a modern public land survey system had been developed. In 1812, Congress established

5225-722: The United States. There are several herds of horses and burros roaming free on 26.9 million acres of range spread out in ten western states. It is essential to maintain a balance that keeps herd management land and animal population healthy. Some programs and partnerships include the Mustang Heritage Foundation, U.S. Border Patrol, Idaho 4H, Napa Mustang Days and Little Book Cliffs Darting Team. These partnerships help with adoption and animal population as well as education and raising awareness about wild horses and burros. In 2009, BLM opened Renewable Energy Coordination Offices in order to approve and oversee wind, solar, biomass, and geothermal projects on BLM-managed lands. The offices were located in

5320-492: The West, leasing it to energy companies for pennies on the dollar." The Salt Lake Tribune reported that in March 2019, the price per acre for leases near the Golden Spike National Historical Park , in Utah were "$ 1.50 an acre for the next two years". By September 11, 2018, the Department of Interior was offering 2.9 million acres to be leased to commercial operations including drilling for oil and gas and mining in New Mexico, Colorado, Arizona, and other states where public land

5415-434: The basal Cambrian Global Stratotype Section and Point (GSSP) at the base of the Treptichnus pedum assemblage of trace fossils and immediately above the last occurrence of the Ediacaran problematica fossils Harlaniella podolica and Palaeopsacichnus . The base of the Phanerozoic, Paleozoic and Cambrian is dated at 538.8+/-0.2 Ma and now lies below both the first appearance of trilobites and SSF. The boundary between

5510-454: The boundary confine its age to a narrow range of 251.902+/-0.024 Ma. The beginning of the Paleozoic Era witnessed the breakup of the supercontinent of Pannotia and ended while the supercontinent Pangaea was assembling. The breakup of Pannotia began with the opening of the Iapetus Ocean and other Cambrian seas and coincided with a dramatic rise in sea level. Paleoclimatic studies and evidence of glaciers indicate that Central Africa

5605-511: The climate of the interior of Pangaea was not regulated by large bodies of water. Diapsids and synapsids flourished in the new dry climate. Creatures such as Dimetrodon and Edaphosaurus ruled the new continent. The first conifers evolved, and dominated the terrestrial landscape. Near the end of the Permian, however, Pangaea grew drier. The interior was desert, and new taxa such as Scutosaurus and Gorgonopsids filled it. Eventually they disappeared, along with 95% of all life on Earth, in

5700-561: The continental margins, oxygen levels increased and carbon dioxide dropped, although much less dramatically. The north–south temperature gradient also seems to have moderated, or metazoan life simply became hardier, or both. At any event, the far southern continental margins of Antarctica and West Gondwana became increasingly less barren. The Devonian ended with a series of turnover pulses which killed off much of middle Paleozoic vertebrate life, without noticeably reducing species diversity overall. There are many unanswered questions about

5795-401: The country. Also in August 2020, the BLM headquarters was relocated to Grand Junction, Colorado , by an order signed by Interior Secretary David Bernhardt . The relocation was praised by Republican Western politicians but criticized by Democrats as a move to weaken the agency through the loss of experienced staffers, who opted to stay in Washington, D.C. Some ranchers were concerned about

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5890-508: The early successes of the adoption program, the BLM has struggled to maintain acceptable herd levels, as without natural predators, herd sizes can double every four years. As of 2014, there were more than 49,000 horses and burros on BLM-managed land, exceeding the BLM's estimated "appropriate management level" (AML) by almost 22,500. The Bureau of Land Management has implemented several programs and has developed partnerships as part of their management plan for preserving wild burros and horses in

5985-430: The east side is drained by Jornada Draw. This drainage, however, is endorheic and has no surface connection to the Rio Grande. The geological importance of the Caballo Mountains lies in the variety and scope of their exposed rocks. Geologists can assess exposed rock formations in several ways. Relative dating compares the formation's bedding location in comparison with other formations nearby. This allows not only

6080-432: The eastern side has only two primary drainages, each with a much lower gradient than those to the north and west. Water falling on the southern half of the east side flows into Barbee Draw. After joining another tributary near Point of Rocks to form Rincon Arroyo, this ephemeral drainage flows southward before joining the Rio Grande near Rincon, New Mexico . The length of this drainage is over 25 miles. The north portion of

6175-446: The empty continent of Gondwana. By the end of the Ordovician, Gondwana was at the south pole, early North America had collided with Europe, closing the intervening ocean. Glaciation of Africa resulted in a major drop in sea level, killing off all life that had established along coastal Gondwana. Glaciation may have caused the Ordovician–Silurian extinction events , in which 60% of marine invertebrates and 25% of families became extinct, and

6270-560: The end of the Permian period. In late middle Permian the pareiasaurs originated, successful herbivores and the only sauropsids that could reach sizes comparable to some of the largest synapsids. The Palaeozoic marine fauna was notably lacking in predators relative to the present day. Predators made up about 4% of the fauna in Palaeozoic assemblages while making up 17% of temperate Cenozoic assemblages and 31% of tropical ones. Infaunal animals made up 4% of soft substrate Palaeozoic communities but about 47% of Cenozoic communities. Additionally,

6365-400: The first decade of the 20th century. Production has been concentrated in three areas: It has been estimated that the total value of copper, silver, gold, and lead produced from the Caballos before 1952 did not exceed $ 200,000. At present, more fluorspar is produced than any other mineral. The largest fluorspar deposits are found in Precambrian granite, and jasperized Fusselman Dolomite. As

6460-461: The first tetrapods, 390  million years ago , and began to develop lungs. Amphibians were the dominant tetrapods until the mid-Carboniferous, when climate change greatly reduced their diversity, allowing amniotes to take over. Amniotes would split into two clades shortly after their origin in the Carboniferous; the synapsids, which was the dominant group, and the sauropsids . The synapsids continued to prosper and increase in number and variety till

6555-470: The four states where energy companies had shown the greatest interest in renewable energy development: Arizona , California , Nevada , and Wyoming . Paleozoic The Paleozoic ( / ˌ p æ l i . ə ˈ z oʊ . ɪ k , - i . oʊ -, ˌ p eɪ -/ PAL-ee-ə-ZOH-ik , -⁠ee-oh- , PAY- ; or Palaeozoic ) Era is the first of three geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds

6650-449: The identification of the older and younger formations, but conclusions about unusual local conditions, such as folding , a fault displacement, or an unconformity . Absolute dating measures the presence and ratios of chemicals within the rocks to determine the number of years since they were deposited. The conditions existing when the rock was deposited can be determined by examining its type ( igneous , metamorphic , or sedimentary ),

6745-440: The isolation of Grand Junction compared to other Western cities, having limited flights and road access. After the announcement, 87% of D.C.-based employees left, prompting former lead career BLM official Steve Ellis to state "the bureau lost a tremendous amount of expertise...[of] very seasoned people." On September 17, 2021, Secretary Deb Haaland announced that the headquarters would be moved back to Washington, D.C. Under

6840-651: The late Paleozoic, great forests of primitive plants covered the continents, many of which formed the coal beds of Europe and eastern North America . Towards the end of the era, large, sophisticated synapsids and diapsids were dominant and the first modern plants ( conifers ) appeared. The Paleozoic Era ended with the largest extinction event of the Phanerozoic Eon , the Permian–Triassic extinction event . The effects of this catastrophe were so devastating that it took life on land 30 million years into

6935-611: The late Paleozoic. The Mississippian (early Carboniferous Period) began with a spike in atmospheric oxygen, while carbon dioxide plummeted to new lows. This destabilized the climate and led to one, and perhaps two, ice ages during the Carboniferous. These were far more severe than the brief Late Ordovician ice age; but, this time, the effects on world biota were inconsequential. By the Cisuralian Epoch, both oxygen and carbon dioxide had recovered to more normal levels. On

7030-869: The law directed the BLM to ensure these places are protected for future generations, similar to national parks and wildlife refuges . Source: BLM Resources and Statistics The BLM, through its Office of Law Enforcement & Security, functions as a federal law enforcement agency of the United States Government. BLM law enforcement rangers and special agents receive their training through Federal Law Enforcement Training Centers (FLETC). Full-time staffing for these positions approaches 300. Uniformed rangers enforce laws and regulations governing BLM lands and resources. As part of that mission, these BLM rangers carry firearms and defensive equipment, make arrests, execute search warrants, complete reports and testify in court. They seek to establish

7125-504: The majority of Ediacaran to Cambrian rock sequences are composed of siliciclastic rocks where skeletal fossils are rarely preserved. This led the International Commission on Stratigraphy (ICS) to use trace fossils as an indicator of complex life. Unlike later in the fossil record, Cambrian trace fossils are preserved in a wide range of sediments and environments, which aids correlation between different sites around

7220-603: The most ubiquitous of that period were the armored arthropods, like trilobites. Almost all marine phyla evolved in this period. During this time, the supercontinent Pannotia begins to break up, most of which later became the supercontinent Gondwana. The Ordovician spanned from 485–444 million years ago. The Ordovician was a time in Earth's history in which many of the biological classes still prevalent today evolved, such as primitive fish, cephalopods, and coral. The most common forms of life, however, were trilobites, snails and shellfish. The first arthropods went ashore to colonize

7315-528: The mountains, although the course of the Rio Grande is close to the north, west, and south margins of the range. The northern part of the Caballos drains into the Rio Grande through Ash Canyon and Mescal Canyon. The confluences of those two intermittent streams are just below Elephant Butte Dam . Water falling on the precipitous west face of the range drains directly into the Rio Grande by means of numerous first order canyons with high gradients . All are ephemeral and less than 3 miles in length. In contrast,

7410-595: The orientation and size of crystals or sediments within it, and the orientation of the formation within its larger regional setting. By studying plant and animal fossils that may exist in the formation, it may be possible to determine not only its relative age, but the climate at the time of deposition. Weathering and erosion remove any rock that is exposed at the surface of the Earth. Consequently, there are no sites where all rocks deposited at that location have been preserved. Certain sites, however, may have more complete geological histories because of differences in

7505-575: The other hand, the assembly of Pangaea created huge arid inland areas subject to temperature extremes. The Lopingian Epoch is associated with falling sea levels, increased carbon dioxide and general climatic deterioration, culminating in the devastation of the Permian extinction. While macroscopic plant life appeared early in the Paleozoic Era and possibly late in the Neoproterozoic Era of the earlier eon, plants mostly remained aquatic until

7600-467: The public rangelands by establishment of advisory boards that set grazing fees. The Oregon and California Revested Lands Sustained Yield Management Act of 1937, commonly referred as the O&;C Act, required sustained yield management of the timberlands in western Oregon. In 1946, the Grazing Service was merged with the United States General Land Office to form the Bureau of Land Management within

7695-610: The removal of excess animals; the killing of lame, old, or sick animals; the private placement or adoption of excess animals; and even the killing of healthy animals if range management required it. The killing of healthy or unhealthy horses has almost never occurred. Pursuant to the Public Rangelands Improvement Act of 1978 , the BLM has established 179 "herd management areas" (HMAs) covering 31.6 million acres (128,000 km ) acres where feral horses can be found on federal lands. In 1973, BLM began

7790-414: The renewal of crustal extension and volcanism in the southern part of the rift. Activity along both older and new faults increased the number, but decreased the width of basins along this portion of the rift. The Caballo Mountains have few large intrusives, and as a result, hydrothermal mineralization is not extensive. Nevertheless, prospecting in the range began in about 1883, and several mines opened in

7885-401: The rock record as shown by the presence of trilobite -dominated fauna. Since then evidence of complex life in older rock sequences has increased and by the second half of the 20th century, the first appearance of small shelly fauna (SSF), also known as early skeletal fossils, were considered markers for the base of the Paleozoic. However, whilst SSF are well preserved in carbonate sediments,

7980-648: The sediment includes a flat, thin veneer of sand and gravel. The Rio Grande Rift is a continental rift zone, which extends approximately 680 miles (~1,100 km) from central Colorado in the north to the state of Chihuahua , Mexico in the south. It is the product of extensional tectonic (or divergent) forces that formed a series of basins between the Colorado Plateau and the North American craton Thin continental crust , normal fault block topography, high regional elevation, and volcanism

8075-479: The short, but apparently severe, late Ordovician ice age. This cold spell caused the second-greatest mass extinction of the Phanerozoic Eon. Over time, the warmer weather moved into the Paleozoic Era. The Ordovician and Silurian were warm greenhouse periods, with the highest sea levels of the Paleozoic (200 m above today's); the warm climate was interrupted only by a 30 million year cool period,

8170-795: The southern part of the Caballo Mountains, there are remnants of a region wide sheet of flood basalts and andesite, which was laid during the Oligocene . Of similar age is the Thurman Formation of white sandstone. The Santa Fe Group (geology) was deposited during the Miocene and Pliocene . This thick layer consists of the Hayner Ranch Formation (conglomerate, sandstone and shale), the Rincon Valley Formation (conglomerate, sandstone, and mudstone),

8265-638: The territories, patenting land that was surveyed via the corresponding Office of the Surveyor General of a particular territory. This pattern gradually spread across the entire United States. The laws that spurred this system with the exception of the General Mining Law of 1872 and the Desert Land Act of 1877 have since been repealed or superseded. In the early 20th century, Congress took additional steps toward recognizing

8360-523: The timing and circumstances of rock removal. The Caballo Mountains are essentially unique in New Mexico because their section of exposed rocks begins in Precambrian time, and runs through every geological period of the Phanerozoic eon with the exceptions of the Triassic and Jurassic . This provides an unparalleled picture of the geological history of southern New Mexico. The basement rocks of

8455-554: The top of the food chain. Earth's second Phanerozoic mass extinction event (a group of several smaller extinction events), the Late Devonian extinction , ended 70% of existing species. The Carboniferous is named after the large coal deposits laid down during the period. It spanned from 359–299 million years ago. During this time, average global temperatures were exceedingly high; the early Carboniferous averaged at about 20 degrees Celsius (but cooled to 10 °C during

8550-548: The value of the assets on public lands and directed the Executive Branch to manage activities on the remaining public lands. The Mineral Leasing Act of 1920 allowed leasing, exploration, and production of selected commodities, such as coal , oil , gas , and sodium to take place on public lands. The Taylor Grazing Act of 1934 established the United States Grazing Service to manage

8645-521: The world. Trace fossils reflect the complexity of the body plan of the organism that made them. Ediacaran trace fossils are simple, sub-horizontal feeding traces. As more complex organisms evolved, their more complex behaviour was reflected in greater diversity and complexity of the trace fossils they left behind. After two decades of deliberation, the ICS chose Fortune Head , Burin Peninsula, Newfoundland as

8740-426: Was a time of dramatic geological, climatic, and evolutionary change. The Cambrian witnessed the most rapid and widespread diversification of life in Earth's history, known as the Cambrian explosion , in which most modern phyla first appeared. Arthropods , molluscs , fish , amphibians , reptiles , and synapsids all evolved during the Paleozoic. Life began in the ocean but eventually transitioned onto land, and by

8835-649: Was deposited in the Paleocene to early Eocene . During the Eocene , a wave of arc volcanism was felt across southern New Mexico. In the Caballo Mountains, this can be seen in the Palm Park Formation , a thick layer of andesitic or tuffaceous mudstones, sandstones, and breccia . Next is the Bell Top Formation , which consists of rhyolite , basalt flows, and tuffaceous sandstones. In

8930-539: Was most likely in the polar regions during the early Paleozoic. The breakup of Pannotia was followed by the assembly of the huge continent Gondwana ( 510  million years ago ). By the mid-Paleozoic, the collision of North America and Europe produced the Acadian-Caledonian uplifts, and a subducting plate uplifted eastern Australia . By the late Paleozoic, continental collisions formed the supercontinent of Pangaea and created great mountain chains, including

9025-457: Was so successful that BLM allowed it to go nationwide in 1976. The Adopt-a-Horse program quickly became the primary method of removing excess feral horses from BLM land given the lack of other viable methods. The BLM also uses limited amounts of contraceptives in the herd, in the form of PZP vaccinations; advocates say that additional use of these vaccines would help to diminish the excess number of horses currently under BLM management. Despite

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