Richard Hereford | U.S. Geological Survey (original) (raw)

Papers by Richard Hereford

Research paper thumbnail of Reevaluation of the Crooked Ridge River—Early Pleistocene (ca. 2 Ma) age and origin of the White Mesa alluvium, northeastern Arizona

Research paper thumbnail of Sediment yield and runoff frequency of small drainage basins in the Mojave Desert, California and Nevada

Fact Sheet, 2006

Sediment yield from small arid basins, particularly in the Mojave Desert, is largely unknown owin... more Sediment yield from small arid basins, particularly in the Mojave Desert, is largely unknown owing to the ephemeral nature of these fluvial systems and long recurrence interval of flow events. We examined 27 reservoirs in the northern and eastern Mojave Desert that trapped sediment from small (b1 km 2 ) drainage basins on alluvial fans over the past 100 yr, calculated annual sediment yield, and estimated the average recurrence interval (RI) of sediment-depositing flow events. These reservoirs formed where railbeds crossed and blocked channels, causing sediment to be trapped and stored upslope. Deposits are temporally constrained by the date of railway construction (1906)(1907)(1908)(1909)(1910), the presence of 137 Cs in the reservoir profile (post-1952 sediment), and either 1993, when some basins breached during regional flooding, or 2000-2001, when stratigraphic analyses were performed. Reservoir deposits are well stratified at most sites and have distinct fining-upward couplets indicative of discrete episodes of sediment-bearing runoff. Average RI of runoff events for these basins ranges from 2.6 to 7.3 yr and reflects the incidence of either intense or prolonged rainfall; more than half the runoff events occurred before 1963. A period of above-normal precipitation, from 1905 to 1941, may have increased runoff frequency in these basins. Mean sediment yield (9 to 48 tons km À 2 yr À 1 ) is an order of magnitude smaller than sediment yields calculated elsewhere and may be limited by reduced storm intensity, the presence of desert pavement, and shallow gradient of fan surfaces. Sediment yield decreases as drainage area increases, a trend typical of much larger drainage basins where sediment-transport processes constrain sediment yield. Coarse substrate and low-angle slopes of these alluvial fan surfaces likely limit sediment transport capacity through transmission losses and channel storage. D

Research paper thumbnail of Map showing Quarternary geology and geomorphology of the Lonely Dell reach of the Paria River, Lees Ferry, Arizona

Research paper thumbnail of Geomorphic and hydrologic control of sediment and salt loads in the Colorado River basin; significance for conservation and land management

Research paper thumbnail of Precipitation history of the Colorado Plateau region, 1900-2000

Fact Sheet, 2002

... Figure 3. Standardized anomaly index (SAI) of seasonal precipitation for the Colorado Plateau... more ... Figure 3. Standardized anomaly index (SAI) of seasonal precipitation for the Colorado Plateau. Blue lines are cool seasons and red lines are warm seasons. Solid circles are the 10 wettest and driest seasons for the period 1900–2000. ...

Research paper thumbnail of Historical arroyo formation: Documentation of magnitude and timing of historical changes using repeat photography

... ila River Sa lt R iv er Verde River Santa Cruz River Little Colorado River San Juan River G .... more ... ila River Sa lt R iv er Verde River Santa Cruz River Little Colorado River San Juan River G ... Springs in the Santa Cruz River south of and at Martinez Hill (the camera station) prompted Spanish mission ... Bierman, PR, J. Howe, E. Stanley-Mann, M. Peabody, J. Hilke, and CA Massey ...

Research paper thumbnail of National Uranium Resource Evaluation: Flagstaff Quadrangle, Arizona

Five areas are believed to be favorable for the occurrence of uranium deposits in the Flagstaff 1... more Five areas are believed to be favorable for the occurrence of uranium deposits in the Flagstaff 1°x2° quadrangle. Areas favorable for uranium deposits in collapse breccia pipes are within the Coconino and Marble Plateaus and the Little River Valley. Three areas of Mesozoic sediments are deemed favorable for the occurrence of sandstone-type deposits. Uranium mineralization is present in lake-bed bearing

Research paper thumbnail of Geology, structure, and uranium deposits of the Flagstaff lºx2º quadrangle, Arizona

Research paper thumbnail of Precipitation variability of the Grand Canyon region, 1893 through 2009, and its implications for studying effects of gullying of Holocene terraces and associated archeological sites in Grand Canyon, Arizona

Research paper thumbnail of Late Holocene Alluvial Geomorphology of the Virgin River in the Zion National Park Area, Southwest Utah

Special Paper 310: Late Holocene alluvial geomorphology of the Virgin River in the Zion National Park area, Southwest Utah, 1996

... 3300 Penrose Place, PO Box 9140, Boulder, Colorado 80301 Printed in USA GSA Books Science Edi... more ... 3300 Penrose Place, PO Box 9140, Boulder, Colorado 80301 Printed in USA GSA Books Science Editor Abhijit Basu Library of Congress ... abundant gravel-size sediment from the ledge-forming Cretaceous-age sandstone in the headwaters of the basin (Sable and Hereford ...

Research paper thumbnail of Numerical Ages of Holocene Tributary Debris Fans Inferred from Dissolution Pitting on Carbonate Boulders in the Grand Canyon of Arizona

Quaternary Research, 1998

Colorado River in Grand Canyon National Park. Weakly acidic rainfall and the metabolic activity o... more Colorado River in Grand Canyon National Park. Weakly acidic rainfall and the metabolic activity of blue-green algae have produced roughly hemispheric dissolution pits as much as 2-cm deep on the initially smooth surfaces of the boulders. The average depth of dissolution pits increases with relative age of fan surfaces. The deepening rate averages 2.4 mm/1000 yr (standard error ‫؍‬ 0.2 mm/1000 yr), as calculated from several radiometrically dated surfaces and an archeological structure. This linear rate, which appears constant over at least the past 3000 yr, is consistent with field relations limiting the maximum age of the fans and with the physical chemistry of limestone dissolution. Dissolution-pit measurements (n ‫؍‬ 6973) were made on 617 boulders on 71 fan surfaces at the 26 largest debris fans in Grand Canyon. Among these fan surfaces, the average pit depth ranges from 1.2 to 17.4 mm, and the resulting pit dissolution ages range from 500 to 7300 cal yr B.P. Most (75%) surfaces are younger than 3000 yr, probably because of removal of older debris fans by the Colorado River. Many of the ages are close to 800, 1600, 2300, 3100, or 4300 cal yr B.P. If not the result of differential preservation of fan surfaces, this clustering implies periods of heightened debris-flow activity and increased precipitation. © 1998 University of Washington.

Research paper thumbnail of Channel evolution and hydrologic variations in the Colorado River basin: Factors influencing sediment and salt loads

Journal of Hydrology, 1991

Gellis, A., Hereford, R., Schumm, S.A. and Hayes, B.R., 1991. Channel evolution and hydrologic va... more Gellis, A., Hereford, R., Schumm, S.A. and Hayes, B.R., 1991. Channel evolution and hydrologic variations in the Colorado River basin: factors influencing sediment and salt loads. J. Hydrol., 124:317 344.

Research paper thumbnail of Precipitation history and ecosystem response to multidecadal precipitation variability in the Mojave Desert region, 1893–2001

Journal of Arid Environments, 2006

Precipitation varied substantially in the Mojave Desert through the 20th century in a manner broa... more Precipitation varied substantially in the Mojave Desert through the 20th century in a manner broadly similar to the other warm North American deserts. Episodes of drought and prolonged dry conditions (1893-1904, ca. 1942-1975, and 1999-present) alternated with relatively wet periods (1905-ca. 1941 and ca. 1976-1998), probably because of global-scale climate fluctuations. These are the El Nin˜o-Southern Oscillation that affects interannual climate and the Pacific Decadal Oscillation that evidently causes decadal-scale variability such as prolonged dry and wet episodes. Studies done in the late 20th century demonstrate that precipitation fluctuations affected populations of perennial vegetation, annuals, and small herbivores. Landscape rephotography reveals that several species, particularly creosote bush, increased in size and density during the ca. 1976-1998 wet period. A brief, intense drought from 1989 to 1991 and the ongoing drought caused widespread mortality of certain species; for example, chenopods and perennial grasses suffered up to 100% mortality. Drought pruning, the shedding of above-ground biomass to reduce carbon allocation, increased substantially during drought. Overall, drought had the greatest influence on the Mojave Desert ecosystem. r

Research paper thumbnail of Sediment yield and runoff frequency of small drainage basins in the Mojave Desert, U.S.A

Geomorphology, 2006

Sediment yield from small arid basins, particularly in the Mojave Desert, is largely unknown owin... more Sediment yield from small arid basins, particularly in the Mojave Desert, is largely unknown owing to the ephemeral nature of these fluvial systems and long recurrence interval of flow events. We examined 27 reservoirs in the northern and eastern Mojave Desert that trapped sediment from small (b1 km 2 ) drainage basins on alluvial fans over the past 100 yr, calculated annual sediment yield, and estimated the average recurrence interval (RI) of sediment-depositing flow events. These reservoirs formed where railbeds crossed and blocked channels, causing sediment to be trapped and stored upslope. Deposits are temporally constrained by the date of railway construction (1906)(1907)(1908)(1909)(1910), the presence of 137 Cs in the reservoir profile (post-1952 sediment), and either 1993, when some basins breached during regional flooding, or 2000-2001, when stratigraphic analyses were performed. Reservoir deposits are well stratified at most sites and have distinct fining-upward couplets indicative of discrete episodes of sediment-bearing runoff. Average RI of runoff events for these basins ranges from 2.6 to 7.3 yr and reflects the incidence of either intense or prolonged rainfall; more than half the runoff events occurred before 1963. A period of above-normal precipitation, from 1905 to 1941, may have increased runoff frequency in these basins. Mean sediment yield (9 to 48 tons km À 2 yr À 1 ) is an order of magnitude smaller than sediment yields calculated elsewhere and may be limited by reduced storm intensity, the presence of desert pavement, and shallow gradient of fan surfaces. Sediment yield decreases as drainage area increases, a trend typical of much larger drainage basins where sediment-transport processes constrain sediment yield. Coarse substrate and low-angle slopes of these alluvial fan surfaces likely limit sediment transport capacity through transmission losses and channel storage. D

Research paper thumbnail of Multiple constraints on the age of a Pleistocene lava dam across the Little Colorado River at Grand Falls, Arizona

Geological Society of America Bulletin, 2006

... about the growth of the field, including interpretation of the 100 m/my rate of regional down... more ... about the growth of the field, including interpretation of the 100 m/my rate of regional downcutting calculated from whole-rock K-Ar ages for samples from the two older lava dams along the Little Colorado River (Damon et al ... Corresponding author nancy.riggs{at}nau.edu. ...

Research paper thumbnail of Relation of sediment load and flood-plain formation to climatic variability, Paria River drainage basin, Utah and Arizona

Geological Society of America Bulletin, 1991

Research paper thumbnail of Historic variation of warm-season rainfall, Southern Colorado Plateau, Southwestern U.S.A

Climatic Change, 1992

Rainfall during the warm season (June 15-October 15) is the most important of the year in terms o... more Rainfall during the warm season (June 15-October 15) is the most important of the year in terms of flood generation and erosion in rivers of the southern Colorado Plateau. Fluvial erosion of the plateau decreased substantially in the 1930s to early 1940s, although the cause of this change has not been linked to variation of warm-season rainfall. This study shows that a decrease of warmseason rainfall frequency was coincident with and probably caused the decreased erosion by reducing the probability of large floods. Warm-season rainfall results from isolated thunderstorms associated with the Southwestern monsoon and from dissipating tropical cyclones and (or) cutoff low-pressure systems that produce widespread, general rainfall. Warm-season rainfall is typically normal to above normal during warm E1 Nifio-Southern Oscillation (ENSO) conditions. A network of 24 long-term precipitation gages was used to develop an index of standardized rainfall anomalies for the southern Colorado Plateau for the period 1900-85. The index shows that the occurrence of anomalously dry years increased and the occurrence of anomalously wet years decreased after the early 1930s, although 1939-41, 1972, and 1980-84 were anomalously wet. The decrease in warm-season rainfall after the early 1930s is related to a decrease in rainfall from dissipating tropical cyclones, shifts in the incidence of meridionat circulation in the upper atmosphere, and variability of ENSO conditions.

Research paper thumbnail of Tributary debris fans and the late Holocene alluvial chronology of the Colorado River, eastern Grand Canyon, Arizona

Geological Society of America Bulletin, 1996

... Select this article. B. Dubé,; GR Dunning,; K. Lauzière,; and JC Roddick. New insights into t... more ... Select this article. B. Dubé,; GR Dunning,; K. Lauzière,; and JC Roddick. New insights into the Appalachian Orogen from geology and geochronology along the Cape Ray fault zone, southwest Newfoundland. ... Select this article. William F. Outerbridge. ...

Research paper thumbnail of Reevaluation of the Crooked Ridge River—Early Pleistocene (ca. 2 Ma) age and origin of the White Mesa alluvium, northeastern Arizona

Research paper thumbnail of Sediment yield and runoff frequency of small drainage basins in the Mojave Desert, California and Nevada

Fact Sheet, 2006

Sediment yield from small arid basins, particularly in the Mojave Desert, is largely unknown owin... more Sediment yield from small arid basins, particularly in the Mojave Desert, is largely unknown owing to the ephemeral nature of these fluvial systems and long recurrence interval of flow events. We examined 27 reservoirs in the northern and eastern Mojave Desert that trapped sediment from small (b1 km 2 ) drainage basins on alluvial fans over the past 100 yr, calculated annual sediment yield, and estimated the average recurrence interval (RI) of sediment-depositing flow events. These reservoirs formed where railbeds crossed and blocked channels, causing sediment to be trapped and stored upslope. Deposits are temporally constrained by the date of railway construction (1906)(1907)(1908)(1909)(1910), the presence of 137 Cs in the reservoir profile (post-1952 sediment), and either 1993, when some basins breached during regional flooding, or 2000-2001, when stratigraphic analyses were performed. Reservoir deposits are well stratified at most sites and have distinct fining-upward couplets indicative of discrete episodes of sediment-bearing runoff. Average RI of runoff events for these basins ranges from 2.6 to 7.3 yr and reflects the incidence of either intense or prolonged rainfall; more than half the runoff events occurred before 1963. A period of above-normal precipitation, from 1905 to 1941, may have increased runoff frequency in these basins. Mean sediment yield (9 to 48 tons km À 2 yr À 1 ) is an order of magnitude smaller than sediment yields calculated elsewhere and may be limited by reduced storm intensity, the presence of desert pavement, and shallow gradient of fan surfaces. Sediment yield decreases as drainage area increases, a trend typical of much larger drainage basins where sediment-transport processes constrain sediment yield. Coarse substrate and low-angle slopes of these alluvial fan surfaces likely limit sediment transport capacity through transmission losses and channel storage. D

Research paper thumbnail of Map showing Quarternary geology and geomorphology of the Lonely Dell reach of the Paria River, Lees Ferry, Arizona

Research paper thumbnail of Geomorphic and hydrologic control of sediment and salt loads in the Colorado River basin; significance for conservation and land management

Research paper thumbnail of Precipitation history of the Colorado Plateau region, 1900-2000

Fact Sheet, 2002

... Figure 3. Standardized anomaly index (SAI) of seasonal precipitation for the Colorado Plateau... more ... Figure 3. Standardized anomaly index (SAI) of seasonal precipitation for the Colorado Plateau. Blue lines are cool seasons and red lines are warm seasons. Solid circles are the 10 wettest and driest seasons for the period 1900–2000. ...

Research paper thumbnail of Historical arroyo formation: Documentation of magnitude and timing of historical changes using repeat photography

... ila River Sa lt R iv er Verde River Santa Cruz River Little Colorado River San Juan River G .... more ... ila River Sa lt R iv er Verde River Santa Cruz River Little Colorado River San Juan River G ... Springs in the Santa Cruz River south of and at Martinez Hill (the camera station) prompted Spanish mission ... Bierman, PR, J. Howe, E. Stanley-Mann, M. Peabody, J. Hilke, and CA Massey ...

Research paper thumbnail of National Uranium Resource Evaluation: Flagstaff Quadrangle, Arizona

Five areas are believed to be favorable for the occurrence of uranium deposits in the Flagstaff 1... more Five areas are believed to be favorable for the occurrence of uranium deposits in the Flagstaff 1°x2° quadrangle. Areas favorable for uranium deposits in collapse breccia pipes are within the Coconino and Marble Plateaus and the Little River Valley. Three areas of Mesozoic sediments are deemed favorable for the occurrence of sandstone-type deposits. Uranium mineralization is present in lake-bed bearing

Research paper thumbnail of Geology, structure, and uranium deposits of the Flagstaff lºx2º quadrangle, Arizona

Research paper thumbnail of Precipitation variability of the Grand Canyon region, 1893 through 2009, and its implications for studying effects of gullying of Holocene terraces and associated archeological sites in Grand Canyon, Arizona

Research paper thumbnail of Late Holocene Alluvial Geomorphology of the Virgin River in the Zion National Park Area, Southwest Utah

Special Paper 310: Late Holocene alluvial geomorphology of the Virgin River in the Zion National Park area, Southwest Utah, 1996

... 3300 Penrose Place, PO Box 9140, Boulder, Colorado 80301 Printed in USA GSA Books Science Edi... more ... 3300 Penrose Place, PO Box 9140, Boulder, Colorado 80301 Printed in USA GSA Books Science Editor Abhijit Basu Library of Congress ... abundant gravel-size sediment from the ledge-forming Cretaceous-age sandstone in the headwaters of the basin (Sable and Hereford ...

Research paper thumbnail of Numerical Ages of Holocene Tributary Debris Fans Inferred from Dissolution Pitting on Carbonate Boulders in the Grand Canyon of Arizona

Quaternary Research, 1998

Colorado River in Grand Canyon National Park. Weakly acidic rainfall and the metabolic activity o... more Colorado River in Grand Canyon National Park. Weakly acidic rainfall and the metabolic activity of blue-green algae have produced roughly hemispheric dissolution pits as much as 2-cm deep on the initially smooth surfaces of the boulders. The average depth of dissolution pits increases with relative age of fan surfaces. The deepening rate averages 2.4 mm/1000 yr (standard error ‫؍‬ 0.2 mm/1000 yr), as calculated from several radiometrically dated surfaces and an archeological structure. This linear rate, which appears constant over at least the past 3000 yr, is consistent with field relations limiting the maximum age of the fans and with the physical chemistry of limestone dissolution. Dissolution-pit measurements (n ‫؍‬ 6973) were made on 617 boulders on 71 fan surfaces at the 26 largest debris fans in Grand Canyon. Among these fan surfaces, the average pit depth ranges from 1.2 to 17.4 mm, and the resulting pit dissolution ages range from 500 to 7300 cal yr B.P. Most (75%) surfaces are younger than 3000 yr, probably because of removal of older debris fans by the Colorado River. Many of the ages are close to 800, 1600, 2300, 3100, or 4300 cal yr B.P. If not the result of differential preservation of fan surfaces, this clustering implies periods of heightened debris-flow activity and increased precipitation. © 1998 University of Washington.

Research paper thumbnail of Channel evolution and hydrologic variations in the Colorado River basin: Factors influencing sediment and salt loads

Journal of Hydrology, 1991

Gellis, A., Hereford, R., Schumm, S.A. and Hayes, B.R., 1991. Channel evolution and hydrologic va... more Gellis, A., Hereford, R., Schumm, S.A. and Hayes, B.R., 1991. Channel evolution and hydrologic variations in the Colorado River basin: factors influencing sediment and salt loads. J. Hydrol., 124:317 344.

Research paper thumbnail of Precipitation history and ecosystem response to multidecadal precipitation variability in the Mojave Desert region, 1893–2001

Journal of Arid Environments, 2006

Precipitation varied substantially in the Mojave Desert through the 20th century in a manner broa... more Precipitation varied substantially in the Mojave Desert through the 20th century in a manner broadly similar to the other warm North American deserts. Episodes of drought and prolonged dry conditions (1893-1904, ca. 1942-1975, and 1999-present) alternated with relatively wet periods (1905-ca. 1941 and ca. 1976-1998), probably because of global-scale climate fluctuations. These are the El Nin˜o-Southern Oscillation that affects interannual climate and the Pacific Decadal Oscillation that evidently causes decadal-scale variability such as prolonged dry and wet episodes. Studies done in the late 20th century demonstrate that precipitation fluctuations affected populations of perennial vegetation, annuals, and small herbivores. Landscape rephotography reveals that several species, particularly creosote bush, increased in size and density during the ca. 1976-1998 wet period. A brief, intense drought from 1989 to 1991 and the ongoing drought caused widespread mortality of certain species; for example, chenopods and perennial grasses suffered up to 100% mortality. Drought pruning, the shedding of above-ground biomass to reduce carbon allocation, increased substantially during drought. Overall, drought had the greatest influence on the Mojave Desert ecosystem. r

Research paper thumbnail of Sediment yield and runoff frequency of small drainage basins in the Mojave Desert, U.S.A

Geomorphology, 2006

Sediment yield from small arid basins, particularly in the Mojave Desert, is largely unknown owin... more Sediment yield from small arid basins, particularly in the Mojave Desert, is largely unknown owing to the ephemeral nature of these fluvial systems and long recurrence interval of flow events. We examined 27 reservoirs in the northern and eastern Mojave Desert that trapped sediment from small (b1 km 2 ) drainage basins on alluvial fans over the past 100 yr, calculated annual sediment yield, and estimated the average recurrence interval (RI) of sediment-depositing flow events. These reservoirs formed where railbeds crossed and blocked channels, causing sediment to be trapped and stored upslope. Deposits are temporally constrained by the date of railway construction (1906)(1907)(1908)(1909)(1910), the presence of 137 Cs in the reservoir profile (post-1952 sediment), and either 1993, when some basins breached during regional flooding, or 2000-2001, when stratigraphic analyses were performed. Reservoir deposits are well stratified at most sites and have distinct fining-upward couplets indicative of discrete episodes of sediment-bearing runoff. Average RI of runoff events for these basins ranges from 2.6 to 7.3 yr and reflects the incidence of either intense or prolonged rainfall; more than half the runoff events occurred before 1963. A period of above-normal precipitation, from 1905 to 1941, may have increased runoff frequency in these basins. Mean sediment yield (9 to 48 tons km À 2 yr À 1 ) is an order of magnitude smaller than sediment yields calculated elsewhere and may be limited by reduced storm intensity, the presence of desert pavement, and shallow gradient of fan surfaces. Sediment yield decreases as drainage area increases, a trend typical of much larger drainage basins where sediment-transport processes constrain sediment yield. Coarse substrate and low-angle slopes of these alluvial fan surfaces likely limit sediment transport capacity through transmission losses and channel storage. D

Research paper thumbnail of Multiple constraints on the age of a Pleistocene lava dam across the Little Colorado River at Grand Falls, Arizona

Geological Society of America Bulletin, 2006

... about the growth of the field, including interpretation of the 100 m/my rate of regional down... more ... about the growth of the field, including interpretation of the 100 m/my rate of regional downcutting calculated from whole-rock K-Ar ages for samples from the two older lava dams along the Little Colorado River (Damon et al ... Corresponding author nancy.riggs{at}nau.edu. ...

Research paper thumbnail of Relation of sediment load and flood-plain formation to climatic variability, Paria River drainage basin, Utah and Arizona

Geological Society of America Bulletin, 1991

Research paper thumbnail of Historic variation of warm-season rainfall, Southern Colorado Plateau, Southwestern U.S.A

Climatic Change, 1992

Rainfall during the warm season (June 15-October 15) is the most important of the year in terms o... more Rainfall during the warm season (June 15-October 15) is the most important of the year in terms of flood generation and erosion in rivers of the southern Colorado Plateau. Fluvial erosion of the plateau decreased substantially in the 1930s to early 1940s, although the cause of this change has not been linked to variation of warm-season rainfall. This study shows that a decrease of warmseason rainfall frequency was coincident with and probably caused the decreased erosion by reducing the probability of large floods. Warm-season rainfall results from isolated thunderstorms associated with the Southwestern monsoon and from dissipating tropical cyclones and (or) cutoff low-pressure systems that produce widespread, general rainfall. Warm-season rainfall is typically normal to above normal during warm E1 Nifio-Southern Oscillation (ENSO) conditions. A network of 24 long-term precipitation gages was used to develop an index of standardized rainfall anomalies for the southern Colorado Plateau for the period 1900-85. The index shows that the occurrence of anomalously dry years increased and the occurrence of anomalously wet years decreased after the early 1930s, although 1939-41, 1972, and 1980-84 were anomalously wet. The decrease in warm-season rainfall after the early 1930s is related to a decrease in rainfall from dissipating tropical cyclones, shifts in the incidence of meridionat circulation in the upper atmosphere, and variability of ENSO conditions.

Research paper thumbnail of Tributary debris fans and the late Holocene alluvial chronology of the Colorado River, eastern Grand Canyon, Arizona

Geological Society of America Bulletin, 1996

... Select this article. B. Dubé,; GR Dunning,; K. Lauzière,; and JC Roddick. New insights into t... more ... Select this article. B. Dubé,; GR Dunning,; K. Lauzière,; and JC Roddick. New insights into the Appalachian Orogen from geology and geochronology along the Cape Ray fault zone, southwest Newfoundland. ... Select this article. William F. Outerbridge. ...