This is a comprehensive scientific investigation of the geologic history and framework of the lower Colorado River. We are using geologic mapping in combination with stratigraphic, geochronologic, and geophysical studies to develop a holistic understanding of the river’s origin, the structural history of the landscape through which it flows, and the stratigraphic and geomorphic consequences of the river’s changes in response to long and short-term changes in regional tectonics and climate.
Science Issue and Relevance:
The lower Colorado River study area includes one of the world’s most iconic landscapes (Grand Canyon) and embodies a water resource that is essential to the water and electric power requirements of more than 40 Million people in the southwestern United States.
- There is wide-reaching cultural relevance in simply explaining the Grand Canyon, and we can’t begin to do that without understanding how the lower river corridor evolved.
- Regional crustal extension and associated sedimentary deposits created the characteristics of modern-day aquifers
- Detailed geologic mapping investigations build knowledge and provide deep insights into geologic processes and related natural hazards endemic to the lower Colorado River.
- Maps of the lower Colorado River will be integrated into National geologic map datasets.
Methodology to Address Issue:
Geologic mapping is the foundational method employed in this project. Mapping is a means of documenting, synthesizing and portraying scientific observations and interpretations of geologic deposits that record important episodes and timing of geologic activity. Our project is based primarily on surficial geologic mapping and regional-scale geologic maps but, will also conduct bedrock mapping and related structural studies. Our workflow involves characterizing and portraying a complex stratigraphic record at intermediate scale (e.g., 1:100,000). This process includes new geologic mapping in addition to compilation and refinement of existing maps, using a common stratigraphic nomenclature. These efforts are rely on modern GIS technology.
Geochronologic studies will focus on the ages of key Colorado River strata and underlying bedrock units and geologic structures that have influenced the river’s evolution. Structural and stratigraphic analysis of the geologic framework of the basins that hold voluminous water resources will be critically important in coming years and decades.
Below are other science projects associated with this project.
Luminescence Dating Laboratory
Argon Geochronology Laboratory
Denver Radiogenic Isotope Lab
Western Basin & Range - Eastern California Shear Zone
USGS Tephrochronology (Tephra) Project
Digital database for the geologic map of the Vidal, California, and Parker SW, California-Arizona quadrangles
Digital database for the geologic map of the Parker NW, Parker, and parts of the Whipple Mountains SW and Whipple Wash quadrangles, California and Arizona
Digital data documenting the evolution of Miocene normal and dextral faulting in the lower Colorado River region near Blythe, California, USA
Aeromagnetic Data and horizontal gradient maxima of Blythe, California, and Surrounding Areas in California and Arizona
Digital database of geologic units, contacts, and faults for Mineral Resource Potential Map of the Turtle Mountains Wilderness Study Area, San Bernardino County, California (U.S. Geological Survey Bulletin 1713-B, 1988, Plate 1)
Digital Data for the Preliminary Bedrock Geologic Map of the Blythe 30' x 60' Quadrangle, California and Arizona
Surficial geologic map of the Spirit Mountain SE and part of the Spirit Mountain NE 7.5' quadrangles, Nevada and Arizona
Geologic map of the Blythe 7.5' quadrangle, La Paz County, Arizona and Riverside County, California
Below are publications associated with this project.
Magmatic record of changing Cordilleran plate-boundary conditions—Insights from Lu-Hf isotopes in the Mojave Desert
Late Cretaceous time-transgressive onset of Laramide arch exhumation and basin subsidence across northern Arizona−New Mexico, USA, and the role of a dehydrating Farallon flat slab
Fault-influenced incision in western Grand Canyon, Arizona U.S.A.
Preliminary bedrock geologic map of the Blythe 30' x 60' quadrangle, California and Arizona
Testing models of Laramide orogenic initiation by investigation of Late Cretaceous magmatic-tectonic evolution of the central Mojave sector of the California arc
Redefining the age of the lower Colorado River, southwestern United States: Reply
Tectonostratigraphic record of late Miocene–early Pliocene transtensional faulting in the Eastern California shear zone, southwestern USA
Tectonostratigraphic record of late Miocene–early Pliocene transtensional faulting in the Eastern California shear zone, southwestern USA
Redefining the age of the lower Colorado River, southwestern United States
Oases: Finding hidden biodiversity gems in the southern Sonoran Desert
Post-12 Ma deformation of the lower Colorado River corridor, southwestern USA: Implications for diffuse transtension and the Bouse Formation
The Bouse Formation: A controversial Neogene archive of the evolving Colorado River: A scientific drilling workshop report (Feb. 28-March 3, 2019-Bluewater Resort, Parker, Arizona, USA
Below are partners associated with this project.
- Overview
This is a comprehensive scientific investigation of the geologic history and framework of the lower Colorado River. We are using geologic mapping in combination with stratigraphic, geochronologic, and geophysical studies to develop a holistic understanding of the river’s origin, the structural history of the landscape through which it flows, and the stratigraphic and geomorphic consequences of the river’s changes in response to long and short-term changes in regional tectonics and climate.
Deformed sediment of the Bouse Formation in Chemehuevi Valley, California. Complex deformation is a likely consequence of subaqueous mass wasting of part of a growing delta of the Colorado River. Science Issue and Relevance:
The lower Colorado River study area includes one of the world’s most iconic landscapes (Grand Canyon) and embodies a water resource that is essential to the water and electric power requirements of more than 40 Million people in the southwestern United States.
- There is wide-reaching cultural relevance in simply explaining the Grand Canyon, and we can’t begin to do that without understanding how the lower river corridor evolved.
- Regional crustal extension and associated sedimentary deposits created the characteristics of modern-day aquifers
- Detailed geologic mapping investigations build knowledge and provide deep insights into geologic processes and related natural hazards endemic to the lower Colorado River.
- Maps of the lower Colorado River will be integrated into National geologic map datasets.
Methodology to Address Issue:
Geologic mapping is the foundational method employed in this project. Mapping is a means of documenting, synthesizing and portraying scientific observations and interpretations of geologic deposits that record important episodes and timing of geologic activity. Our project is based primarily on surficial geologic mapping and regional-scale geologic maps but, will also conduct bedrock mapping and related structural studies. Our workflow involves characterizing and portraying a complex stratigraphic record at intermediate scale (e.g., 1:100,000). This process includes new geologic mapping in addition to compilation and refinement of existing maps, using a common stratigraphic nomenclature. These efforts are rely on modern GIS technology.
Linear tracts and small patches of well rounded and varnished pebbles and cobbles mark the traces of ancient channels, bars, and floodplain terraces of the lower Colorado River. Extremely long durations of exposure to the desert environment transform the surfaces of these deposits to flat, and tightly packed pavements of spectacularly discolored and varnished river rocks. Geochronologic studies will focus on the ages of key Colorado River strata and underlying bedrock units and geologic structures that have influenced the river’s evolution. Structural and stratigraphic analysis of the geologic framework of the basins that hold voluminous water resources will be critically important in coming years and decades.
Summer flash-floods can introduce large amounts, of fine reddish-orange sediment to the Colorado River with spectacular results - Science
Below are other science projects associated with this project.
Luminescence Dating LaboratoryLuminescence Dating LaboratoryArgon Geochronology LaboratoryArgon Geochronology LaboratoryDenver Radiogenic Isotope LabDenver Radiogenic Isotope LabWestern Basin & Range - Eastern California Shear Zone
The Eastern California Shear Zone (ECSZ) Mapping project, funded by the National Cooperative Geologic Mapping Program, combines surficial and bedrock geologic mapping, geophysical surveys, and high-resolution topographic data analysis with neotectonic, geomorphic, structural, volcanic, and geochronologic studies to better understand the tectonic framework and landscape evolution of the ECSZ in the...USGS Tephrochronology (Tephra) Project
Tephrochronology is the study of volcanic ash deposits, combining petrology, geochemistry, and isotopic dating methods. We use tephrochronology, along with other chronostratigraphic techniques, to (1) determine the ages of coincident deposits, and, when multiple tephra layers are present, determine the history of geologic events and rates of geologic processes; and (2) correlate sediments from... - Data
Digital database for the geologic map of the Vidal, California, and Parker SW, California-Arizona quadrangles
This geologic database is a digitized version of the original 1:24,000-scale analog geologic map titled "Geologic map of the Vidal, California, and Parker SW, California-Arizona quadrangles", published by the U.S. Geological Survey (USGS) in 1980. The map area straddles the Arizona-California border, and is located approximately 9.0 km (5.6 mi) west-southwest of Parker, CA, immediately south of thDigital database for the geologic map of the Parker NW, Parker, and parts of the Whipple Mountains SW and Whipple Wash quadrangles, California and Arizona
This geologic database is a digitized version of the 1:24,000-scale original analog geologic map titled "Geologic map of the Parker NW, Parker, and parts of the Whipple Mountains SW and Whipple Wash quadrangles, California and Arizona", published by the U.S. Geological Survey (USGS) in 1980. The map area straddles the Arizona-California border and includes the community of Parker, AZ, and the soutDigital data documenting the evolution of Miocene normal and dextral faulting in the lower Colorado River region near Blythe, California, USA
These datasets provide the measurements and analytical data used to describe the evolution of Neogene faulting near Blythe, California. The data include structural measurements and results from Ar-Ar and U-Pb geochronology that address the research questions of the associated publication. Structural measurement datasets provide fault surface kinematic measurements and tabulations of structural datAeromagnetic Data and horizontal gradient maxima of Blythe, California, and Surrounding Areas in California and Arizona
This data release provides access to an aeromagnetic survey and magnetization boundaries over Blythe, California and surrounding areas in southern California and western Arizona. The survey extends east of Joshua Tree National Park across the Colorado River and west over the Dome Rock, Trigo, and Plomosa Mountains in Arizona. The survey was flown north of the Chocolate Mountains Gunnery Range overDigital database of geologic units, contacts, and faults for Mineral Resource Potential Map of the Turtle Mountains Wilderness Study Area, San Bernardino County, California (U.S. Geological Survey Bulletin 1713-B, 1988, Plate 1)
This map geodatabase digitally represents the general distribution of bedrock geologic map units in the Turtle Mountains area, California, as portrayed in Plate 1 of USGS Bulletin 1713-B, Mineral resources of the Turtle Mountains Wilderness Study Area, San Bernardino County, California (1988), https://doi.org/10.3133/b1713B. The map covers parts of the Rice, Turtle Mountains, and Savahia Peak 15’Digital Data for the Preliminary Bedrock Geologic Map of the Blythe 30' x 60' Quadrangle, California and Arizona
This Geologic Map Schema (GeMS) database contains all the geologic map information used to publish the Preliminary Bedrock Geologic Map of the Blythe 30' x 60' Quadrangle, California and Arizona, U.S. Geological Survey Open-File Report 2021-1097. The Blythe 30' x 60' quadrangle in southeastern California and southwestern Arizona displays complex geology that includes Mesozoic contractional deforma - Maps
Surficial geologic map of the Spirit Mountain SE and part of the Spirit Mountain NE 7.5' quadrangles, Nevada and Arizona
This geologic map includes a trove of stratigraphic and geomorphic information that chronicles the inception and evolution of the lower Colorado River. The map area is located near the south end of the Lake Mead National Recreation Area about 80 km (50 mi) downstream from Hoover Dam. It spans parts of northwestern Arizona and southern Nevada near the south end of Cottonwood Valley. The map includeGeologic map of the Blythe 7.5' quadrangle, La Paz County, Arizona and Riverside County, California
The geologic map of the Blythe 7.5' quadrangle spans about 60 percent of the width of the Holocene floodplain and valley floor of the lower Colorado River and the adjacent lower piedmont on the east side of the Colorado River Valley. This map depicts a composite geologic record of the river’s response to the transition from a natural flow regime to a strictly regulated one created by a series of u - Publications
Below are publications associated with this project.
Filter Total Items: 18Magmatic record of changing Cordilleran plate-boundary conditions—Insights from Lu-Hf isotopes in the Mojave Desert
Belts of Cordilleran arc plutons in the eastern part of the Mojave crustal province, inboard from the southwestern North American plate boundary, record major magmatic pulses at ca. 180–160 and 75 Ma and smaller pulses at ca. 100 and 20 Ma. This cyclic magmatism likely reflects evolving plate-margin processes. Zircon Lu-Hf isotopic characteristics and inherited zircons for different-age plutons maAuthorsKeith A. Howard, S.E. Shaw, Charlotte M. AllenLate Cretaceous time-transgressive onset of Laramide arch exhumation and basin subsidence across northern Arizona−New Mexico, USA, and the role of a dehydrating Farallon flat slab
Spatiotemporal constraints for Late Cretaceous tectonism across the Colorado Plateau and southern Rocky Mountains (northern Arizona−New Mexico, USA) are interpreted in regards to Laramide orogenic mechanisms. Onset of Laramide arch development is estimated from cooling recorded in representative thermochronologic samples in a three-step process of initial forward models, secondary HeFTy inverse moAuthorsJacob Thacker, Karl Karlstrom, Shari Kelley, Ryan S. Crow, Jerry KendallFault-influenced incision in western Grand Canyon, Arizona U.S.A.
Preliminary interpretation of new and updated incision rates in western Grand Canyon shows the effects of Quaternary faulting, which dampens river incision rates in the footwalls and amplifies them in the hanging walls of normal faults. In the reach between Lava Falls and Diamond Creek in western Grand Canyon, about 178 to 225 river miles downstream from Lees Ferry, the river crosses the neotectonAuthorsRyan S. Crow, Karl Karlstrom, Warren Sharp, Victor Polyak, Yemane Asmerom, Laura CrosseyPreliminary bedrock geologic map of the Blythe 30' x 60' quadrangle, California and Arizona
The Blythe 30' x 60' quadrangle in southeastern California and southwestern Arizona displays complex geology that includes Mesozoic contractional deformation, metamorphism, and magmatism in addition to Cenozoic extensional deformation and magmatism. Previous geologic map compilations predate recent geologic mapping efforts that have contributed new insights into the stratigraphy and structure of tTesting models of Laramide orogenic initiation by investigation of Late Cretaceous magmatic-tectonic evolution of the central Mojave sector of the California arc
The Mojave Desert region is in a critical position for assessing models of Laramide orogenesis, which is hypothesized to have initiated as one or more seamounts subducted beneath the Cretaceous continental margin. Geochronological and geochemical characteristics of Late Cretaceous magmatic products provide the opportunity to test the validity of Laramide orogenic models. Laramide-aged plutons areAuthorsR.C Economos, Andrew P. Barth, J.L. Wooden, S. R Paterson, Brody Friesenhahn, B.A Weigand, J.L. Anderson, J.L. Roell, E.F. Palmer, A.J. Ianno, Keith A. HowardRedefining the age of the lower Colorado River, southwestern United States: Reply
Crow et al. (2021) report new geochronologic and paleomagnetic data indicating that the lower Colorado River (CR) became integrated to the proto–Gulf of California (GOC) between 4.8 and 4.62 Ma instead of at ca. 5.3 Ma, as suggested by Dorsey et al. (2007, 2018). Dorsey et al. (2021) dispute this new chronology but offer no alternative explanation for one of the key data sets requiring it, new detAuthorsRyan S. Crow, Jonathan Schwing, Karl Karlstrom, Matt Heizler, Philip Pearthree, Kyle House, Shannon Dulin, Susane Janecke, Mark E. Stelten, Laurie CrosseyTectonostratigraphic record of late Miocene–early Pliocene transtensional faulting in the Eastern California shear zone, southwestern USA
The Eastern California shear zone (ECSZ; southwestern USA) accommodates ~20%–25% of Pacific–North America relative plate motion east of the San Andreas fault, yet little is known about its early tectonic evolution. This paper presents a detailed stratigraphic and structural analysis of the uppermost Miocene to lower Pliocene Bouse Formation in the southern Blythe Basin, lower Colorado River valleyAuthorsRebecca J. Dorsey, Brennan O'Connell, Kevin Gardner, Mindy B. Homan, Scott E. K. Bennett, Jacob Thacker, Michael H. DarinTectonostratigraphic record of late Miocene–early Pliocene transtensional faulting in the Eastern California shear zone, southwestern USA
The Eastern California shear zone (ECSZ; southwestern USA) accommodates ~20%–25% of Pacific–North America relative plate motion east of the San Andreas fault, yet little is known about its early tectonic evolution. This paper presents a detailed stratigraphic and structural analysis of the uppermost Miocene to lower Pliocene Bouse Formation in the southern Blythe Basin, lower Colorado River valleyAuthorsRebecca J. Dorsey, Brennan O'Connell, Kevin Gardner, Mindy B. Homan, Scott E. K. Bennett, Jacob Thacker, Michael H. DarinRedefining the age of the lower Colorado River, southwestern United States
Sanidine dating and magnetostratigraphy constrain the timing of integration of the lower Colorado River (southwestern United States and northern Mexico) with the evolving Gulf of California. The Colorado River arrived at Cottonwood Valley (Nevada and Arizona) after 5.24 Ma (during or after the Thvera subchron). The river reached the proto–Gulf of California once between 4.80 and 4.63 Ma (during thAuthorsRyan S. Crow, J. Schwing, K. E. Karlstrom, M. Heizler, P. A. Pearthree, P. K. House, S. Dulin, S. U. Janecke, Mark E. Stelten, L. J. CrosseyOases: Finding hidden biodiversity gems in the southern Sonoran Desert
In the arid southern Sonoran Desert, the rugged canyons of the Sierra El Aguaje contain numerous freshwater oases. These habitats are supported by small springs which are usually located along geologic faults in volcanic and granitic bedrock. Genetic evidence from freshwater-obligate species (e.g., fish and frogs) suggests these or similar spring-fed habitats have persisted for thousands to millioAuthorsMichael T. Bogan, Carlos Ballesteros-Córdova, S. Bennett, Michael H. Darin, Lloyd T. Findley, Alejandro Varela-RomeroPost-12 Ma deformation of the lower Colorado River corridor, southwestern USA: Implications for diffuse transtension and the Bouse Formation
Structural evidence presented here documents that deformation was ongoing within the lower Colorado River corridor (southwestern USA) during and after the latest Miocene Epoch, postdating large-magnitude extension and metamorphic core complex formation. Geometric and kinematic data collected on faults in key geologic units constrain the timing of deformation in relation to the age of the Bouse ForAuthorsJacob Thacker, Karl Karlstrom, Laura Crossey, Ryan S. Crow, Colleen Cassidy, L. Sue Beard, John Singleton, Evan Strickland, Nikki Seymour, Michael WyattThe Bouse Formation: A controversial Neogene archive of the evolving Colorado River: A scientific drilling workshop report (Feb. 28-March 3, 2019-Bluewater Resort, Parker, Arizona, USA
Neogene deposits of the lower Colorado River valley, especially the Miocene(?) and early Pliocene Bouse Formation, have been the focus of intense debate regarding the early paleoenvironmental history of this important continental-scale river system in southwestern North America and its integration with the proto-Gulf of California. Fine-grained units within these Neogene deposits also hold a promiAuthorsAndrew S. Cohen, Colleen Cassidy, Ryan S. Crow, Jordon Bright, Laura Crossey, Rebecca Dorsey, Brian F. Gootee, Kyle House, Keith A. Howard, Karl Karlstrom, Philip Pearthree - Partners
Below are partners associated with this project.