Rising over 3280 ft (1000 m) above the surrounding basins, the Franklin Mountains dominate the skyline of the city of El Paso. The range begins within the El Paso City limits in the south and extends northward across the New Mexico border for a distance of about 15 mi (24 km). The Franklins are the southernmost extension of an almost continuous series of north-south trending ranges that extend over 99 mi (160 km). The ranges include, from north to south: the San Andres, San Augustine, Organ, North Franklin, and Franklin ranges.
The continuous north-south ridge line of the Franklin and North Franklin mountains is separated by Anthony Gap approximately 0.5 mi (0.8 km) north of the New Mexico state line and the north park boundary. The 7 mi (11 km) long North Franklin Mountains are separated from the Organ Mountains by the 4.5 mi (7.2 km) Fillmore Pass (4210 ft, 1284 m). The ancestral Rio Grande flowed, prior to the erosional event that led to the stream piracy that has formed the current channel of the Rio Grande at Paso del Norte (Pass of the North) on the southwestern flank of the Franklin Mountains. The highest Peak in the North Franklins is North Anthony's Nose (5388 ft, 1643 m).
The major Franklin peaks, north to south, are: Anthony's Nose, North Mount Franklin, South Mount Franklin, Mount Franklin, and at the southern end of the Mount Franklin ridge Ranger and Comanche peaks. The major canyons of the range from north to south are Hitt, Fusselman, and McKelligon on the eastern side and Vinton, Avispa, and Fusselman on the western side. All of these canyons drain either east or west with the exception McKelligon that drains south-southeast out of the southeastern part of the range. The lowest elevation within park boundaries is approximately 4150 ft (1265 m). The highest elevation recorded in the range and the park is at North Franklin Mountain 7192 ft (2193 m) which is also the highest structural point in Texas.
No permanent surface water exists in the Franklin Mountains. However,
a number of springs and seeps will flow for most, if not all, of the year.
The majority of the water, however, is discharged beneath the surface in
rock-filled stream channels. Significant springs in the park include East
Cottonwood, West Cottonwood, and Mundy. Several dams have been constructed
in canyons and arroyos but these do not retain permanent pools of water.
Terms appearing in boldface [first mention] are defined in the glossary. Figures depicting Franklin Mountains geology are also provided.
Regional geological research has long in and around the Franklin Mountains.
The following discussion of the geology of the Franklins is largely derived
from Kottlowski and LeMone (1969); Harbour (1960, 1972); McAnulty (1968);
City of El Paso (1970); LeMone and Lovejoy, 1976; LeMone, 1983; LeMone
and Simpson, 1983; LeMone, 1996a, and LeMone, 1996b. Numerous additional
references about the geological history of the Franklin Mountains can be
found in such regional publications as the West Texas Geological Society,
El Paso Geological Society, Permian Basin Section of the Society of Economic
Paleontologists and Mineralogists, and the New Mexico Geological Society.
The Franklin Mountains form a long (15 mi, 24 km); narrow (5 mi, 8 km) range tilted to the west, which forms a reasonably typical example of basin and range faulting and its resultant physiography. The Franklin's are bounded by major east and west boundary faults, which form the boundary for the Hueco Bolson to the east and southeast and the Mesilla Valley to the west and southwest. The Rio Grande flows southward through the river cut terraces of the western Mesilla Valley and swings eastward through El Paso del Norte [Pass of the North] on the southeastern margin of the Franklins. It continues its eastward flow from there to the Gulf of Mexico. The verdant green of the rich, agricultural floodplain bounding the margins of the Rio Grande forms a stark contrast with the earth-toned Chihuahuan desert landscape of the region.
The long and complex geologic history of the Franklin Mountains is recorded in a general manner by six major suites of rocks. They are, from older to younger: Proterozoic (1.17 - 1.26 Ga [billion years]); Tobosa basin - related sedimentary rocks (500 - 362 Ma [million years]); Orogrande basin - related sedimentary rocks (344 - 270 Ma), Tethyan - related sedimentary rocks (110 - 88 Ma), Middle Eocene igneous rocks; and Late Tertiary, Quaternary and Recent sediments (2.68 Ma - present). Significant tectonic events and/or temporal intervals separate each of these units.
The Franklin Mesoproterozoic Era exposures contain six formations of metasedimentary and metaigneous rocks with an aggregate total thickness on the order of 5295 ft (1614 m). These formations are associated with a metaigneous sequence (Red Bluff Complex) consisting of a minimum of at least seven separate intrusions. All of the Precambrian units have their stratotypes in the Franklins. The oldest (1.26 Ga) unit, based on the analysis of zircons, is the 1400 ft (335 m) thick Castner Marble. The type section in Fusselman Canyon is particularly well exposed as a massive xenolith floating in the granitic intrusions of the Red Bluff Complex. The sediments of the Castner were deposited as a marine offshore siliceous and carbonate muds. These sediments were lithified into alternating strata of limestones, siltstones, and shales which were later metamorphosed into marbles and hornfels. The base of the Castner contains the oldest recognizable life in the range as microbial, probably cyanobacterial, stromatolites (e.g., Conophyton, etc.). Overlying the marble is a basaltic, submarine lava flow called the Mundy Breccia.
Above the Mundy Breccia and Castner Marble is the siliciclastic Lanoria Formation (2600 ft, 793 m) which is composed largely of hornfels and quartzites metamorphosed from the original marine and transitional sands and silts. This formation has remarkably well preserved primary sedimentation structures. It is separable into six members, with members 3 and 4 developing the spectacular cliffs visible on the eastern side of the central Franklins north of Trans-Mountain Road. The capping stratigraphic unit is the approximately 1100 ft (335 m) thick Thunderbird Group consists of thin, apparently continental, conglomerates and sands at its base (Coranado Hills Conglomerate). This is topped by some overlying flows and minor clastics (Smuggler Gap Formation) and, finally culminates in thick extrusive metaignimbrites (welded tuffs from nuee ardentes [French for fiery clouds]). This uppermost unit of Precambrian explosive volcanism is called the Tom Mays Park Formation. This reddish colored formation forms the crest of the central range in the area of North Mount Franklin. The igneous rocks of the Thunderbird Group appear to be genetically related to the intrusive (Note: follow the link to see a schematic cross section of the Precambrian to the Thunderbird Group) rocks of the Red Bluff Complex, which record the youngest Precambrian dates of 1.17 Ga. The history of the Franklins for the next 670 Ma is not recognized in the rock record. The simplest explanation for this is that the Franklin Mountains was either exposed and eroding or it was an area of non-deposition
The profound nonconformable unconformity of the Precambrian with the overlying Paleozoic is clearly recognizable in all exposures in the Franklin Mountains. The overlying thick (8910 ft, 2717 m), primarily marine carbonate Paleozoic sequence is divisible into two distinct tectonic - depositional units: a lower Tobosa basin - related suite (Early Ordovician - Late Devonian, 500 - 362 Ma) and the upper post Osagean Orogrande basin suite (Middle Mississippian - Early Permian, 344 - 270 Ma). Stratotypes for ten formations are in the Franklins, nine of which are within the park boundaries, seven of these are concentrated in the Vinton Canyon area.
The primarily equatorial to tropical marine carbonates of the Tobosa basin - related rocks include five depositional sequences; they are, in ascending order: Bliss Sandstone - El Paso Group (Lower Ordovician), Montoya Group (Upper Ordovician), Fusselman Dolomite (Silurian), Canutillo Formation (Middle Devonian), and Percha Shale (upper Devonian). The basal Bliss Sandstone, primarily quartzites, consists of reworked ancient beach sands deposited in shallow, offshore waters. There were some islands formed by resistant Precambrian hills (Thunderbird Archipelago) in the invading seas at this time which are recorded in the lowest part of the El Paso Group in the central Franklins.
The carbonates of the El Paso Group contains seven of the ten recognized regional formations of the El Paso Group in a nearly continuous set of exposures along the east flank of the mountains. The exposed (centimeter-exposed) section along Scenic Drive on the southern end of the range is considered to be the classic study area for carbonate cyclostratigraphy. It is also noteworthy for the bioherms of McKelligon Canyon Formation which are well exposed in the southern Franklins. The top of the Group displays some ancient soils (paleosols) as well as an extensive karst development of caves and sinkholes. The karsting was developed in an equatorial climate over a period of 27 Ma. These karsts mirror those, which are developed in the equivalent Permian Basin petroleum-producing unit the Ellenburger. Petroleum geologists visit the Franklin's to see these features in their spectacular three dimensional expression recorded on outcrops that are analogous to those in the subsurface producing Ellenburger. The basal, mottled, cliff forming unit (Upham Formation) of the overlying three formations of the Montoya Group forms the majority of the crest of the range from Fusselman Canyon to its southern terminus at Scenic Drive.
The Montoya Group is separated from the overlying white, sugary Silurian Fusselman Dolomite [by a small 5 Ma unconformity reflecting some minor karsting. The top of the Fusselman, conversely, exhibits major karsting that reflects some 40 Ma of tropical climate exposure. As in the case of the El Paso Group this feature is also analogous to Fusselman production in the Permian Basin (e.g., Dollarhide Field). The Fusselman forms the ridge crest of the range north of Mundy Gap, which is immediately north of North Mount Franklin.
The Middle Devonian Canutillo Formation is separated disconformably from the overlying Upper Devonian Percha Shale. The Percha Shale, as its equivalent unit in the Permian Basin, is a major petroleum source rock. This incompetent formation, as well as the uppermost El Paso Group Florida Mountains Formation, acted as glide planes for the numerous major landslides observed throughout the range.
Collision tectonics which are documented in the Marathon tectonic belt along the southern border of the North American continent resulted in a reconfiguration of the tectonic elements of the region. It resulted in the final formation of the Permian Basin and the local formation of the Orogrande basin in this region. This tectonic activity initiated in the medial Mississippian in the Franklins and ceased regionally in the Sierra Diablos in the Lower Permian. The resulting marine, primarily carbonate, Orogrande basin sequence can be subdivided into four discrete, genetically related sediments; they include, in ascending order: Las Cruces, Rancheria, Helms formations (Middle - Upper Mississippian), Magdalena Group (Lower - Middle Pennsylvanian), Panther Seep Formation Upper Mississippian), and Hueco Group (Lower Permian).
The basal Orogrande basin sequence initiates with the Las Cruces Formation. It consists of deep basin, distal, carbonate turbidites which become more shallow and proximal in the overlying Rancheria Formation. The uppermost Helms Formation is primarily shales with minor carbonates in the upper part. A sporadically developed paleosol on the top of the unit documents the disconformable contact between the lower slope-forming Mississippian Helms and the overlying basal cliff-forming Pennsylvanian Magdalena Group.
The Magdalena is composed of primarily cliff-forming carbonates at its base that becomes increasing more slope forming and siliciclastic towards the top of the group. Cyclic sedimentation, excellent phylloid algae and chaetetid sponge mounds are observed. The disconformable contact between this group and the overlying, very poorly exposed, clastic and evaporitic Panther Seep Formation is clearly marked by a basal distinct chert pebble conglomerate. The contact between the Pennsylvanian and the Permian is easily visible in only two localities, one of which is the easily accessible anticlinal flexure on the west side of the State Park public access road north of Trans-mountain road.
The thick (2514 ft, 766m), primarily marine carbonates of the three formations of the Hueco Group represents one of the finest Lower Permian (Wolfcampian) sections exposed in the southwest. Rocks assigned to the Middle and Upper Permian are not recognized in the Franklin Mountains. This part of the Permian and the overlying Triassic, Jurassic, and most of the Lower Cretaceous (290 - 110 Ma) is another segment of the lost history of the Franklins. These were the times when the region is interpreted to have been a portion of the tectonically unified and later disintegrating Pangean supercontinent.
During the middle Cretaceous an arm of the tropical to subtropical Eurasian Tethyan geosyncline] extended into this area of the southwest where it is known as the Chihuahua trough. The essentially medial Cretaceous Tethyan - related sequence consists of 12 formations with a cumulative, conservative aggregated thickness of 4596 ft (1401 m). The sequence ranges in age from Albian to Turonian (110 - 90 Ma). The estimated thickness Albian is 4116 ft (1255 m). The presence of older Aptian age rocks is not currently verifiable. Eight of the 12 formations have been documented in at least 23 separate localities in the Franklin Mountains area.
The Franklin Mountains during this time interval of deposition were positioned on the southern margin of the stable North American Continent. As a result the range is much are less disturbed by the Laramide orogeny than the sediments to the south in the Chihuahua trough. The Cretaceous sedimentary rocks of the Sierra Juarez, immediately south of the Franklins represents an excellent example. The mountains consist of a series of three superimposed thrust plates driven into position from the southwest. This sequence documents a surface foreshortening of a minimum of 13.8 mi (22 km). This figure is obtained by unstacking the thrusts one after another and measuring the distance. An actually more realistic figure, but undocumented here, is probably on the order of 37.5 mi (60 km).
The timing of the Laramide orogeny, which in this region is documented with this thrusting event, must be no older than the Turonian (90 Ma) of the Cretaceous and no younger than the Middle Eocene (90 - 47.2 Ma). This is verified by the fact that the Turonian sediments in the Sierra Juarez are intruded by the Middle Eocene igneous rock. Intrusions in the Franklins are primarily restricted to the western side of the range. This intrusive event is also recorded at the immediately adjacent Mount Cristo Rey on the New Mexico - Mexico border as well as at the Three Sisters and the Campus Andesite on the southwest part of the range. A felsite sill noted in the Bliss - El Paso Group on the southeastern side of the range is probably related to the Middle Eocene intrusion, despite erroneously (argon loss) being radioactively dated as Upper Oligocene (28 Ma).
The Late Cenozoic basin and range faulting of the region probably initiated about Late Miocene (10 Ma). Age dating, utilizing the mineral Jarosite from a mine in the Webb Gap area in the North Franklins, records Pliocene movements at 3.8 Ma and 5.2 Ma (Leuth et al., 1998). The bounding faults of the range indicate a Hueco bolson drop of 9000 ft (2744 m) on the east side of the range and 10,000 ft (3049 m) along the western Mesilla Valley side. The west boundary fault zone places Permian rocks adjacent to Precambrian. This is easily observable on the public access road into the State Park. The road is paved in large part on the west boundary fault zone. As the park public picnicking is entered and crossing the first arroyo, the red Precambrian metamorphosed welded tuffs of the Tom Lea Park Formation can be seen on the right (eastern) side, while of the left (western) side the bedded carbonates of the Permian Hueco Canyon Formation are visible. The road is on the fault trace of the west boundary fault zone. Here it documents a western block downdrop on the order of 1.5 mi (2.4 km). This western downdrop represents the valley, while to the east is the range of what is an excellent example of what is referred to as the Basin and Range structural and physiographic province.
Pliocene - Pleistocene sediments of the valley are exposed in the downwardly eroded terraces on the western Mesilla Valley side of the range. These sediments range from youngest Late Blancan (2.68-2.02 Ma) to the Irvingtonian (2.02-1.02 Ma) based on mammalian faunas. This Mesilla Valley sequence of continental fluvial, playa, and lacustrine sediments may be related to the former Lake Cabesa de Vaca. As there are no record of Rancholabrean (1.02 - 0.01 Ma) sediments in these terrace eroded exposures.
In the Franklins, as a result of the late Cenozoic topographic relief created by the continuing structural uplift and westward tilting of the range surface, landsliding and subsurface gravity gliding occurred throughout the range. Lovejoy (1975) indicates the presence of some 17 gravity glide and landslide brecciated and non-brecciated masses in the Franklins. He interprets the gliding features to be older and primarily confined to the east side of the range (north to south: Pipeline, Anthony's Nose, and Taylor Block gravity glides). Landslides seem to have occurred more recently and on both sides of the range. Examples on the eastern side would include (from north to south): Tin Mine, Sugarloaf, and McMillian landslides; on the western side (from north to south): Anthony, Tom Mays, Smuggler, Flag Hill, and Crazy Cat landslides. It would seem to be reasonable to identify the gliding planes and competency failures to weakly indurated formations. These glide planes and competency failures seem to be logically largely developed in the Ordovician uppermost El Paso Group Florida Mountains Formation, the Late Devonian Percha Shale, and Late Pennsylvanian Panther Seep Formation.
The ancestral Rio Grande in the past flowed through Fillmore Pass and along the eastern side of the Franklins. This can be documented from the gravel pits and water wells in that area. Erosion along Paso del Norte, located on the southwestern side of the Franklins and east of Cerro de Cristo Rey, late in the Pleistocene captured the river by either by stream piracy or a downcutting overflow of lake developed by uplift of the Franklin chains. Tamed by manmade dams in the twentieth century, this magnificent river, the Rio Grande, today is a very poor and insipid imitation of what it was when it was one of the great rivers of the world.
The Franklin Mountains State Park contains a treasure chest of geological history covering over one and one quarter billion years. The Precambrian rocks at the top of North Mount Franklin represent the highest geological structure in the state of Texas. The park has an unparalleled set of accessible exposures. It is a major resource for continuing and future basic research. In applied research, it is of particular importance to the petroleum industry and it's continuing exploration and exploitation of the Permian Basin petroleum province.
In conclusion, as a teaching resource the park's easily accessible outcrops
can and are being used in educational levels ranging from grammar school
to the university doctoral level. Additionally, the park, like Big Bend
or the Carlsbad Caverns, also represents an exceptional opportunity to
be utilized for the visiting general public's geological education as well
as for their recreation.
Evolution of the Modern Landscape
The literature on the Pliocene and Pleistocene of the Franklin Mountains State Park area is in a number of widely scattered regional and national publications. A partial initial recommended selection of the material would include such references as: Kottlowski (1958), Metcalf (n.d.), Hawley and Kottlowski (1969), Hawley (1975), Strain (1958; 1966), Vanderhill (1986), and Lueth et al. (1998).
The modern landscape of the Franklin Mountains is a product of a geologically complex history initiating with the development of extensional Basin-and-Range structure, which in this area has been placed anywhere from 30 to 10 Ma before the present (BP). The contemporaneous development of the Rio Grande rift also had influence on the resulting development of the Franklins and the surrounding marginal bolson areas. This structural activity resulted in the formation of a series of internally draining basins. Regionally, these include the Hueco, Tularosa, Mesilla, and Palomas bolsons. These basins in the late Tertiary accumulated thick deposits of fine-grained lake, playa, and fluvial sediments. The upper section of these is referred to as the Fort Hancock Formation. Periodically, during time of maximum rainfall, the lakes would coalesce into a broad shallow lake with the rising ranges acting as virtual islands in the Franklins area. This periodically coalescing lake, uniting the Hueco and MesiIla bolsons, is called Lake Cabeza de Vaca after the first Spanish explorer in the area. The shorelines of the lake are apparently not preserved in surface outcrop.
During this time the ancestral Rio Grande was forming as individual basins became interconnected. Flow of the river was to the south into the Casas Grandes and/or the Rio Conchos areas of Mexico. This old Rio flowed from the Mesilla bolson to Hueco bolson north of the North Franklin Mountains in the area of Fillmore Pass. This is documented by the water wells exploited and the old gravel quarries (e.g., Bassett Center Mall) on the east side of the Franklins.
After the deposition of the Fort Hancock sediments, a sudden increase in the flow of water from the north occurred as basins down through rift system became interconnected. This is documented by the deposition of the Camp Rice Formation, which is significantly coarser than the underlying Fort Hancock. The lithology is typically fluvial from aggrading stream channels, which produced mixed rounded gravels with exotic pebbles derived from some area other than locally. The Camp Rice in the area is demonstrably coarser to the north and finer to the south in cliffs along the western side of the Rio Grande's Mesilla Valley. Separation between the two formations is in debate in the Mesilla Valley. Some clearly see correlatable coarser clastic Camp Rice unit with a disconformable base traceable from the type area in Hudspeth County, Texas, to the area of Las Cruces in New Mexico. Other researchers do not and simply refer to the entire surface exposure in the Mesilla Valley as Camp Rice. Others would extend the formation down to depths on the order of 200 m (656 ft) based on well interpretation.
The age of the Pliocene-Pleistocene (Fort Hancock and Camp Rice) sediments exposed around the Franklins range in age from 2.5 to 0.6 Ma. These dates are based on the fossil mammalian vertebrate paleontology and magnetostratigraphic studies done primarily on the western side of the range by Vanderhill (1986). Three mammalian faunules were recognized by him; they are, in ascending order: A, B, and C. Faunule A is classified as being late Blancan mammalian age on the presence of the small, three-toed, grazing horse Nannippus peninsulatus. Faunule B has transitional mammalian elements of both the older Blancan and the younger Irvingtonian mammal ages. Faunule C is clearly Irvingtonian based on the presence of Mammuthus (mammoth).
The faunules contain representatives from 14 mammalian families as well as three genera of turtles and a catfish. The mammalian fauna is composed of 90% larger forms, with only rabbit and gopher representing smaller animals. The bulk of the fauna was recovered from fluvial channel deposits. The vertebrate material, while displaying the effects of transport, was largely well preserved, reflecting conditions of rapid burial. The most abundant forms recovered were the horses, which are represented by a long ranging (A, B, C) stilt-legged form (Equus calobatus) and the later (B, C), more abundant, stocky form Equus scotti. Next in abundance are the camels, in which four genera are recognized (Camelops, typically 20 % larger than the present day dromedary; Gigantocamelus; Blancocamelus meadei, a large extremely long limbed camel possibly a relict form of the giraffe camels of the Miocene; and Hemiauchenia blancoensis, the Blanco llama). The extinct, giant, armadillo-like glyptodonts with their distinct scutes were next in abundance. The massive elephant-like, tusked gomphotheres, next in abundance, are represented by Cuvieronius and Stegamastodon. Stegamostodon was typically shorter and stockier than the living Asiatic elephant and stood about 2.4 m (8 ft) at the shoulder. The remainder of the large mammalian fauna includes representatives of mammoth, Nannippus, ground sloth, beaver, bobcat, saber-tooth tiger, tapir, deer, and wolf.
The environment reflected by these faunules was semiarid but much more mesic than that of today. There were moderately large sized braided and meandering stream and river systems with small lakes and playas. The floor of the valley may be interpreted to have been lush, savannah-like grassland with scattered groves of trees and associated more succulent vegetation than would be seen now. Forests would probably have covered the rising Franklin uplands. The area would have been home to herbivorous herds and smaller bands of horses, camels, gomphotheres, mammoths, and deer. The stream bank and riparian faunas are represented in the glyptodonts, beavers, fish, and turtles. Wolves, bobcat, and sabertooth tigers represent the carnivores of this paleobiota. It would take little imagination to consider this fauna and environment to be like a Pleistocene analog of the East African Serengeti.
The mammalian ages of this fauna are in agreement with magnetostratigraphic epoch data which ranges from older latest normal polarity Gauss to reversed Matuyama (2.48-0.73 Ma) to youngest normal Brunhes. The short-lived normal polarity events in the Matuyama reversed polarity Epoch (older to younger) Reunion, Olduavi, and Jaramillo events are noted. The break between the B and C faunules occurs between the Olduavi and Jaramillo events.
The deposition of the coarse clastics in both the Hueco and Mesilla bolsons abruptly halted and vigorous fluvial down cutting took place. It is believed that this is the time in which the Hueco and Mesilla bolsons were interconnected with the Red Light Draw area southeast of El Paso. This allowed the development of an interconnection with the lower part of the Rio Grande enabling the water to drain to the Gulf of Mexico. The upper surface of Camp Rice on the west side of the range is called the La Mesa surface. It can be traced from Mexico, southwest of Anapra, to Las Cruces in New Mexico in the continuous outcrop bounding the western side of the valley.
The Rio Grande may have still flowed through the Fillmore Pass north of the North Franklins. This assumption is questionable based on the newly documented radiometric dating evidence (3.8 Ma and 5.2 Ma) (Lueth et al, 1998) of the uplift from the Webb Gap area in the North Franklin Mountains. The Rio Grande, therefore, assumed its current position as a result of further uplift in the Franklin range and/or by a process of stream piracy through the easily eroded faulted zone at the Pass of the North (also called El Paso Canyon) in the area of the ASARCO Smelter. Once the connection through the Pass between Cristo Rey and the Franklin Mountains was established, the history of the periods of down cutting and deposition are recorded on the west side of the range as a series of paired and unpaired river terraces.
Dating of these terraces and their associated fluvial deposits in conjunction with classic Pleistocene glaciation ages becomes extremely tenuous as some 22 glacial advances and retreats are known to occur in the North America. The cyclic, periglacial, fluvial process of down cutting and deposition follows a well-established system (Schumm, 1965) for glacially influenced semiarid regions. The four stages are: 1) late interglacial, a time of stability; 2) early glacial and full glacial, a time of erosion; 3) late glacial and early interglacial, a time of deposition; and 4) full interglacial, a time of stability.
The terraces have influenced the property value of homes particularly on the west side of the range. The rule is that the most desirable and expensive homes are perched on the La Mesa surface and values decrease terrace by terrace until the floodplain of the river is reached. Real estate values on the floodplain of the Rio Grande dramatically increase again, particularly in the El Paso Country Club area.
The superimposed gravity glides and landslides as well as the uplifted
canyon terraces on the western side of the range stand as mute evidence
to the continuing post-Camp Rice uplift of the Franklins. On the trails
in major arroyos (e.g., Vinton Canyon, McKelligon Canyon, etc.), the terraces
typically offer easy access in comparison to the boulder choked arroyos
paralleling them. On the east side of the range, as can easily be seen
in the Fort Bliss area of Magnetic Avenue, the uplifted benches paralleling
the range offer testimony for continuing tectonic movements in that area.
Literature Cited
Britton, N. L. and J. N. Rose, 1923. The Cactaceae: Carnegie Institution of Washington Publ. 248, 4:56.
City of El Paso, 1970. Franklin Mountains Wilderness Park Master Plan and Long Range Development Guide.
Dempster, L. T., 1973. The polygamous species of the genus Galium (Rubiaceae) section Lophogalium, of Mexico and southwestern United States, Univ. Calif. Publ. in Botany 64:1-36.
Dixon, J. R., 1987. Amphibians and reptiles of Texas: Texas A & M Press, College Station.
Donaldson, W., A. H. Price, and Jack Morse, 1994. The current taxonomic status and future prospects of the Texas horned lizard (Phrynosoma cornutum) in Texas. Texas Journal of Science 46:2 98-113.
Harbour, R. L., 1960. Precambrian rocks at north Franklin Mountain, Texas. American Association of Petroleum Geologists Bulletin, Vol.44:11, p. 1785-1792.
Harbour, R. L., 1972. Geology of the northern Franklin Mountains, Texas and New Mexico: U.S. Geological Survey Bulletin 1298, 129 p..
Hardy, Heck, Moore and Associates, Inc. 1996. Historical narrative and cultural resources survey: Hueco Tanks State Historical Park and Franklin Mountains State Park. Report prepared for Texas Parks and Wildlife Department, Austin.
Hawley, J. W. and F. E. Kottlowski, 1969. Quaternary Geology of South-Central New Mexico Border Region: in Kottlowski, F. E. and D. V. LeMone (eds.), Border Stratigraphy Symposium, New Mexico Bureau of Mines and Mineral Resources, Circular 104, p. 89 - 115.
Hawley, J. W., 1975. Quaternary History of Dona Ana County Region, South-Central New Mexico: in Seager, W. S., R. E. Clemons, and J. F. Callendar (eds.), Las Cruces Country, 26th Field Conference, New Mexico Geological Society, p. 139 - 150.
Johnson, J. D., 1998. Report - 1st year of two year contract (#26799) between El Paso Community College (Jerry D. Johnson, PI) and Texas Parks and Wildlife Department for a comprehensive survey and report of the amphibians, reptiles, and mammals of Hueco Tanks State Historical Park and Franklin Mountains State Park, and recommendations for future research Report to Texas Parks and Wildlife Department, Fort Davis and Austin
Kottlowski, F. E., 1958. Geologic History of the Rio Grande near El Paso: in A. Young, H. L. Williams, J. P. Salisbury, H. N. Freznel, J. P. D. Hull, Jr., and G. L. Evans (eds.), Franklin and Hueco Mountains, Texas, West Texas Geological Society Publication, p. 46 - 54.
Kottlowski, F. E. and D. V. LeMone (eds.) 1969. Border Stratigraphy Symposium, New Mexico Bureau of Mines and Mineral Resources, Circular 104, 123 p.
LeMone, D. V. and E. M. P. Lovejoy (eds.), 1976. Symposium on the Stratigraphy and Structure of the Franklin Mountains, Texas: El Paso Geological Society, 250 p.
LeMone D. V., 1983. Stratigraphy of the Franklin Mountains, El Paso County and Doña Ana County, New Mexico, in R. Allen (ed.), Delaware Basin: West Texas Geological Society, Publication 82-76, p. 26-41.
LeMone D. V., and Ronald D. Simpson, 1983. Cretaceous biostratigraphy of the Franklin Mountains, El Paso County, Texas, in R. Allen (ed.), Delaware Basin: West Texas Geological Society, Publication 82-76, p.85- 87.
LeMone, D. V., 1988. Precambrian and Paleozoic stratigraphy; Franklin Mountains, west Texas: South-Central Section, Geological Society of America, Centennial Field Guidebook Field Guide Volume 4, Papers 87 and 88, p. 387-394.
LeMone, D. V., 1996a, Precambrian Rocks of the Central Franklin Mountains, El Paso County, Texas: in E. Stout (ed,), Precambrian - Devonian Geology of the Franklin Mountains, West Texas - Analogs for Exploration and Production in Ordovician and Silurian Karsted Reservoirs in the Permian Basin, West Texas Geological Society, Publication 96 - 100, p.35 - 46.
LeMone, D. V., 1996b, The Tobosa Basin-Related Stratigraphy of the Franklin Mountains, Texas and New Mexico: in E. Stout (ed,), Precambrian - Devonian Geology of the Franklin Mountains, West Texas - Analogs for Exploration and Production in Ordovician and Silurian Karsted Reservoirs in the Permian Basin, West Texas Geological Society, Publication 96 - 100, p.47 - 70.
Lueth, V. W., P. C. Goodell, M. T. Heizler, and L. Peters, 1998. Geochemistry, Geochronology, and Tectonic Implications of Jarosite Mineralization in the northern Franklin Mountains, Dona Ana County, New Mexico: in 49th Field Conference, New Mexico Geological Society, 309 - 316.
Lovejoy, E. M. P., 1975. An interpretation of the structural geology of the Franklin Mountains, Texas. In Guidebook of the Las Cruces Country, W. R. Seager, R. E. Cleman, and J. F. Callender, eds. 26th Field Conference of New Mexico Geology Society, pp. 261-268.
Lovejoy, E. M. P., 1980. El Paso's Geologic Past: Texas Western Press, El Paso.
McAnulty, W. N., Jr., 1968. Precambrian rocks of the Fusselman Canyon area. in West Texas Geological Society Guidebook, Publication 68-55, pp. 18-25.
Metcalf, A. L. n.d. Gastropod Mollusks (Living Species and Late Quaternary Fossils) of the Franklin Mountains, El Paso County, Texas. Unpublished manuscript prepared for the Texas Natural Area Surveys, Lyndon B. Johnson School of public Affairs, the University of Texas at Austin.
National Park Service. 1992. Western region fire monitoring handbook. USDI National Park Service, San Francisco.
Neck, R. 1986. Environmental Analysis of Franklin Mountains State Park, El Paso County, Texas. Texas Parks and Wildlife Department unpublished report.
Poole, J. M. and W. R. Carr. 1997. Rare plants of Texas, December 1997 edition. Unpublished report to Texas Parks and Wildlife Department, Austin.
Poole, J. M. and D. H. Riskind. 1987. Endangered, threatened, or protected native plants of Texas. Texas Parks and Wildlife Department, Austin.
Schumm, S. A., 1965. Quaternary Paleohydrology: in The Quaternary of the United States, Princeton University Press, p. 783 - 794.
Strain, W. E., 1958. Blancan mammalian fauna from Rio Grande Valley, Hudspeth County, Texas: Geological Society of America Bulletin, Volume 70, p.375 - 378.
Strain, W. E., 1966. Blancan mammalian Fauna and Pleistocene formations, Hudspeth County, Texas: Texas Memorial Museum Bulletin 10, 55p.
Texas Parks and Wildlife Department. 1990. Franklin Mountains State Park, El Paso County, Texas: Summary of Representative Plant Communities: Texas Natural Heritage Program, Austin.
Texas Parks and Wildlife Department., Endangered Resources Branch. 1997. Texas biological and conservation data system special animal list: Unpublished report.
U. S. Fish and Wildlife Service. 1986. Sneed and Lee pincusion cacti (Coryphantha sneedii var. sneedii/Coryphantha sneedii var. leei) recovery plan. U. S. Fish and Wildlife Service, Albuquerque.
Van Devender, T. R. 1885. Climatic cadences and the composition of the Chihuahuan Desert communities: the late Pleistocene packrat midden record. In: Diamond, J. and T. J. Case. Community Ecology. New York: Harper and Rose, Publishers. Pp. 285-299.
Vanderhill, J. B., 1986. Lithostratigraphy, Vertebrate Paleontology, and Magnetostratigraphy of the Plio-Pleisatocene sediments in the Mesilla Basin, New Mexico: Ph. D. Dissertation, University of Texas at Austin, 305 p.
West Texas Geological Society. 1968. Guidebook with Road Logs, Delaware Basin Exploration, West Texas Geological Society Pub. 68-55.
Worthington, R. D., 1995a. Biota of the Franklin Mountains, part 1, fauna. Report to Texas Parks and Wildlife Department. On file at Region I Resource Office, Ft. Davis, TX.
Worthington, R. D., 1995b. Biota of the Franklin Mountains, part II, flora. Report to Texas Parks and Wildlife Department. On file at Region I Resource Office, Ft. Davis, TX.
Worthington, R. D., 1995c. Unique and/or limited resources of Franklin Mountains State Park. Report to Texas Parks and Wildlife Department. On file at Region I Resource Office, Ft. Davis, TX.
Worthington, R. D., 1995d. An overview of the flora of the Franklin Mountains, El Paso County, Texas and Dona Ana county, New Mexico. in Worthington, R. D., Native Plant Society of Texas, p. 56-62.
Zimmer, B.. 1997. Birds of Franklin Mountains State Park: a field checklist.
Texas Parks and Wildlife Department, Natural Resources Program, Austin.
Glossary
Albian - the standard name used for the uppermost stage of the lower Cretaceous.
Andesite - an fine-grained, igneous rock, intermediate in composition between a rhyolite and a basalt.
Aptian - lower Cretaceous stage underlying the Albian.
Basalt - term used to describe a common fine-grained dark extrusive mafic igneous rock.
Basin and range - topography or landscape composed of linear, tilted fault block mountains and ridges separated by broad intervening basins.
Bioherm - a mound or loaf like accumulation of typically composed of organic remains that rises above the sea floor.
Blancan - late Cenozoic mammalian chronostratigraphic fossil zone (5.03 -2.02 Ma).
Bolson - (Spanish for purse) refers to the basin area in basin and range.
Breccia - sedimentary rock composed of gravel size or larger angular fragments.
Carbonates - lithified carbonate muds, normally limestones and or dolomites.
Chaetetid - colonial sponge forming bioherms or biostromes.
Clastics - rocks made up of discrete fragments or clasts.
Complex - term used to describe a complex mixture of igneous and/or metamorphic rocks.
Conglomerate - sedimentary rock composed of gravel size or larger rounded fragments.
Continental - term used to indicate land origin
Correlation - A general term for the use of fossils or special characteristics of the rock to establish that spatially separated stratigraphic units are equivalent.
Cyclostratigraphy - The concept in stratigraphy that carbonate deposition is separable into recognizable hierarchical.
Dolomite - a carbonate mineral and rock type (also called a dolostone) composed of a calcium - magnesium carbonate.
Equatorial - an environmental belt, normally defined as 15 degrees north or south of the geographical equator.
Extrusive - term used to describe igneous rocks which has been erupted onto the earth's surface.
Fault - a surface or zone of rock fracture along which there has been displacement of varying distances and in any direction.
Faunule - a term normally used to describe an assemblage of fossil animals associated with a specific set of strata and dominated by the representatives of one fossil community.
Felsite - a light colored fine-grained igneous rock.
Fluvial - term used to describe the river and stream environment.
Formation - basic stratigraphic term defined as a distinct mappable rock unit.
Geosyncline - general term for an elongate, downwarped portion of the crust which is or has been accumulating a thick sequence of sedimentary and/or volcanic rocks.
Hornfels - a term used to describe a fine-grained, granular metamorphic rock.
Ignimbrite - welded (ash hot enough to be welded together) and non-welded (air fall) tuffs from a nuee ardente.
Intrusive - a rock formed from cooling of a magma in the crust.
Irvingtonian - late Cenozoic mammalian chronostratigraphic fossil zone (2.02 - 1.02 Ma).
Jarosite - an ocher-yellow to brown hydrated potassium iron sulfate mineral utilized for radioactive dating.
Lacustrine -term used to indicate a lake environment.
Laramide orogeny - orogenic events involving in mountain building in the western United States ranging in time between the Late Cretaceous and the early Cenozoic.
Limestone - a sedimentary rock dominantly composed of calcium carbonate.
Marble - the product of the metamorphism of limestones and/or dolomites.
Marine - environmental term used to indicate sea or oceanic.
Mesoproterozoic - term used to describe the Middle Proterozoic Era (1000 - 1600 Ma).
Metaigneous - metamorphosed igneous rocks.
Metasediment - metamorphosed sedimentary rocks.
Nonconformity - an unconformity separating bedded rocks above from crystalline igneous and/or metamorphic rocks below. (see unconformity).
Nuee ardente - (French = glowing cloud) turbulent, incandescent gas cloud erupted from a volcano (also called a Pelean cloud).
Orogeny - the process by which structures within mountain areas were formed.
Orogrande basin - late Paleozoic sedimentary basin formed in south-central New Mexico, west Texas, and northern Chihuahua.
Pangean supercontinent - continent formed during the late Paleozoic and eventually fragmented into the continental distribution observed today.
Phylloid algae - calcareous codiacean green algae with leaf-like thalli, also referred to as potato chip algae. Accumulations of these thalli form important petroleum reservoirs in the late Paleozoic.
Playa - temporary lake formed in a basin or region of interior drainage.
Proterozoic - Eon of Precambrian time from 2.5 billion years to the base of the Cambrian. It is divided into three eras and ten periods that are classified on the basis of their radiometric ages.
Riparian - term meaning pertaining to or situated on a bank of a body of water, normally fluvial.
Quartzite - term utilized for predominantly quartz sandstone cemented with quartz.
Rancholabrean - late Cenozoic mammalian biostratigraphic fossil zone (1.02-0.01 Ma).
Savannah - general term for a grass land with scattered trees.
Scute - as used, a bony plate, usually hexagonal in shape from a glyptodon carapace.
Siliciclastic - clastic sediments composed almost exclusively of quartz and/or silicate minerals.
Source rock - sedimentary rock containing organic material which under heat, pressure, and time is convertible into gaseous and liquid hydrocarbons.
Stratotype - the originally described type section of a formation.
Strata - distinct sedimentary beds or layers (singular = stratum).
Stream piracy - headward erosion of one stream capturing the flow of another stream.
Syncline - structural term used to describe a downwardly bent or flexed fold of rocks.
Tectonic - that segment of structural geology involved with the development and interpretation of large-scale activities (e.g., mountain building).
Tethys - the sea that existed for long periods of geologic time that separated the northern and southern continental land masses of the eastern hemisphere. Its trace ran through the Mediterranean area basically along the present day Alpine - Himalayan orogenic belt.
Tobosa basin - name given for the early and middle Paleozoic shallow marine continental margin of the Texas region.
Transitional - sediments formed between the land and the sea.
Tuff - term used for a compacted extrusive pyroclastic deposit of volcanic ash and/or dust.
Turbidite - a graded bed often with poorly sorted coarse clastics (e.g., sand) at the base becoming finer (mud) at the top caused by the turbidity current slowing down.
Turonian - a standard stage name used in the Upper Cretaceous.
Unconformity - a major non-depositional or erosional break in the rock record. Three types of are normally recognized:
Xenolith - term used for an inclusion in an igneous rock that is not genetically related to the igneous rock.
