This dataset includes tables of U- and Th-isotopic data used to calculate uranium-series age estimates (230Th/U method) and initial 234U/238U activity ratios for samples of pedogenic carbonate formed in soils on alluvial fans in the San Luis Valley, Colorado, USA.

This dataset includes tables with physical information and isotopic data that are used to calculate uranium-series ages (230Th/U method) and initial 234U/238U activity ratios on a suite of mastodon bones from the Cerutti Mastodon site near San Diego, CA area.

In conjunction with geologic mapping of four 7.5′ quadrangles along the South Platte River corridor in northeastern Colorado (Masters, Orchard, Weldona, and Fort Morgan), geochronology samples were collected and analyzed using optically stimulated luminescence (OSL), radiocarbon (14C), or U-series methods to provide age control for mapping units. This section of river corridor is largely covered by surficial deposits that formed from alluvial, eolian, and hillslope processes operating in concert with environmental changes from the Pleistocene to the present. The South Platte River originates high in the Colorado Rocky Mountains and recurrent glaciation of basin headwaters has affected river discharge and sediment supply far downstream, influencing aggradation and incision along this part of the river corridor. Unglaciated tributaries originating in the Colorado Piedmont east of the Front Range have periodically deposited large volumes of sediment at their confluences during major flood events. Eolian sand deposits cover much of the area and record past episodes of sand mobilization during times of prolonged drought. Sediment samples dated using OSL provide ages for alluvial and eolian sand deposits; organic samples dated using 14C methods constrain ages of alluvial deposits; and bone and river gravels with calcium carbonate rinds dated using U-series methods provide minimum ages for alluvial deposits.

In conjunction with geologic mapping of four 7.5′ quadrangles along the South Platte River corridor in northeastern Colorado (Masters, Orchard, Weldona, and Fort Morgan), geochronology samples were collected and analyzed using optically stimulated luminescence (OSL), radiocarbon (14C), or U-series methods to provide age control for mapping units. This section of river corridor is largely covered by surficial deposits that formed from alluvial, eolian, and hillslope processes operating in concert with environmental changes from the Pleistocene to the present. The South Platte River originates high in the Colorado Rocky Mountains and recurrent glaciation of basin headwaters has affected river discharge and sediment supply far downstream, influencing aggradation and incision along this part of the river corridor. Unglaciated tributaries originating in the Colorado Piedmont east of the Front Range have periodically deposited large volumes of sediment at their confluences during major flood events. Eolian sand deposits cover much of the area and record past episodes of sand mobilization during times of prolonged drought. Sediment samples dated using OSL provide ages for alluvial and eolian sand deposits; organic samples dated using 14C methods constrain ages of alluvial deposits; and bone and river gravels with calcium carbonate rinds dated using U-series methods provide minimum ages for alluvial deposits.

The following report summarizes the dating results from the San Luis Valley-Pioneer Fan 2017-2019 dating project. Within this report, we detail the methodology used by the USGS Luminescence Geochronology Laboratory to obtain ages including sample preparation methods, luminescence measurement, equivalent dose determination, and dating-related calculations. We recommend that this report be included as the supplementary material for any publication(s) that use the ages within this report.

This data release contains three comma separated value (.csv) tables describing data from alluvial cobbles collected from a Pleistocene alluvial deposit on the noerth side of Poncha Pass, near Salida, Colorado. Tables "DryUnion_Burial_Isochron_Aluminum26_Cyr.csv" and "DryUnion_Burial_Isochron_Beryllium10_Cyr.csv" contain aluminum-26 and beryllium-10 data, respectively, for samples collected in Poncha Pass, Colorado on July 15, 2015. Table "DryUnion_LocationAndIsochronBurialAge_Cyr.csv" contains location, elevation, site-specific nuclide production ratios, and interpreted isochron burial age results. Physical and chemical isolation of clean quartz was carried out in the Menlo Park Cosmogenic Nuclide Lab; chemical isolation of aluminum and beryllium, and isotope analysis by accelerator mass spectrometry, were completed at the Purdue Rare Isotope Measurement (PRIME) Lab at Purdue University, West Lafayette, Indiana. Users of this dataset should note that "Dry Union" was used as a geographic designation at the time of sample collection. Subsequent geologic mapping has demonstrated that both the "Upper Dry Union" and "Lower Dry Union" sets of samples were collected from an alluvial apron, unit Qoa of Minor and others (2019), that laps unconformably on the Dry Union Formation (as defined by Minor and others, 2019 and references therein). Our isochron burial age result demonstrates that unit Qoa at this location is 0.30 +/- 0.05 Ma.

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 the unincorporated communities of Vidal and Vidal Junction, CA. The map area includes the northern Riverside Mountains, which contain a prominent suite of Permian, Mesozoic, and potentially Precambrian metamorphic and metasedimentary rocks. These rocks predominantly consist of gneisses, schists, limestones, and dolomites, separated by three mapped structural discontinuities and the prominent Whipple Mountains Detachment Fault. The map area additionally contains small outcrops of Miocene intermediate-to-felsic volcanic rocks consisting of basaltic andesite flows, andesitic porphyry, rhyolitic intrusives, and the Peach Springs Tuff. The Riverside Mountains are surrounded by numerous sedimentary units, largely consisting of fluvial deposits, that record the arrival and subsequent fluctuations of the Colorado River in the region from the Pliocene through the Holocene. These sedimentary units additionally record Quaternary alluvial fan processes on the flanks of the Riverside Mountains and in the lower Vidal Valley.

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 the unincorporated communities of Vidal and Vidal Junction, CA. The map area includes the northern Riverside Mountains, which contain a prominent suite of Permian, Mesozoic, and potentially Precambrian metamorphic and metasedimentary rocks. These rocks predominantly consist of gneisses, schists, limestones, and dolomites, separated by three mapped structural discontinuities and the prominent Whipple Mountains Detachment Fault. The map area additionally contains small outcrops of Miocene intermediate-to-felsic volcanic rocks consisting of basaltic andesite flows, andesitic porphyry, rhyolitic intrusives, and the Peach Springs Tuff. The Riverside Mountains are surrounded by numerous sedimentary units, largely consisting of fluvial deposits, that record the arrival and subsequent fluctuations of the Colorado River in the region from the Pliocene through the Holocene. These sedimentary units additionally record Quaternary alluvial fan processes on the flanks of the Riverside Mountains and in the lower Vidal Valley.

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 the unincorporated communities of Vidal and Vidal Junction, CA. The map area includes the northern Riverside Mountains, which contain a prominent suite of Permian, Mesozoic, and potentially Precambrian metamorphic and metasedimentary rocks. These rocks predominantly consist of gneisses, schists, limestones, and dolomites, separated by three mapped structural discontinuities and the prominent Whipple Mountains Detachment Fault. The map area additionally contains small outcrops of Miocene intermediate-to-felsic volcanic rocks consisting of basaltic andesite flows, andesitic porphyry, rhyolitic intrusives, and the Peach Springs Tuff. The Riverside Mountains are surrounded by numerous sedimentary units, largely consisting of fluvial deposits, that record the arrival and subsequent fluctuations of the Colorado River in the region from the Pliocene through the Holocene. These sedimentary units additionally record Quaternary alluvial fan processes on the flanks of the Riverside Mountains and in the lower Vidal Valley.