ABSTRACT. Eleven cirque glaciers and associated deposits within the granitic Arrigetch Peaks of t... more ABSTRACT. Eleven cirque glaciers and associated deposits within the granitic Arrigetch Peaks of the west-central Brooks Range face north, minimizing insolation. Shading by surrounding mountainous terrain decreases insolation on these landforms even more significant-ly, favoring the formation of glacier-cored moraines. Comparison of glacier photographs taken in 191 1, 1962, and 1979 reveals a record of decelerating recession. Geomorphic and lichenometric mapping suggests at least three to possibly eight phases of Holocene glacial expansion. These date between- 5000 and 300 yr B.P., based on the application of a central Brooks Range Rhizocarpon geographicurn growth curve. RfiSUMfi. Dans les hauts plateaux granitique Arrigetch situes dans la partie centre-ouest de la chaine Brooks, on retrouve onze cirques glaciers et leur depots orientes vers le nord, minimisant ainsi l'ensoleillement. L'ombre produite par les terrains montagneux limitrophe diminue cet ensoleillement de faço...
Remote sensing allows the petroleum industry to make better and quicker interpretations of geolog... more Remote sensing allows the petroleum industry to make better and quicker interpretations of geological and environmental conditions in areas of present and future operations. Often remote sensing (including aerial photographs) is required because existing maps are out-of-date, too small of scale, or provide only limited information. Implementing remote sensing can lead to lower project costs and reduced risk. The same satellite and airborne data can be used effectively for both geological and environmental applications. For example, earth scientists can interpret new lithologic, structural, and geomorphic information from near-infrared and radar imagery in terrains as diverse as barren desert and tropical jungle. Environmental applications with these and other imagery include establishing baselines, assessing impact by documenting changes through time, and mapping land-use, habitat, and vegetation. Higher resolution sensors provide an up-to-date overview of onshore and offshore petroleum facilities, whereas sensors capable of oblique viewing can be used to generate topographic maps. Geological application in Yemen involved merging Landsat TM and SPOT imagery to obtain exceptional lithologic discrimination. In the Congo, a topographic map to plan field operations was interpreted from the overlapping radar strips. Landsat MSS and TM, SPOT, and Russian satellite images with new aerial photographs are being used inmore » the Tengiz supergiant oil field of Kazakhstan to help establish an environmental baseline, generate a base map, locate wells, plan facilities, and support a geographical information system (GIS). In the Niger delta, Landsat TM and SPOT are being used to plan pipeline routes and seismic lines, and to monitor rapid shoreline changes and population growth. Accurate coastlines, facility locations, and shoreline types are being extracted from satellite images for use in oil spill models.« less
Geologic mapping in frontier areas can be done accurately and efficiently by integrating various ... more Geologic mapping in frontier areas can be done accurately and efficiently by integrating various remote sensing and photometric methods with field mapping. Interpretations of Landsat, airborne radar, and aerial photographs were integrated with field mapping to geologically map part of a northwest-directed fold-thrust belt in the Eastern Cordillera, southwest of Santafe de Bogota, Colombia. Each sensor provided particular advantages: (1)
Recession of “Golden Eagle” glacier in the central Brooks Range is exposing undisturbed lichen-co... more Recession of “Golden Eagle” glacier in the central Brooks Range is exposing undisturbed lichen-covered boulders. Radiocarbon analysis of dead moss surrounding these boulders dates a Neoglacial advance across this site at 1120±180 years b.p Measurements of the preserved lichens indicate that a minimum ice-free period of 1500–2500 years preceded this glacial expansion.
The east-central Brooks Range was just high enough to support cirque glacierization during the mi... more The east-central Brooks Range was just high enough to support cirque glacierization during the middle to late Holocene; presently glaciers are shrinking. The 133 glaciers in the field area are all above 1500 m altitude, and those fronted by stable moraines occur on a trend ...
... 12, No. 3, 1980, pp. 245-264 A LICHENOMETRIC DATING CURVE AND ITS APPLICATION TO HOLOCENE GLA... more ... 12, No. 3, 1980, pp. 245-264 A LICHENOMETRIC DATING CURVE AND ITS APPLICATION TO HOLOCENE GLACIER STUDIES IN THE CENTRAL BROOKS RANGE, ALASKA ... In Alaska it has been applied in the central Alaska Range (Reger and Pewe, 1969) and in the St. ...
Developments in Palaeontology and Stratigraphy, 1984
Abstract Lichenometry is a dating technique that uses lichens to obtain estimates of relative or ... more Abstract Lichenometry is a dating technique that uses lichens to obtain estimates of relative or absolute ages of rock-bearing substrates. It is based on the general assumptions that: a) stabilization and succeeding colonization of lichen-free rocks occur shortly after deposition and b) subsequent lichen growth occurs with a predictable pattern as a function of time. Species often reach ages of several thousand years, perhaps even to ≃ 9000 yr BP. Searches of bouldery Holocene moraines fronting small cirque glaciers in the arctic and alpine terrain of the central Brooks Range reveal patterns of selected lichen species consistent on the basis of maximum thallus diameters. These patterns show close parallelism to ridges marking successive ice-marginal positions. They have been mapped along with lichen trimline and density data as isophyses or graphed as frequency distributions to yield relative ages and modes of movement for over 50 glaciers. Absolute ages have been derived through develooment of a lichen growth curve based largely on the commonly used species Rhizocarpon geographicum s. l. , and the fast-growing Alectoria minuscula/pubescens . The R. geographicum curve has a “great (rapid) period” of growth ∼200 years. This part of the curve is controlled indirectly by historic and dendrochronologic data as well as by direct measurements of the Alectoria species which grows seven times faster. The subsequent linear (slower) growth phase of R. geographicum approximates 3 mm per century and is calibrated to 1300 yr BP by radiocarbon dates. This lichen factor of “3” is comparable to those from southern Alaska, Baffin Island, Swedish Lapland, and the Colorado Front Range. A colonization period of ∼30 years following substrate stabilization is built into the curve. We have computed surface ice velocity by measuring lichens along 1200 m of a supraglacial boulder train. Lichenometric maps of moraines have been used to reconstruct former glaciers. Lichenometry and radiocarbon analysis of vegetation emerging from beneath a retreating ice margin has provided a chronology of glacial advance and retreat spanning the last 2500 years. A regional synthesis of data suggests a complex glacial chronology involving seven periods of expansion during the past 4500 yr BP. In addition to glacial studies, we have made considerable use of lichens to indicate substrate stability and to estimate age of rock glaciers as well as other periglacial landforms.
The growth of 92 Rhizocarpon geographicum s.l. and 57 Alectoria minuscula Nyl. lichens was measur... more The growth of 92 Rhizocarpon geographicum s.l. and 57 Alectoria minuscula Nyl. lichens was measured over 4 to 6 yr in the Atigun Pass region of the central Brooks Range, Alaska. Absolute growth rates of R. geographicum s.l. were inversely related to thallus diameter and ranged from 0.35 to near 0 mm yr-1. In contrast, A. minuscula growth rates were directly related to diameter and ranged from 0.14 to 2.01 mm yr-1. A growth curve derived from mean rates of R. geographicum s.l. growth is similar to the indirectly controlled lichenometric dating curve for this region, but cannot yet be used to modify ages assigned to Holocene deposits. The derived growth curve for A. minuscula closely resembles those from the eastern Canadian
Petroleum companies can use high performance, airborne hyperspectral technology as a cost- effect... more Petroleum companies can use high performance, airborne hyperspectral technology as a cost- effective tool to improve evaluation of downstream assets, environmentally impacted areas, and terrain characterized by hydrocarbon-seepage. VNIR-SWIR data cubes acquired during Geosat's Hyperspectral Group Shoot 1998 contain new information about manmade facilities and oil- productive geologic structures that is not readily available from other sources. For exploration, a Southern California area with significant historic oil production was evaluated. Here Sulphur Mt. has oil seeps documented on a published geologic map. A spectrally unique airborne signature was spatially associated these published oil seeps. A very similar spectral signature was found 20 km east within clearings on a heavily vegetated flank of an anticline and at the anticline's plunging nose. In late 1999 the nose of the anticline was visited and many active seeps and ponding of oil were documented. A new Geosat ...
Lichenometric dating of moraines deposited by eight glaciers in the northeastern Brooks Range sug... more Lichenometric dating of moraines deposited by eight glaciers in the northeastern Brooks Range suggests major glacial advances or stillstands at about 2600, 1000, 450, and 60 lichenometric (L) years BP. The latter two advances of the early-middle and latest part of the 'Little Ice Age', respectively, formed promi nent moraines at all glaciers studied. In response to overall twentieth-century warming, these glaciers have retreated at average rates of 2 to 19 m yr-1 from the distinct ridges formed in AD 1890. Glacier thinning at rates of 0.7 to 0.9 m yr-1 accounts for over 90% of the ice loss.
Page 1. Chronology of Holocene glaciation, central Brooks Range, Alaska JAMES M. ELLIS* PARKER E.... more Page 1. Chronology of Holocene glaciation, central Brooks Range, Alaska JAMES M. ELLIS* PARKER E. CALKIN Department of Geological Sciences, State University of New York at Buffalo, Buffalo, New York 14226 ABSTRACT ...
Description/Abstract In 1983, Gulf and Ecopetrol undertook a regional hydrocarbon evaluation of n... more Description/Abstract In 1983, Gulf and Ecopetrol undertook a regional hydrocarbon evaluation of northwestern Colombia, during the course of which much of the Sinu basin was mapped by field geologists aided by low-altitude aerial photographs. Additional ...
ABSTRACT. Eleven cirque glaciers and associated deposits within the granitic Arrigetch Peaks of t... more ABSTRACT. Eleven cirque glaciers and associated deposits within the granitic Arrigetch Peaks of the west-central Brooks Range face north, minimizing insolation. Shading by surrounding mountainous terrain decreases insolation on these landforms even more significant-ly, favoring the formation of glacier-cored moraines. Comparison of glacier photographs taken in 191 1, 1962, and 1979 reveals a record of decelerating recession. Geomorphic and lichenometric mapping suggests at least three to possibly eight phases of Holocene glacial expansion. These date between- 5000 and 300 yr B.P., based on the application of a central Brooks Range Rhizocarpon geographicurn growth curve. RfiSUMfi. Dans les hauts plateaux granitique Arrigetch situes dans la partie centre-ouest de la chaine Brooks, on retrouve onze cirques glaciers et leur depots orientes vers le nord, minimisant ainsi l'ensoleillement. L'ombre produite par les terrains montagneux limitrophe diminue cet ensoleillement de faço...
Remote sensing allows the petroleum industry to make better and quicker interpretations of geolog... more Remote sensing allows the petroleum industry to make better and quicker interpretations of geological and environmental conditions in areas of present and future operations. Often remote sensing (including aerial photographs) is required because existing maps are out-of-date, too small of scale, or provide only limited information. Implementing remote sensing can lead to lower project costs and reduced risk. The same satellite and airborne data can be used effectively for both geological and environmental applications. For example, earth scientists can interpret new lithologic, structural, and geomorphic information from near-infrared and radar imagery in terrains as diverse as barren desert and tropical jungle. Environmental applications with these and other imagery include establishing baselines, assessing impact by documenting changes through time, and mapping land-use, habitat, and vegetation. Higher resolution sensors provide an up-to-date overview of onshore and offshore petroleum facilities, whereas sensors capable of oblique viewing can be used to generate topographic maps. Geological application in Yemen involved merging Landsat TM and SPOT imagery to obtain exceptional lithologic discrimination. In the Congo, a topographic map to plan field operations was interpreted from the overlapping radar strips. Landsat MSS and TM, SPOT, and Russian satellite images with new aerial photographs are being used inmore » the Tengiz supergiant oil field of Kazakhstan to help establish an environmental baseline, generate a base map, locate wells, plan facilities, and support a geographical information system (GIS). In the Niger delta, Landsat TM and SPOT are being used to plan pipeline routes and seismic lines, and to monitor rapid shoreline changes and population growth. Accurate coastlines, facility locations, and shoreline types are being extracted from satellite images for use in oil spill models.« less
Geologic mapping in frontier areas can be done accurately and efficiently by integrating various ... more Geologic mapping in frontier areas can be done accurately and efficiently by integrating various remote sensing and photometric methods with field mapping. Interpretations of Landsat, airborne radar, and aerial photographs were integrated with field mapping to geologically map part of a northwest-directed fold-thrust belt in the Eastern Cordillera, southwest of Santafe de Bogota, Colombia. Each sensor provided particular advantages: (1)
Recession of “Golden Eagle” glacier in the central Brooks Range is exposing undisturbed lichen-co... more Recession of “Golden Eagle” glacier in the central Brooks Range is exposing undisturbed lichen-covered boulders. Radiocarbon analysis of dead moss surrounding these boulders dates a Neoglacial advance across this site at 1120±180 years b.p Measurements of the preserved lichens indicate that a minimum ice-free period of 1500–2500 years preceded this glacial expansion.
The east-central Brooks Range was just high enough to support cirque glacierization during the mi... more The east-central Brooks Range was just high enough to support cirque glacierization during the middle to late Holocene; presently glaciers are shrinking. The 133 glaciers in the field area are all above 1500 m altitude, and those fronted by stable moraines occur on a trend ...
... 12, No. 3, 1980, pp. 245-264 A LICHENOMETRIC DATING CURVE AND ITS APPLICATION TO HOLOCENE GLA... more ... 12, No. 3, 1980, pp. 245-264 A LICHENOMETRIC DATING CURVE AND ITS APPLICATION TO HOLOCENE GLACIER STUDIES IN THE CENTRAL BROOKS RANGE, ALASKA ... In Alaska it has been applied in the central Alaska Range (Reger and Pewe, 1969) and in the St. ...
Developments in Palaeontology and Stratigraphy, 1984
Abstract Lichenometry is a dating technique that uses lichens to obtain estimates of relative or ... more Abstract Lichenometry is a dating technique that uses lichens to obtain estimates of relative or absolute ages of rock-bearing substrates. It is based on the general assumptions that: a) stabilization and succeeding colonization of lichen-free rocks occur shortly after deposition and b) subsequent lichen growth occurs with a predictable pattern as a function of time. Species often reach ages of several thousand years, perhaps even to ≃ 9000 yr BP. Searches of bouldery Holocene moraines fronting small cirque glaciers in the arctic and alpine terrain of the central Brooks Range reveal patterns of selected lichen species consistent on the basis of maximum thallus diameters. These patterns show close parallelism to ridges marking successive ice-marginal positions. They have been mapped along with lichen trimline and density data as isophyses or graphed as frequency distributions to yield relative ages and modes of movement for over 50 glaciers. Absolute ages have been derived through develooment of a lichen growth curve based largely on the commonly used species Rhizocarpon geographicum s. l. , and the fast-growing Alectoria minuscula/pubescens . The R. geographicum curve has a “great (rapid) period” of growth ∼200 years. This part of the curve is controlled indirectly by historic and dendrochronologic data as well as by direct measurements of the Alectoria species which grows seven times faster. The subsequent linear (slower) growth phase of R. geographicum approximates 3 mm per century and is calibrated to 1300 yr BP by radiocarbon dates. This lichen factor of “3” is comparable to those from southern Alaska, Baffin Island, Swedish Lapland, and the Colorado Front Range. A colonization period of ∼30 years following substrate stabilization is built into the curve. We have computed surface ice velocity by measuring lichens along 1200 m of a supraglacial boulder train. Lichenometric maps of moraines have been used to reconstruct former glaciers. Lichenometry and radiocarbon analysis of vegetation emerging from beneath a retreating ice margin has provided a chronology of glacial advance and retreat spanning the last 2500 years. A regional synthesis of data suggests a complex glacial chronology involving seven periods of expansion during the past 4500 yr BP. In addition to glacial studies, we have made considerable use of lichens to indicate substrate stability and to estimate age of rock glaciers as well as other periglacial landforms.
The growth of 92 Rhizocarpon geographicum s.l. and 57 Alectoria minuscula Nyl. lichens was measur... more The growth of 92 Rhizocarpon geographicum s.l. and 57 Alectoria minuscula Nyl. lichens was measured over 4 to 6 yr in the Atigun Pass region of the central Brooks Range, Alaska. Absolute growth rates of R. geographicum s.l. were inversely related to thallus diameter and ranged from 0.35 to near 0 mm yr-1. In contrast, A. minuscula growth rates were directly related to diameter and ranged from 0.14 to 2.01 mm yr-1. A growth curve derived from mean rates of R. geographicum s.l. growth is similar to the indirectly controlled lichenometric dating curve for this region, but cannot yet be used to modify ages assigned to Holocene deposits. The derived growth curve for A. minuscula closely resembles those from the eastern Canadian
Petroleum companies can use high performance, airborne hyperspectral technology as a cost- effect... more Petroleum companies can use high performance, airborne hyperspectral technology as a cost- effective tool to improve evaluation of downstream assets, environmentally impacted areas, and terrain characterized by hydrocarbon-seepage. VNIR-SWIR data cubes acquired during Geosat's Hyperspectral Group Shoot 1998 contain new information about manmade facilities and oil- productive geologic structures that is not readily available from other sources. For exploration, a Southern California area with significant historic oil production was evaluated. Here Sulphur Mt. has oil seeps documented on a published geologic map. A spectrally unique airborne signature was spatially associated these published oil seeps. A very similar spectral signature was found 20 km east within clearings on a heavily vegetated flank of an anticline and at the anticline's plunging nose. In late 1999 the nose of the anticline was visited and many active seeps and ponding of oil were documented. A new Geosat ...
Lichenometric dating of moraines deposited by eight glaciers in the northeastern Brooks Range sug... more Lichenometric dating of moraines deposited by eight glaciers in the northeastern Brooks Range suggests major glacial advances or stillstands at about 2600, 1000, 450, and 60 lichenometric (L) years BP. The latter two advances of the early-middle and latest part of the 'Little Ice Age', respectively, formed promi nent moraines at all glaciers studied. In response to overall twentieth-century warming, these glaciers have retreated at average rates of 2 to 19 m yr-1 from the distinct ridges formed in AD 1890. Glacier thinning at rates of 0.7 to 0.9 m yr-1 accounts for over 90% of the ice loss.
Page 1. Chronology of Holocene glaciation, central Brooks Range, Alaska JAMES M. ELLIS* PARKER E.... more Page 1. Chronology of Holocene glaciation, central Brooks Range, Alaska JAMES M. ELLIS* PARKER E. CALKIN Department of Geological Sciences, State University of New York at Buffalo, Buffalo, New York 14226 ABSTRACT ...
Description/Abstract In 1983, Gulf and Ecopetrol undertook a regional hydrocarbon evaluation of n... more Description/Abstract In 1983, Gulf and Ecopetrol undertook a regional hydrocarbon evaluation of northwestern Colombia, during the course of which much of the Sinu basin was mapped by field geologists aided by low-altitude aerial photographs. Additional ...
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Papers by James M Ellis