Tule Springs Research Articles

Conodont thermochronology of exhumed footwalls of low-angle normal faults: A pilot study in the Mormon Mountains, Tule Springs Hills, and Beaver Dam Mountains, southeastern Nevada and southwestern Utah

(U-Th)/He thermochronology is a well-established dating technique used to understand the temperature-time histories of rocks in a wide range of geologic settings. The technique is presently restricted to rocks that contain specific accessory minerals, such as apatite or zircon. Marine carbonates and shales typically lack these accessory phases in quantities and sizes practical for (U-Th)/He dating and thus present a challenge for application of the method. Here, we explore the utility of biogenic apatite from conodonts as a (U-Th)/He thermochronometer at a well-studied calibration site located in eastern Nevada and southwestern Utah.We performed (U-Th)/He thermochronometry, laser ablation inductively coupled plasma mass spectrometry, X-ray micro-computed tomography, and scanning electron microscopy (SEM) on specimens with conodont color alteration indices (CAI) of 1.5–3, extracted from carbonate rocks in the footwalls of low-angle normal faults in the Mormon Mountains, Tule Spring Hills, and Beaver Dam Mountains. Conodont (U-Th)/He (CHe) dates have high scatter; dates are commonly reproducible to 20% of sample means but can deviate up to 150%. All CAI 1.5–2.5 conodonts produce CHe dates younger than 240 Ma, consistent with thermal resetting of samples; however, most CAI 3 conodonts give ages 2–6× older than Mississippian and Permian deposition. Average U, Th, and rare earth element (REE) concentrations depend on porosity and permeability differences between albid and hyaline conodont tissue and range from <10 to 100 s of ppm in concentration. Parent isotope concentrations are especially low in CAI 3 conodonts, commonly <1 ppm, and there is an inverse relationship between these concentrations and CHe dates. The majority of parent U, Th, and Sm and REEs are concentrated within the outer 5 μm of the conodont elements and consistently show 5–10× enrichment relative to cores. Margin enrichment is also depressed with increasing CAI. SEM imaging shows a shift in the orientation of apatite microcrystallites from perpendicular to parallel to the major axes of the conodont elements at CAI 3 and corrosion and recrystallization features, likely associated with burial and diagenesis, on the surfaces of some CAI 2.5 and 3 conodonts.We propose that microstructural changes associated with increasing CAI influence CHe dates. Parent isotope loss occurs during the post-cooling stage, either in the outcrop or in the laboratory. Our hypothesis is that the double-buffered formic acid procedure for dissolving dolomitized carbonates may accelerate this loss in thermally altered, higher CAI conodonts.

The Tule Springs local fauna: Rancholabrean vertebrates from the Las Vegas Formation, Nevada

A middle to late Pleistocene sedimentary sequence in the upper Las Vegas Wash, north of Las Vegas, Nevada, has yielded the largest open-site Rancholabrean vertebrate fossil assemblage in the southern Great Basin and Mojave Deserts. Recent paleontologic field studies have led to the discovery of hundreds of fossil localities and specimens, greatly extending the geographic and temporal footprint of original investigations in the early 1960s. The significance of the deposits and their entombed fossils led to the preservation of 22,650 acres of the upper Las Vegas Wash as Tule Springs Fossil Beds National Monument. These discoveries also warrant designation of the assemblage as a local fauna, named for the site of the original paleontologic studies at Tule Springs.The large mammal component of the Tule Springs local fauna is dominated by remains of Mammuthus columbi as well as Camelops hesternus, along with less common remains of Equus (including E. scotti) and Bison. Large carnivorans including Canis dirus, Smilodon fatalis, and Panthera atrox are also recorded. Micromammals, amphibians, lizards, snakes, birds, invertebrates, plant macrofossils, and pollen also occur in the deposits and provide important and complementary paleoenvironmental information. The fauna occurs within the Las Vegas Formation, an extensive and stratigraphically complex sequence of groundwater discharge deposits that represent a mosaic of desert wetland environments. Radiometric and luminescence dating indicates the sequence spans the last ∼570 ka, and records hydrologic changes in a dynamic and temporally congruent response to northern hemispheric abrupt climatic oscillations. The vertebrate fauna occurs in multiple stratigraphic horizons in this sequence, with ages of the fossils spanning from ∼100 to ∼12.5 ka.

Vertebrate paleontology, stratigraphy, and paleohydrology of Tule Springs Fossil Beds National Monument, Nevada (USA)

Tule Springs Fossil Beds National Monument (TUSK) preserves 22,650 acres of the upper Las Vegas Wash in the northern Las Vegas Valley (Nevada, USA). TUSK is home to extensive and stratigraphically complex groundwater discharge (GWD) deposits, called the Las Vegas Formation, which represent springs and desert wetlands that covered much of the valley during the late Quaternary. The GWD deposits record hydrologic changes that occurred here in a dynamic and temporally congruent response to abrupt climatic oscillations over the last ~300 ka (thousands of years). The deposits also entomb the Tule Springs Local Fauna (TSLF), one of the most significant late Pleistocene (Rancholabrean) vertebrate assemblages in the American Southwest. The TSLF is both prolific and diverse, and includes a large mammal assemblage dominated by Mammuthus columbi and Camelops hesternus. Two (and possibly three) distinct species of Equus, two species of Bison, Panthera atrox, Smilodon fatalis, Canis dirus, Megalonyx jeffersonii, and Nothrotheriops shastensis are also present, and newly recognized faunal components include micromammals, amphibians, snakes, and birds. Invertebrates, plant macrofossils, and pollen also occur in the deposits and provide important and complementary paleoenvironmental information. This field compendium highlights the faunal assemblage in the classic stratigraphic sequences of the Las Vegas Formation within TUSK, emphasizes the significant hydrologic changes that occurred in the area during the recent geologic past, and examines the subsequent and repeated effect of rapid climate change on the local desert wetland ecosystem.

Geologic map of the east-central Meadow Valley Mountains, and implications for reconstruction of the Mormon Peak detachment, Nevada

The role of low-angle faults in accommodating extension within the upper crust remains controversial because the existence of these faults markedly defies extant continuum theories of how crustal faults form, and once initiated, how they continue to slip. Accordingly, for many proposed examples, basic kinematic problems like slip direction, dip angle while active, and magnitude of offset are keenly debated. A well-known example is the Miocene Mormon Peak detachment and overlying Mormon Peak allochthon of southern Nevada (USA), whose origin and evolution have been debated for several decades. Here, we use geologic mapping in the Meadow Valley Mountains to help define the geometry and kinematics of emplacement of the Mormon Peak allochthon, the hanging wall of the Mormon Peak detachment. Pre-exten­sion structural markers, inherited from the east-vergent Sevier thrust belt of Meso­zoic age, are well suited to constrain the geometry and kine­matics of the detachment. In this study, we add to these markers a newly mapped Sevier-­age monoclinal flexure preserved in the hanging wall of the detachment. The bounding axial surfaces of the flexure can be readily matched to the base and top of the frontal Sevier thrust ramp, which is exposed in the footwall of the detachment to the east in the Mormon Mountains and Tule Springs Hills. Multiple proxies for the slip direction of the detachment, including the mean tilt direction of hanging wall fault blocks, the trend of striations measured on the fault plane, and other structural features, indicate that it is approximately S77°W (257°). Given the observed structural separation lines between the hanging wall and footwall, this slip direction indicates 12–13 km of horizontal displacement on the detachment (14–15 km net slip), lower than a previous estimate of 20–22 km, which was based on erroneous assumptions in regard to the geometry of the thrust system. Based on a new detailed map compilation of the region and recently published low-temperature thermochronologic data, palinspastic constraints also preclude earlier suggestions that the Mormon Peak allochthon is a composite of diachronously emplaced, surficial landslide deposits. Although earlier suggestions that the initiation angle of the detachment in the central Mormon Mountains is ∼ 20°–25° remain valid, the geometry of the Sevier-age monocline in the Meadow Valley Mountains and other structural data suggest that the initial dip of the detachment steepens toward the north beneath the southernmost Clover Mountains, where the hanging wall includes kilometer-scale accumulations of volcanic and volcaniclastic strata.

Vertebrate paleontology, stratigraphy, and paleohydrology of Tule Springs Fossil Beds National Monument, Nevada (USA)

Tule Springs Fossil Beds National Monument (TUSK) preserves 22,650 acres of the upper Las Vegas Wash in the northern Las Vegas Valley (Nevada, USA). TUSK is home to extensive and stratigraphically complex groundwater discharge (GWD) deposits, called the Las Vegas Formation, which represent springs and desert wetlands that covered much of the valley during the late Quaternary. The GWD deposits record hydrologic changes that occurred here in a dynamic and temporally congruent response to abrupt climatic oscillations over the last ~300 ka (thousands of years). The deposits also entomb the Tule Springs Local Fauna (TSLF), one of the most significant late Pleistocene (Rancholabrean) vertebrate assemblages in the American Southwest. The TSLF is both prolific and diverse, and includes a large mammal assemblage dominated by Mammuthus columbi and Camelops hesternus. Two (and possibly three) distinct species of Equus, two species of Bison, Panthera atrox, Smilodon fatalis, Canis dirus, Megalonyx jeffersonii, and Nothrotheriops shastensis are also present, and newly recognized faunal components include micromammals, amphibians, snakes, and birds. Invertebrates, plant macrofossils, and pollen also occur in the deposits and provide important and complementary paleoenvironmental information. This field compendium highlights the faunal assemblage in the classic stratigraphic sequences of the Las Vegas Formation within TUSK, emphasizes the significant hydrologic changes that occurred in the area during the recent geologic past, and examines the subsequent and repeated effect of rapid climate change on the local desert wetland ecosystem.

Preserving fossils in the national parks: A history

ABSTRACT The fossil record preserved throughout the National Park Service spans more than a billion years and is documented in at least 267 park units. The discovery, collection, study, and resource management of fossils from localities which are currently within parks sometimes predate the establishment of the National Park Service and many of the parks. Public education and interpretation at parks such as Agate Fossil Beds and Tule Springs Fossil Beds national monuments and many other designated areas include information on the rich history of paleontological field work by notable paleontologists undertaken prior to the areas being preserved as national park areas. Another important historical aspect for several dozen parks involves the conservation efforts undertaken by the public and interest groups to preserve and protect these important fossil localities. The evolution of the science and methodologies in paleontology is reflected in the resource management undertaken by the National Park Service and documented in park resource management records and archives, scientific publications, and agency policy. Today the National Park Service celebrates fossils by coordinating the National Fossil Day partnership which helps to promote the scientific and educational value of fossils.

First records of Canis dirus and Smilodon fatalis from the late Pleistocene Tule Springs local fauna, upper Las Vegas Wash, Nevada.

Late Pleistocene groundwater discharge deposits (paleowetlands) in the upper Las Vegas Wash north of Las Vegas, Nevada, have yielded an abundant and diverse vertebrate fossil assemblage, the Tule Springs local fauna (TSLF). The TSLF is the largest open-site vertebrate fossil assemblage dating to the Rancholabrean North American Land Mammal Age in the southern Great Basin and Mojave Desert. Over 600 discrete body fossil localities have been recorded from the wash, including an area that now encompasses Tule Springs Fossil Beds National Monument (TUSK). Paleowetland sediments exposed in TUSK named the Las Vegas Formation span the last 250 ka, with fossiliferous sediments spanning ∼100–13 ka. The recovered fauna is dominated by remains of Camelopsand Mammuthus, and also includes relatively common remains of extinct Equusand Bisonas well as abundant vertebrate microfaunal fossils. Large carnivorans are rare, with only Puma concolor and Panthera atrox documented previously. Postcranial remains assigned to the species Canis dirus (dire wolf) and Smilodon fatalis (sabre-toothed cat) represent the first confirmed records of these species from the TSLF, as well as the first documentation of Canis dirus in Nevada and the only known occurrence of Smilodonin southern Nevada. The size of the recovered canid fossil precludes assignment to other Pleistocene species of Canis. The morphology of the felid elements differentiates them from other large predators such as Panthera, Homotherium, and Xenosmilus, and the size of the fossils prevents assignment to other species of Smilodon. The confirmed presence of S. fatalis in the TSLF is of particular interest, indicating that this species inhabited open habitats. In turn, this suggests that the presumed preference of S. fatalis for closed-habitat environments hunting requires further elucidation.

Low-temperature thermochronologic constraints on the kinematic histories of the Castle Cliffs, Tule Springs, and Mormon Peak detachments, southwestern Utah and southeastern Nevada

We use apatite and zircon (U-Th)/He thermochronometry to evaluate the timing, magnitude, and spatial pattern of Miocene strain within the Beaver Dam Mountains, Tule Springs Hills, and Mormon Mountains of southwestern Utah and southeastern Nevada (USA). The region is host to three major low-angle structures, the Castle Cliffs, Tule Springs, and Mormon Peak detachments, the origin and role of which in regional extension are vigorously debated. We analyzed 36 samples collected from Precambrian basement gneisses and Paleozoic to Jurassic siltstones and sandstones exposed in the footwalls of these detachments. Zircon He ages from the footwall of the Castle Cliffs detachment record rapid footwall exhumation ca. 18–17 Ma. At structurally higher positions, apparent ages become progressively older, defining a zircon He partial retention zone. Paleodepth reconstructions of the data using published cross sections suggest 180 °C, or greater, of cooling or 6.8–8.2 km of total exhumation, yielding a maximum of ∼13 km of extension across this detachment. In contrast, zircon and apatite ages from the footwall of the Mormon Peak record rapid exhumation at 14–13 Ma and 5.8–7.1 km of vertical exhumation. Using a range of restored fault dips (20°–28°) for the Mormon Peak detachment, the thermochronology data record 10.9–19.5 km horizontal extension. Data from the Tule Springs detachment also show a similar timing of exhumation and indicate that there has been 5.0–6.8 km of vertical exhumation and a minimum of ∼5 km of extension. The results demonstrate that extension initiated in the east along the Castle Cliffs detachment and migrated westward with time. Although our data indicate that existing extension estimates across this system of detachment faults are too high (40 km versus 54 km), the pattern of cooling ages and protracted cooling history recorded in these ranges are inconsistent with rootless gravity slide interpretations and low-magnitude extension models.

Did Pre-Clovis People Inhabit the Paisley Caves (and Why Does It Matter)?

Did Pre-Clovis People Inhabit the Paisley Caves (and Why Does It Matter)? Stuart J. Fiedel key words Paisley Caves, Pre-Clovis, Western Stemmed, Ancient DNA, Coprolites The date and processes of initial human colonization of the Americas are crucial issues for the understanding of human biological and cultural development. For example, Soares et al. (2009) cited the American archaeological record to validate their proposed revision of the human mitochondrial molecular clock. Their suggested mutation rate puts the date of rapid expansion of Native American clades at around 13,500–15,000 cal yr BP. Similarly, Poznik et al. (2013) have used the “high-confidence archaeological dating” of the initial peopling of the Americas to calibrate the rates of both Y-chromosome and mitochondrial DNA (mtDNA) mutation and thereby to reconcile the ages of the common ancestors of human males and females. They use a date of ~15,000 cal yr BP, based on purported archaeological evidence from Monte Verde, Chile, dated to 14,600 cal yr BP. Until recently, the consensus of archaeologists was that the Americas were populated after 13,400 cal yr BP (11,500 14C yr BP) by a rapid expansion of people bearing the Clovis culture. Clovis ancestors, originating in southern Siberia, had crossed Beringia around 14,500 cal yr BP and subsequently migrated through a corridor between the receding Laurentide and Cordilleran ice sheets. This “Clovisfirst” model has been challenged continually by advocates for various allegedly pre-Clovis sites. As the evidence for a given set of ostensibly promising sites fails to withstand close critical scrutiny (e.g., Tule Springs, Pikimachay, Pendejo Cave, Pedra Furada, Shriver, etc.), pre-Clovis enthusiasts pin their hopes on the latest contenders. Currently, their favorites are Monte Verde in southern Chile (Dillehay 1997; Dillehay et al. 2008), the Debra L. Friedkin site in Texas (Waters et al. 2011), and the Paisley Caves in southern Oregon. The evidence from both Monte Verde and Paisley Caves has been deployed both by archaeologists (e.g., Beck and Jones 2010; Erlandson and Braje 2011) and by geneticists (e.g., Bodner et al. 2012) in support of a model of pre-Clovis migration along the Pacific coast—this despite the continuing absence of any sites older than 13,200 cal yr BP along the entire coast from Alaska to Tierra del Fuego (Dickinson 2011). The Paisley Caves pre-Clovis evidence is unique in that it consists of both artifacts and directly dated ancient feces that have yielded human DNA. Gilbert et al. (2008) reported coprolites containing human (but also canid) mtDNA dating to ~14,300 cal yr BP. Poinar et al. (2009) noted chronological and stratigraphic problems and suggested that contamination by leaching might account for possibly exogenous human DNA in the coprolites, while Goldberg et al. (2009) (who had actually examined and sampled the coprolites) asserted that their morphology was inconsistent with human derivation. Jenkins et al. (2012a, 2014) report results of meticulous excavations and analyses designed to verify their previous claims. This research focused particularly on demonstrating that the radiocarbon dates are accurate and that the coprolites have [End Page 69] not been contaminated by leaching. Jenkins and colleagues now assert that diagnostic Western Stemmed Tradition (WST) lithic artifacts and associated human coprolites date between 11,070 and 11,340 14C yr BP (~13,000–13,300 cal yr BP). The artifact-associated radiocarbon dates overlap with dates for Clovis elsewhere (11,550–10,800 14C yr BP), while additional purported human coprolites are of pre-Clovis age (older than 11,600 14C yr BP). This entire assemblage is interpreted as conclusive evidence that “the colonization of the Americas involved multiple technologically divergent, and possibly genetically divergent, founding groups” (Jenkins et al. 2012a: 223). Close examination of the reported data shows that three stratigraphically and chronologically discrete components are present in the deep strata (Jenkins et al. 2014). The deepest deposit attributed to human activity consists entirely of coprolites, with no associated unambiguous lithic or organic artifacts. These purported “human” coprolites (dated to ~14,000–14,400 cal yr BP) are intermixed with others attributed, based on DNA, to late Pleistocene animals, that is, camelids and lion (Panthera...

Did pre-Clovis people inhabit the Paisley Caves (and why does it matter)?

The date and processes of initial human colonization of the Americas are crucial issues for the understanding of human biological and cultural development. For example, Soares et al. (2009) cited the American archaeological record to validate their proposed revision of the human mitochondrial molecular clock. Their suggested mutation rate puts the date of rapid expansion of Native American clades at around 13,500–15,000 cal yr BP. Similarly, Poznik et al. (2013) have used the “high-confidence archaeological dating” of the initial peopling of the Americas to calibrate the rates of both Y-chromosome and mitochondrial DNA (mtDNA) mutation and thereby to reconcile the ages of the common ancestors of human males and females. They use a date of ~15,000 cal yr BP, based on purported archaeological evidence from Monte Verde, Chile, dated to 14,600 cal yr BP. Until recently, the consensus of archaeologists was that the Americas were populated after 13,400 cal yr BP (11,500 C yr BP) by a rapid expansion of people bearing the Clovis culture. Clovis ancestors, originating in southern Siberia, had crossed Beringia around 14,500 cal yr BP and subsequently migrated through a corridor between the receding Laurentide and Cordilleran ice sheets. This “Clovisfirst” model has been challenged continually by advocates for various allegedly pre-Clovis sites. As the evidence for a given set of ostensibly promising sites fails to withstand close critical scrutiny (e.g., Tule Springs, Pikimachay, Pendejo Cave, Pedra Furada, Shriver, etc.), pre-Clovis enthusiasts pin their hopes on the latest contenders. Currently, their favorites are Monte Verde in southern Chile (Dillehay 1997; Dillehay et al. 2008), the Debra L. Friedkin site in Texas (Waters et al. 2011), and the Paisley Caves in southern Oregon. The evidence from both Monte Verde and Paisley Caves has been deployed both by archaeologists (e.g., Beck and Jones 2010; Erlandson and Braje 2011) and by geneticists (e.g., Bodner et al. 2012) in support of a model of pre-Clovis migration along the Pacific coast—this despite the continuing absence of any sites older than 13,200 cal yr BP along the entire coast from Alaska to Tierra del Fuego (Dickinson 2011). The Paisley Caves pre-Clovis evidence is unique in that it consists of both artifacts and directly dated ancient feces that have yielded human DNA. Gilbert et al. (2008) reported coprolites containing human (but also canid) mtDNA dating to ~14,300 cal yr BP. Poinar et al. (2009) noted chronological and stratigraphic problems and suggested that contamination by leaching might account for possibly exogenous human DNA in the coprolites, while Goldberg et al. (2009) (who had actually examined and sampled the coprolites) asserted that their morphology was inconsistent with human derivation. Jenkins et al. (2012a, 2014) report results of meticulous excavations and analyses designed to verify their previous claims. This research focused particularly on demonstrating that the radiocarbon dates are accurate and that the coprolites have

Did Pre-Clovis People Inhabit the Paisley Caves (and Why Does It Matter)?

Did Pre-Clovis People Inhabit the Paisley Caves (and Why Does It Matter)? Stuart J. Fiedel key words Paisley Caves, Pre-Clovis, Western Stemmed, Ancient DNA, Coprolites The date and processes of initial human colonization of the Americas are crucial issues for the understanding of human biological and cultural development. For example, Soares et al. (2009) cited the American archaeological record to validate their proposed revision of the human mitochondrial molecular clock. Their suggested mutation rate puts the date of rapid expansion of Native American clades at around 13,500–15,000 cal yr BP. Similarly, Poznik et al. (2013) have used the “high-confidence archaeological dating” of the initial peopling of the Americas to calibrate the rates of both Y-chromosome and mitochondrial DNA (mtDNA) mutation and thereby to reconcile the ages of the common ancestors of human males and females. They use a date of ~15,000 cal yr BP, based on purported archaeological evidence from Monte Verde, Chile, dated to 14,600 cal yr BP. Until recently, the consensus of archaeologists was that the Americas were populated after 13,400 cal yr BP (11,500 14C yr BP) by a rapid expansion of people bearing the Clovis culture. Clovis ancestors, originating in southern Siberia, had crossed Beringia around 14,500 cal yr BP and subsequently migrated through a corridor between the receding Laurentide and Cordilleran ice sheets. This “Clovisfirst” model has been challenged continually by advocates for various allegedly pre-Clovis sites. As the evidence for a given set of ostensibly promising sites fails to withstand close critical scrutiny (e.g., Tule Springs, Pikimachay, Pendejo Cave, Pedra Furada, Shriver, etc.), pre-Clovis enthusiasts pin their hopes on the latest contenders. Currently, their favorites are Monte Verde in southern Chile (Dillehay 1997; Dillehay et al. 2008), the Debra L. Friedkin site in Texas (Waters et al. 2011), and the Paisley Caves in southern Oregon. The evidence from both Monte Verde and Paisley Caves has been deployed both by archaeologists (e.g., Beck and Jones 2010; Erlandson and Braje 2011) and by geneticists (e.g., Bodner et al. 2012) in support of a model of pre-Clovis migration along the Pacific coast—this despite the continuing absence of any sites older than 13,200 cal yr BP along the entire coast from Alaska to Tierra del Fuego (Dickinson 2011). The Paisley Caves pre-Clovis evidence is unique in that it consists of both artifacts and directly dated ancient feces that have yielded human DNA. Gilbert et al. (2008) reported coprolites containing human (but also canid) mtDNA dating to ~14,300 cal yr BP. Poinar et al. (2009) noted chronological and stratigraphic problems and suggested that contamination by leaching might account for possibly exogenous human DNA in the coprolites, while Goldberg et al. (2009) (who had actually examined and sampled the coprolites) asserted that their morphology was inconsistent with human derivation. Jenkins et al. (2012a, 2014) report results of meticulous excavations and analyses designed to verify their previous claims. This research focused particularly on demonstrating that the radiocarbon dates are accurate and that the coprolites have [End Page 69] not been contaminated by leaching. Jenkins and colleagues now assert that diagnostic Western Stemmed Tradition (WST) lithic artifacts and associated human coprolites date between 11,070 and 11,340 14C yr BP (~13,000–13,300 cal yr BP). The artifact-associated radiocarbon dates overlap with dates for Clovis elsewhere (11,550–10,800 14C yr BP), while additional purported human coprolites are of pre-Clovis age (older than 11,600 14C yr BP). This entire assemblage is interpreted as conclusive evidence that “the colonization of the Americas involved multiple technologically divergent, and possibly genetically divergent, founding groups” (Jenkins et al. 2012a: 223). Close examination of the reported data shows that three stratigraphically and chronologically discrete components are present in the deep strata (Jenkins et al. 2014). The deepest deposit attributed to human activity consists entirely of coprolites, with no associated unambiguous lithic or organic artifacts. These purported “human” coprolites (dated to ~14,000–14,400 cal yr BP) are intermixed with others attributed, based on DNA, to late Pleistocene animals, that is, camelids and lion (Panthera...

Twilight of the mammoths: Ice Age extinctions and the rewilding of America

List of Illustrations Acknowledgments Prologue 1 Discovering the Last Lost World Radiocarbon Dating and Quaternary Extinctions 2 Overview of Overkill 3 Ground Sloth Dung and Packrat Middens Giant Meat-Eating Bats? 4 Ground Sloths at Home Cryptozoology, Ground Sloths, and Mapinguari National Park 5 Grand Canyon Suite: Mountain Goats, Condors, Equids, and Mammoths 6 Deadly Syncopation 7 Digging for the First People in America: High Stakes at Tule Springs Tricks, Hoaxes, and Bad Science 8 Kill Sites, Sacred Sites 9 Models in Collision: Climatic Change versus Overkill 10 Restoration Unexpected Ramifications of Ecological Change 11 Resurrection: The Past Is Future Epilogue References Index

Ramp-flat detachment faulting and low-angle normal reactivation of the Tule Springs thrust, southern Nevada

Research Article| August 01, 1993 Ramp-flat detachment faulting and low-angle normal reactivation of the Tule Springs thrust, southern Nevada GARY J. AXEN GARY J. AXEN 1Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Baja California, Mexico Search for other works by this author on: GSW Google Scholar GSA Bulletin (1993) 105 (8): 1076–1090. https://doi.org/10.1130/0016-7606(1993)105<1076:RFDFAL>2.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation GARY J. AXEN; Ramp-flat detachment faulting and low-angle normal reactivation of the Tule Springs thrust, southern Nevada. GSA Bulletin 1993;; 105 (8): 1076–1090. doi: https://doi.org/10.1130/0016-7606(1993)105<1076:RFDFAL>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Detailed geological mapping of the southern and central Tule Springs Hills and northern East Mormon Mountains, Nevada, reveals details of the interaction between a Mesozoic thrust system and Tertiary detachment faults. The main structure in the area is the subhorizontal Tule Springs detachment, along which a highly deformed hanging wall of Paleozoic and sparse Tertiary strata overlies a much less deformed footwall of Permian to Jurassic beds. The hanging wall was emplaced in Mesozoic time along a décollement-style thrust with a ramp-flat footwall geometry, then extended in Neogene time synchronous with normal reactivation of the flat and upper part of the ramp. Below that point the detachment diverged from the thrust ramp, cutting more steeply into the thrust footwall, forming a similar ramp-flat detachment geometry. The Middle Member of the Jurassic Kayenta Formation forms the flat, for ∼14 km in the Tertiary transport direction. This part of the detachment dipped 3°-15° toward the transport direction and was shallower than 5 km at the onset of normal slip. Much slip may have occurred in weak subjacent siltstone. The detachment ramp is also now subhorizontal, having been rotated from an initial moderate west dip, probably due to isostatic rebound during tectonic unloading along the ramp. Permian to Jurassic strata beneath the detachment ramp in the southwestern Tule Springs Hills now dip moderately east-northeast, having been tilted from subhorizontal while the detachment ramp was flattened. Those beds now form the west limb of a range-scale asymmetric syncline, and footwall beds below the detachment flat form the east limb. In the northern East Mormon Mountains, the detachment is represented by the Toquop Chaos fault zone, which cuts downsection through lower Paleozoic strata that also probably belong in the west limb of the syncline, beneath the detachment ramp. The basal nonconformity there dips east also, so the syncline deformed the entire stratified sequence and the underlying crystalline basement.A large klippe of the detachment (∼185 km2) is characterized by north- trending ridges and valleys ∼2 km wide. These are bounded by moderately dipping or listric normal faults, many of which demonstrably end at, or merge with, the detachment. The topography of the klippe mimics the linear basins and ranges of the Great Basin at a smaller scale. If the structural style is also analogous, then many Great Basin range-valley pairs may be underlain by detachments at relatively shallow depths, rather than being bounded by deeply penetrating faults.Large north-striking faults that cut the Tule Springs detachment control range- scale topography, are each several kilometers long, and cut all other structures in the map area. They postdate detachment slip. One of them cuts Pliocene(?) calcrete-cemented alluvium that is younger than the detachment, and another has ∼8 km of left-lateral offset. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Zoogeography and paleozoology of leeches, molluscs, and amphibians in Western Bonneville Basin, Utah, USA

The artesian springs of Tule Valley are similar to those of adjacent Snake Valley and Fish Springs Flat based on conductivity and temperature. All three valleys support Ranidae amphibians and the leechErpobdella punctata. The artesian springs in Snake Valley and Fish Springs Flat contain six and two species of fish and contained up to 18 and 12 species of mollusk respectively, whereas Tule Valley artesian springs contain neither fish nor mollusks. The leechesHelobdella stagnalis, Glossiphonia complanata, andHaemopis grandis were found in Snake Valley whereasHelobdella triserialis, Theromyzon rude, andHaemopis marmorata were found in Tule Valley. These springs which were covered by Lake Bonneville to a depth of several hundred meters, 16 000 BP., became isolated after the paleolake desiccated 13 000 years BP. The marsh snailCatinella is found above the paleolake level in Snake and Tule Valley and has not penetrated to the valley floor habitats once covered by the paleolake, whereas another marsh snailOxyloma has penetrated into these habitats in Snake Valley. The leech and molluscan distributions in Tule, Snake and Fish Springs Valleys suggest that the paleolake did not allow for much movement among the valleys, and successful passive aerial transport has not occurred after the paleolake desiccation 13 000 years BP. Paleozoological models are proposed to explain the presence and absence of these species in Tule Valley. Both lateral movement (along paleolake shorelines) and vertical movement (to new habitats formed after the desiccation of the paleolake) by amphibians, mollusks and leeches is restricted in large terminal lakes and is species dependent in both spatial and temporal scales of the hydrological cycle.

Late quaternary environmental changes in the upper Las Vegas valley, Nevada

Five stratigraphic units and five soils of late Pleistocene to Holocene age crop out in dissected badlands on Corn Creek Flat, 30 km northwest of Las Vegas, Nevada, and at Tule Springs, nearer to Las Vegas. The record is dominantly fluvial but contains evidence of several moister, marsh-forming periods: the oldest (Unit B) dates perhaps to the middle Wisconsin, and the more widespread Unit D falls between 30,000 and 15,000 yr B.P. Unit D therefore correlates with pluvial maximum lacustrine deposits elsewhere in the Great Basin. Standing water was not of sufficient depth or extent during either period to form lake strandlines. Between 14,000 and 7200 yr B.P. (Unit E), standing surface water gradually decreased, a trend also apparent in Great Basin pluvial lake chronologies during the same period. Groundwater carbonate cementation and burrowing by cicadas (Cicadae) accompany the moist-phase units. After 7200 yr B.P., increased wind action, decreased biotic activity, and at least 25 m of water-table lowering accompanied widespread erosion of older fine-grained deposits. Based on pack-rat midden and pollen evidence, this coincides with major vegetation changes in the valley, from sagebrush-dominated steppe to lower Mohave desertscrub.

The Occurrence of Certain Nonpasserine Birds in Southern Nevada

Since 1961 the author has spent considerable time in the field in Clark County, Nevada. The following records derived from this field work extend our knowledge of certain species which are considered uncommon to rare in southern Nevada. I am grateful to Charles G. Hansen, biologist, Desert Game Range, for access to his personal records and to the Desert Game Range Narrative Reports (DGRNR). All specimens are on deposit in the Biology Museum, Nevada Southern University. Porphyrula martinica. Purple Gallinule. Two individuals of this species were observed at Tule Springs Park, 13 miles northwest of downtown Las Vegas, in 1966. Single birds were observed there on 7, 8, and 20 September and a male (B-668, weight 183.2 g, left testis 8 x 2 mm, no fat) was collected on 8 September 1966. This constitutes the first record for Nevada. Charadrius semipalmatus. Semipalmated Plover. Spring records of this species for Henderson Slough, one mile north of Henderson, on 26 April 1967 (5 birds) and Tule Springs on 12 and 15 May 1967 (1 bird) supplement those of Grater (Condor 41:221, 1939) and Hayward et al. (Brigham Young Univ. Sci. Bull., Biol. Series 3:8, 1963). Fall records for Henderson Slough on 16 August (2 birds), 23 August (1 bird), and 2 September 1966 (2 birds), and for 1.5 miles west of Logandale on 13 September 1966 (10 birds) appear to be the first for this season in southern Nevada. Specimens were taken on 16 August (B-626, female, ovary 5 x 3 mm, weight 47.8 g, heavy fat), 23 August (B-655, female, ovary minute, 42.4 g, heavy fat), and 2 September (B-743, female, ovary 7 x 1.5 mm, 39.2 g, moderate fat). Charadrius alexandrinus. Snowy Plover. This species is an uncommon transient in Nevada. I have records of single birds of Henderson Slough on 16 and 23 August 1966. A female (B-627, ovary 5 x 3 mm, 31.2 g, light fat) was collected on 16 August. These appear to be the first fall records for southern Nevada. Arenaria interpres. Ruddy Turnstone. Alcorn (Condor 44:81, 1942) lists the single previous Nevada record of this species. A male (B-665, left testis 3 x 0.5 mm, 74.4 g, light fat) was collected 1.5 miles west of Logandale on 13 September 1966. Erolia bairdi. Baird's Sandpiper. Hayward et al. (op. cit., p. 9) give the only previous report of this species for southern Nevada. There is an unpublished record for Corn Creek on 22 April 1946 (DGRNR, January-April 1946). I have additional records for three birds 1.5 miles west of Logandale on 13 September 1966 (female collected, B-666, ovary 3 x 3 mm, 32.3 g, light fat) and for one at Tule Springs Park on 2 May 1967. Crocethia alba. Sanderling. The Sanderling has not been reported previously for southern Nevada. I saw a single bird at Tule Springs Park, 1-3 May 1966.

Geological and Geochemical Evidence Concerning the Antiquity of Bone Tools from Tule Springs, Site 2, Clark County, Nevada

AbstractTwo bone objects from the Tule Springs site, possibly tools, occurred in ancient sedimentary fill of a small spring outlet-channel remnant. The ancient spring was active more than 40,000 years ago and again 12,000 to 13,000 years ago. The fill and the bone contained therein could be of either age. Chemical and X-ray analysis on bone of the known ages and bone from the fill showed no significant or systematic differences in fluorine, uranium, nitrogen, or phosphate content. On geological grounds, it is concluded that the bone objects are 12,000 to 13,000 years old.

Tule Springs, Nevada, with other Evidences of Pleistocene Man in Nortfi America, Mark R. Harrington and Ruth DeEtte Simpson. Southwest Museum Papers, No. 18, Los Angeles, 1961. 146 pp., 60 figs., 6 charts, 3 maps. $3.75.

Tule Springs, Nevada, with other Evidences of Pleistocene Man in Nortfi America, Mark R. Harrington and Ruth DeEtte Simpson. Southwest Museum Papers, No. 18, Los Angeles, 1961. 146 pp., 60 figs., 6 charts, 3 maps. $3.75. - Volume 28 Issue 1