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Kyle House

Publications and source records attributed to Kyle House.

24 records · Page 2Linked to original sources
USGS2015

River-evolution and tectonic implications of a major Pliocene aggradation on the lower Colorado River: The Bullhead Alluvium

The ∼200-m-thick riverlaid Bullhead Alluvium along the lower Colorado River downstream of Grand Canyon records massive early Pliocene sediment aggradation following the integration of the upper and lower Colorado River basins. The distribution and extent of the aggraded sediments record (1) evolving longitudinal profiles of the river valley with implications for changing positions of the river’s mouth and delta; (2) a pulse of rapid early drainage-basin erosion and sediment supply; and (3) constraints on regional and local deformation. The Bullhead Alluvium is inset into the Hualapai and Bouse Formations along a basal erosional unconformity. Its base defines a longitudinal profile interpreted as the incised end result after the Colorado River integrated through lake basins. Subsequent Bullhead aggradation, at ca. 4.5–3.5 Ma, built up braid plains as wide as 50 km as it raised the Colorado River’s grade. We interpret the aggradation to record a spike in sediment supply when river integration and base-level fall destabilized and eroded relict landscapes and Tertiary bedrock in the Colorado River’s huge catchment. Longitudinal profiles of the Bullhead Alluvium suggest ≥200 m post-Bullhead relative fault uplifts in the upper Lake Mead area, >100 m local subsidence in the Blythe Basin, and deeper subsidence of correlative deltaic sequences in the Salton Trough along the Pacific–North American plate boundary. However, regionally, for >500 km along the river corridor from Yuma, Arizona, to Lake Mead, Arizona and Nevada, the top of the Bullhead Alluvium appears to be neither uplifted nor tilted, sloping 0.5–0.6 m/km downstream like the gradient of a smaller late Pleistocene aggradation sequence. Perched outcrops tentatively assigned to the Bullhead Alluvium near the San Andreas fault system project toward a Pliocene seashore or bayline twice as distant (300–450 km) as either the modern river’s mouth or a tectonically restored 4.25 Ma paleoshore. We conclude that Bullhead aggradation peaked after 4.25 Ma, having lengthened the delta plain seaward by outpacing both 2 mm/yr delta subsidence and 43–45 mm/yr transform-fault offset of the delta. Post-Bullhead degradation started before 3.3 Ma and implies that the river profile lowered and shortened because sediment supply declined, and progradation was unable to keep up with subsidence and plate motion in the delta.

Arizona, California, Nevada↗
USGS2014

Paleogeomorphology of the early Colorado River inferred from relationships in Mohave and Cottonwood Valleys, Arizona, California and Nevada

Geologic investigations of late Miocene–early Pliocene deposits in Mohave and Cottonwood valleys provide important insights into the early evolution of the lower Colorado River system. In the latest Miocene these valleys were separate depocenters; the floor of Cottonwood Valley was ∼200 m higher than the floor of Mohave Valley. When Colorado River water arrived from the north after 5.6 Ma, a shallow lake in Cottonwood Valley spilled into Mohave Valley, and the river then filled both valleys to ∼560 m above sea level (asl) and overtopped the bedrock divide at the southern end of Mohave Valley. Sediment-starved water spilling to the south gradually eroded the outlet as siliciclastic Bouse deposits filled the lake upstream. When sediment accumulation reached the elevation of the lowering outlet, continued erosion of the outlet resulted in recycling of stored lacustrine sediment into downstream basins; depth of erosion of the outlet and upstream basins was limited by the water levels in downstream basins. The water level in the southern Bouse basin was ∼300 m asl (modern elevation) at 4.8 Ma. It must have drained and been eroded to a level <150 m asl soon after that to allow for deep erosion of bedrock divides and basins upstream, leading to removal of large volumes of Bouse sediment prior to massive early Pliocene Colorado River aggradation. Abrupt lowering of regional base level due to spilling of a southern Bouse lake to the Gulf of California could have driven observed upstream river incision without uplift. Rapid uplift of the entire region immediately after 4.8 Ma would have been required to drive upstream incision if the southern Bouse was an estuary.

Arizona, California, Nevada↗
USGS2013

Overcoming the momentum of anachronism: American geologic mapping in a twenty-first-century world

The practice of geologic mapping is undergoing conceptual and methodological transformation. Profound changes in digital technology in the past 10 yr have potential to impact all aspects of geologic mapping. The future of geologic mapping as a relevant scientific enterprise depends on widespread adoption of new technology and ideas about the collection, meaning, and utility of geologic map data. It is critical that the geologic community redefine the primary elements of the traditional paper geologic map and improve the integration of the practice of making maps in the field and office with the new ways to record, manage, share, and visualize their underlying data. A modern digital geologic mapping model will enhance scientific discovery, meet elevated expectations of modern geologic map users, and accommodate inevitable future changes in technology.

GSA Special Papers↗
USGS2012

Introduction: CRevolution 2: origin and evolution of the Colorado River System II

A 2010 Colorado River symposium held in Flagstaff, Arizona, in May 2010, had 70 participants who engaged in intense debate about the origin and evolution of the Colorado River system. This symposium, built on two previous decadal scientific meetings, focused on forging scientific consensus where possible, while also articulating continued controversies regarding the Cenozoic evolution of the Colorado River System and the landscapes of the Colorado Plateau–Rocky Mountain region that it drains. New developments involved hypotheses that Neogene mantle flow is driving plateau tilting and differential uplift, with consensus that multidisciplinary studies involving differential incision studies and additional geochronology and thermochronology are needed to test the relative importance of tectonic and geomorphic forcings in shaping the spectacular landscapes of the Colorado Plateau region. In addition to the scientific goals, the meeting participants emphasized the iconic status of Grand Canyon for geosciences, and the importance of good communication between the research community, the geoscience education/interpretation community, the public, and the media. Building on a century-long tradition, this region still provides a globally important natural laboratory for studies of the interactions of erosion and tectonism in the shaping landscape of elevated plateaus.

Arizona;Colorado;New Mexico;Utah↗
USGS2005

Birth of the lower Colorado River–Stratigraphic and geomorphic evidence for its inception near the conjunction of Nevada, Arizona, and California

A detailed record of the late Cenozoic history of the lower Colorado River can be inferred from alluvial and (likely) lacustrine stratigraphy exposed in dissected alluvial basins below the mouth of the Grand Canyon. Numerous sites in Mohave, Cottonwood, and Detrital valleys contain stratigraphic records that directly bear on the mode, timing, and consequences of the river’s inception and integration in the latest Miocene–early Pliocene and its subsequent evolution through the Pleistocene. This field trip guide describes and illustrates many of these key stratigraphic relationships and, in particular, highlights evidence that supports the hypothesis of cascading lake-overflow as the principal formative mechanism of the river’s course downstream from the Grand Canyon.

Arizona, California, Nevada↗