Petroglyphs weather at varying rates, compared tothe unengraved host rock into which they are car... more Petroglyphs weather at varying rates, compared tothe unengraved host rock into which they are carved. Most petroglyphs are significantly harder or significantly softer than surrounding rock, depending on the nature of weathering. Variability and intensity of weathering probably introduces error into radiocarbon, rock varnis and micreoerosion dating methods.
Abstract Weathering, or rock decay processes are at the center of the Critical Zone. The weatheri... more Abstract Weathering, or rock decay processes are at the center of the Critical Zone. The weathering engine modifies the Earth’s crust to adjust to surface atmospheric, hydrologic, and biotic conditions, relevant to the many fields that find interest in the Critical Zone. Regolith refers to the body of decayed rock or sediment, coincidental to (and parallel and synonymous with) the Critical Zone. Weathering processes are synergistic, involving combinations of mechanical and chemical decay, taking place mostly at a nano-scale boundary layer at the mineral surface. Numerous factors intrinsic to the rock itself and of the surrounding subsurface and subaerial environment influence the availability of weathering agents and the rates and efficacy of decay. When environmental conditions allow, the terrestrial Critical Zone, regolith, can attain significant thickness, tens of meters, in most environments. Rates of formation calculate the oldest regolith profiles to exceed one million years in age.
The Alentejo region of Portugal is known for a high concentration of Neolithic-aged megalithic mo... more The Alentejo region of Portugal is known for a high concentration of Neolithic-aged megalithic monuments: tombs (dolmens or antas) and ceremonial features such as standing stones (menhirs) and stone circles (cromleques). Concentrations of these monuments tend to be found on or near weathered granite terrains. Unloading slabs and remnant corestones appear to be the stones of preference for megalith makers in the Alentejo district of Portugal. Some of the stones may have been imported from distant sources, but most appear to be of local origin. In general, most stones do not appear to have been altered much from their original state as field stones. Weathering tests demonstrate that menhirs are essentially identical to native corestones. Manv menhirs still exhibit a soil line. The former subaerial side of the stone usually retains a thick growth of lichen, while the soil side remains oxidized. Newly exposed, antas and menhirs now suffer from enhanced weathering and erosion from atmosp...
Engineering Geology for Society and Territory - Volume 8, 2014
The "Villa of the Antonines", located at the 18th mile of the ancient Via Appia, is so far the le... more The "Villa of the Antonines", located at the 18th mile of the ancient Via Appia, is so far the least explored of the ancient Roman imperial residences in the area of the Alban Hills. Excavations at "Villa of the Antonines" permit an investigation of subsurface deterioration of cultural stone, addressing two primary questions: (1) What are the deterioration processes in the soil and sediment environment, and how do these compare to subaerial deterioration processes? (2) How might the deterioration impact other methodologies reliant on the analysis of the material, such as use and wear analysis, dating techniques, and provenience by chemical tracers? The deterioration characteristics of materials recovered thus far can be visually described. Marbles are discolored and exhibit a loss of polish and partial to extensive granular disintegration and powdering. Brick varies in color and composition due to manufacturing and material differences, but may also exhibit within-soil alteration. Glass tesserae exhibit frosting and pitting from chemical solution. Scanning electron microscopy (SEM) reveals surface microdeterioration such as pitting, etching, and glazing. Qualitative backscatter electron microscopy (BSEM) and energy dispersive spectroscopy (EDS) indicate the distribution of elements, including byproducts of chemical deterioration, likely within the soil environment.
High-intensity forest fires can degrade, collapse, or completely destroy clay minerals in soils, ... more High-intensity forest fires can degrade, collapse, or completely destroy clay minerals in soils, with signatures of these changes remaining for years after the burns. To ascertain immediate impacts of high-intensity fire on soil clay minerals and mineral recovery over time, soil from the 2002 Hayman, Colorado, fire was analyzed by X-ray diffraction. Sample locations included burned soil from within the perimeter of the fire, unburned soil near the origin, and soil from adjacent historic burns. The unburned soils contain mixtures of illite, mixed-layer illite/smectite and illite/vermiculite, kaolin, and mixed-layer chlorite. Surface soils (surface-7.7 cm) contain illite, mixed-layer illite/smectite, and kaolin. Subsurface soils (7.7-13.0 cm) contain mixed-layer illite/vermiculite, in addition to the same minerals found at the surface. Deep soils (13.0-27.0 cm) show disappearance of mixedlayer illite/smectite and illite/vermiculite and show evidence of the presence of mixed-layer chlorite. Comparisons between recently and historically burned soils and unburned soils showed slight trends in alterations of clay mineral structures in the surface soil, including alteration of the 001 illite peak, the 001 kaolin peak, and a decrease in the swelling component of mixed-layer illite/smectite. These trends indicate fire impacts the structure of soil clay minerals.
Great monumental places-Petra, Giza, Angkor, Stonehenge, Tikal, Macchu Picchu, Rapa Nui, to name ... more Great monumental places-Petra, Giza, Angkor, Stonehenge, Tikal, Macchu Picchu, Rapa Nui, to name a few-are links to our cultural past. They evoke a sense of wonderment for their aesthetic fascination if not for their seeming permanence over both cultural and physical landscapes. However, as with natural landforms, human constructs are subject to weathering and erosion. Indeed, many of our cultural resources suffer from serious deterioration, some natural, some enhanced by human impact. Groups from the United Nations to local civic and tourism assemblies are deeply interested in maintaining and preserving such cultural resources, from simple rock art to great temples. Geomorphologists trained in interacting systems, process and response to thresholds, rates of change over time, and spatial variation of weathering processes and effects are able to offer insight into how deterioration occurs and what can be done to ameliorate the impact.Review of recent literature and case studies presented here demonstrate methodological and theoretical advances that have resulted from the study of cultural stone weathering. Because the stone was carved at a known date to a ''baseline'' or zero-datum level, some of the simplest methods (e.g., assessing surface weathering features or measuring surface recession in the field) provide useful data on weathering rates and processes. Such data are difficult or impossible to obtain in ''natural'' settings. Cultural stone weathering studies demonstrate the importance of biotic and saline weathering agents and the significance of weathering factors such as exposure (microclimate) and human impact. More sophisticated methods confirm these observations, but also reveal discrepancies between field and laboratory studies. This brings up two important caveats for conservators and geomorphologists. For the conservator, are laboratory and natural setting studies really analogous and useful for assessing stone damage? For the geomorphologist, does cultural stone data have any real relevance to the natural environment? These are questions for future research and debate. In any event, cultural stone weathering studies have been productive for both geomorphologists and conservators. Continued collaboration and communication between the geomorphic, historic preservation, archaeological, and engineering research communities are encouraged.
Anthropogenic organic compounds and pollutants are routinely used to indicate human presence in a... more Anthropogenic organic compounds and pollutants are routinely used to indicate human presence in anthrosols, but little is understood about human impact on pedogenic processes. This article addresses human impacts on pedogenic rock and mineral weathering. Relatively unexplored from the soil perspective, human impacts on the weathering system can be locally significant and relevant to studies in geoarchaeology, geomorphology, and ecology. The article provides a theoretical framework for human-impacted weathering, and presents a case study of "anthroweathering" at a Hohokam pit house excavated in central Arizona. Mineral grains, sampled from within and outside the pit house, were observed using backscatter electron microscopy. A statistically significant difference was found between impacted and less-impacted samples, with more weathering under areas of greater human impact. Accordingly, soil profile descriptions suggest increased chemical activity within and under the pit house anthrosol. These observations attest to the potential application of anthroweathering toward the identification and analysis of cultural remains and toward an assessment of environmental degradation ᭧ 1999 John Wiley & Sons, Inc.
The upper reaches of the Big Flat Brook drainage, northwest of Kittatinny Mountain, contain a var... more The upper reaches of the Big Flat Brook drainage, northwest of Kittatinny Mountain, contain a variety of glacial, pro-glacial, and periglacial deposits from the Late Quaternary. The area is dominated by recessional moraines and ubiquitous ground moraine, along with meltwater deposits, drumlins, and possible postglacial periglacial features. We have identified a curious boulder-rich deposit in the vicinity of Lake Ocquittunk and Lake Wapalanne on upper Big Flat Brook. The area where these boulder deposits occur is mapped (1:24,000 surficial geology) as till. As mapped and observed, larger cobbles and boulders within the till are quartz-pebble conglomerate, quartzite, sandstone, and shale. The boulder-rich deposits differ from the typical till, however. Unlike the local till, which is more mixed in lithology, the boulder deposits are nearly exclusively Shawangunk conglomerate. The deposits are discontinuous, but appear to occur at a topographic level above the meltwater stream terraces. The boulders in the deposits lie partially embedded in soil, but are very closely spaced. The boulders range in size from ~20cm to over 100cm, and present a subrounded to subangular shape. There appears to be a fabric orientation of the boulders, NE-SW, with subsidiary orientations. As the boulder deposits differ from other mapped features in the area, we attempt to ascertain the origin for the deposits. Unique moraine dynamics, meltwater flood, periglacial slope movement, and slope-snow bank processes are possible explanations. Detailed examination of these boulder deposits will provide a finer explanation of the glacial and post-glacial geomorphic history of the area.
Weathering processes are partially responsible for a characteristic geomorphology that occurs in ... more Weathering processes are partially responsible for a characteristic geomorphology that occurs in the tropics and subtropics. Resistant landforms such as inselbergs, extreme solution processes such as silica karst, and deep weathering profiles with end stage weathering products such as laterite and kaolin are common features of tropical weathering. Many of these features also occur outside the tropics. In part, climate change and paleotectonics were responsible for tropical conditions in areas not now tropical. But, some processes assumed to require tropic conditions that are not so limited, sufficient moisture, and time sufficing for their development. This chapter reviews the weathering processes and distinctive landforms of the broadly defined tropics, and explores the debates over weathering factors as they pertain to tropic and extratropical environment.
Pedogenic and weathering processes are intricately related to paleoclimate evidence in loess. Soi... more Pedogenic and weathering processes are intricately related to paleoclimate evidence in loess. Soil processes (clay formation and translocation, carbonate concentration, and iron alteration and translocation) are all tied to weathering reactions that occur in the soil. Proxy indicators reveal environmental change, but the environment itself may alter the proxy indicators. Is the paleoclimate evidence biased by inherent complexity? One way to address this quandary is to investigate specific soil formation and weathering processes. This study applies quantified soil development indices and weathering indices and compares these against existing climate proxy indicators for the S1 Paleosol in the Chinese Loess Plateau. Six field locations were surveyed and sampled in two northwest-to-southeast transects in the Chinese Loess Plateau. A range of field data (horizonation, color, texture, structure, carbonate morphology) was used to calculate a profile development index modified from Harden&...
While most research on quartz weathering has focused primarily on surface textures and morphologi... more While most research on quartz weathering has focused primarily on surface textures and morphologies, very little is known about the internal weathering of quartz. This study demonstrates that internal weathering is ubiquitous in quartz. Internal weathering is measured in terms of porosity, which represents mass loss from the quartz grain, hence silica lost through dissolution. Mass loss calculated from porosity suggests higher-than-expected rates of quartz dissolution in the terrestrial environment. Internal weathering occurs through various grain defects, and is classified into several forms (in decreasing order of frequency): fractures, enlarged grain boundaries, holes, and networks. These features may be distinguished from occasional artifact voids left by laboratory procedures. The most intensely weathered grains exhibit large fractures and extensive networks, and occasionally contain secondary weathering products within the void areas. The presence of internal weathering in qua...
The genesis of detrital sediments could not take place without weathering. Both chemical and mech... more The genesis of detrital sediments could not take place without weathering. Both chemical and mechanical weathering processes work toward the fragmentation, disaggregation, and chemical alteration of rocks to form clastic particles (clay to boulder size) and solutes. Clastic particles are entrained into the sediment system by various geomorphic processes. Solutes indurate soils and near surface sediments as well as cementing buried sediments. The weathering genesis of particles and weathering of sediments becomes relevant to concerns within geomorphology and sedimentology, including the recognition of fine-grained particles derived from weathering, and the implications of sediment weathering on environmental factors and dating methods.
In this project, the urban heat island effect (UHI) was examined under current and
projected clim... more In this project, the urban heat island effect (UHI) was examined under current and projected climate conditions in the greater Newark, New Jersey region using a combination of spatial analyses of remotely-sensed thermal data and of meteorological station data. Mitigation strategies for the UHI, including increased urban vegetation and lighter-colored surfacing, were explored using CITYgreen, a GIS application developed by the American Forestry Association. The urban heat island effect is a reflection of the microclimatic changes brought about by human alterations of the Earth’s surface in densely populated areas. It is a good indicator of the sensitivity of the climate system to human forcing on a local level. Heat islands of varying extent and magnitude have been observed in most urbanized areas in the world. (Landsberg, 1981).
Anthropogenic organic compounds and pollutants are routinely used to indicate human presence in a... more Anthropogenic organic compounds and pollutants are routinely used to indicate human presence in anthrosols, but little is understood about human impact on pedogenic processes. This article addresses human impacts on pedogenic rock and mineral weathering. Relatively unexplored from the soil perspective, human impacts on the weathering system can be locally significant and relevant to studies in geoarchaeology, geomorphology, and ecology. The article provides a theoretical framework for human-impacted weathering, and presents a case study of “anthroweathering” at a Hohokam pit house excavated in central Arizona. Mineral grains, sampled from within and outside the pit house, were observed using backscatter electron microscopy. A statistically significant difference was found between impacted and less-impacted samples, with more weathering under areas of greater human impact. Accordingly, soil profile descriptions suggest increased chemical activity within and under the pit house anthrosol. These observations attest to the potential application of anthroweathering toward the identification and analysis of cultural remains and toward an assessment of environmental degradation
Quartz is regarded as one of the minerals most resistant to chemical weathering. Nevertheless, qu... more Quartz is regarded as one of the minerals most resistant to chemical weathering. Nevertheless, quartz does weather under certain conditions. Several geographic phenomena, including downstream sorting of fluvial sediments, the distribution of loess, and the absence of silica in tropical soils, may be directly or indirectly related to quartz weathering. Weathering may impact the use of quartz in geographic applications of geochronology and paleoenvironmental analysis. This paper defines the molecular-scale mechanisms of chemical weathering in quartz, and presents the first examination of quartz weathering in the terrestrial environment using high resolution transmission electron microscopy (HRTEM). HRTEM images illustrate crystalline disintegration, or amorphization, of exterior surfaces and internal fractures of quartz sand grains collected from tills of the Eastern Sierra Nevada, California. Of several alternative mechanisms, in situ hydration of the crystalline matrix is the most plausible for quartz amorphization. Scale and mineral structure appear to be prominent factors in quartz amorphization; microenvironment and weathering rates may also be significant, but data are insufficient to make more precise generalizations.
The prevailing theory used to explain geographical variability in weathering is based on visual c... more The prevailing theory used to explain geographical variability in weathering is based on visual correlations with climatic regions. For instance, mechanical weathering is assumed to predominate in warm and cold deserts. Yet this visual perspective fails to account for a diversity and quantity of data at the mineral-atmosphere-hydrosphere-biosphere interface where weathering processes actually occur. To address these discrepancies, a new model is proposed which views geographical variability in weathering as a function of synergistic biological, chemical, and physical processes that are controlled by factors that vary at the microscopic weathering boundary-layer. The new multivariate model better explains weathering observations at hygroscopic, capillary, pedogenic, landform, and landscape scales.
The " Villa of the Antonines " , located at the 18th mile of the ancient Via Appia, is so far the... more The " Villa of the Antonines " , located at the 18th mile of the ancient Via Appia, is so far the least explored of the ancient Roman imperial residences in the area of the Alban Hills. Excavations at " Villa of the Antonines " permit an investigation of subsurface deterioration of cultural stone, addressing two primary questions: (1) What are the deterioration processes in the soil and sediment environment, and how do these compare to subaerial deterioration processes? (2) How might the deterioration impact other methodologies reliant on the analysis of the material, such as use and wear analysis, dating techniques, and provenience by chemical tracers? The deterioration characteristics of materials recovered thus far can be visually described. Marbles are discolored and exhibit a loss of polish and partial to extensive granular disintegration and powdering. Brick varies in color and composition due to manufacturing and material differences, but may also exhibit within-soil alteration. Glass tesserae exhibit frosting and pitting from chemical solution. Scanning electron microscopy (SEM) reveals surface microdeterioration such as pitting, etching, and glazing. Qualitative backscatter electron microscopy (BSEM) and energy dispersive spectroscopy (EDS) indicate the distribution of elements, including byproducts of chemical deterioration, likely within the soil environment.
Petroglyphs weather at varying rates, compared tothe unengraved host rock into which they are car... more Petroglyphs weather at varying rates, compared tothe unengraved host rock into which they are carved. Most petroglyphs are significantly harder or significantly softer than surrounding rock, depending on the nature of weathering. Variability and intensity of weathering probably introduces error into radiocarbon, rock varnis and micreoerosion dating methods.
Abstract Weathering, or rock decay processes are at the center of the Critical Zone. The weatheri... more Abstract Weathering, or rock decay processes are at the center of the Critical Zone. The weathering engine modifies the Earth’s crust to adjust to surface atmospheric, hydrologic, and biotic conditions, relevant to the many fields that find interest in the Critical Zone. Regolith refers to the body of decayed rock or sediment, coincidental to (and parallel and synonymous with) the Critical Zone. Weathering processes are synergistic, involving combinations of mechanical and chemical decay, taking place mostly at a nano-scale boundary layer at the mineral surface. Numerous factors intrinsic to the rock itself and of the surrounding subsurface and subaerial environment influence the availability of weathering agents and the rates and efficacy of decay. When environmental conditions allow, the terrestrial Critical Zone, regolith, can attain significant thickness, tens of meters, in most environments. Rates of formation calculate the oldest regolith profiles to exceed one million years in age.
The Alentejo region of Portugal is known for a high concentration of Neolithic-aged megalithic mo... more The Alentejo region of Portugal is known for a high concentration of Neolithic-aged megalithic monuments: tombs (dolmens or antas) and ceremonial features such as standing stones (menhirs) and stone circles (cromleques). Concentrations of these monuments tend to be found on or near weathered granite terrains. Unloading slabs and remnant corestones appear to be the stones of preference for megalith makers in the Alentejo district of Portugal. Some of the stones may have been imported from distant sources, but most appear to be of local origin. In general, most stones do not appear to have been altered much from their original state as field stones. Weathering tests demonstrate that menhirs are essentially identical to native corestones. Manv menhirs still exhibit a soil line. The former subaerial side of the stone usually retains a thick growth of lichen, while the soil side remains oxidized. Newly exposed, antas and menhirs now suffer from enhanced weathering and erosion from atmosp...
Engineering Geology for Society and Territory - Volume 8, 2014
The "Villa of the Antonines", located at the 18th mile of the ancient Via Appia, is so far the le... more The "Villa of the Antonines", located at the 18th mile of the ancient Via Appia, is so far the least explored of the ancient Roman imperial residences in the area of the Alban Hills. Excavations at "Villa of the Antonines" permit an investigation of subsurface deterioration of cultural stone, addressing two primary questions: (1) What are the deterioration processes in the soil and sediment environment, and how do these compare to subaerial deterioration processes? (2) How might the deterioration impact other methodologies reliant on the analysis of the material, such as use and wear analysis, dating techniques, and provenience by chemical tracers? The deterioration characteristics of materials recovered thus far can be visually described. Marbles are discolored and exhibit a loss of polish and partial to extensive granular disintegration and powdering. Brick varies in color and composition due to manufacturing and material differences, but may also exhibit within-soil alteration. Glass tesserae exhibit frosting and pitting from chemical solution. Scanning electron microscopy (SEM) reveals surface microdeterioration such as pitting, etching, and glazing. Qualitative backscatter electron microscopy (BSEM) and energy dispersive spectroscopy (EDS) indicate the distribution of elements, including byproducts of chemical deterioration, likely within the soil environment.
High-intensity forest fires can degrade, collapse, or completely destroy clay minerals in soils, ... more High-intensity forest fires can degrade, collapse, or completely destroy clay minerals in soils, with signatures of these changes remaining for years after the burns. To ascertain immediate impacts of high-intensity fire on soil clay minerals and mineral recovery over time, soil from the 2002 Hayman, Colorado, fire was analyzed by X-ray diffraction. Sample locations included burned soil from within the perimeter of the fire, unburned soil near the origin, and soil from adjacent historic burns. The unburned soils contain mixtures of illite, mixed-layer illite/smectite and illite/vermiculite, kaolin, and mixed-layer chlorite. Surface soils (surface-7.7 cm) contain illite, mixed-layer illite/smectite, and kaolin. Subsurface soils (7.7-13.0 cm) contain mixed-layer illite/vermiculite, in addition to the same minerals found at the surface. Deep soils (13.0-27.0 cm) show disappearance of mixedlayer illite/smectite and illite/vermiculite and show evidence of the presence of mixed-layer chlorite. Comparisons between recently and historically burned soils and unburned soils showed slight trends in alterations of clay mineral structures in the surface soil, including alteration of the 001 illite peak, the 001 kaolin peak, and a decrease in the swelling component of mixed-layer illite/smectite. These trends indicate fire impacts the structure of soil clay minerals.
Great monumental places-Petra, Giza, Angkor, Stonehenge, Tikal, Macchu Picchu, Rapa Nui, to name ... more Great monumental places-Petra, Giza, Angkor, Stonehenge, Tikal, Macchu Picchu, Rapa Nui, to name a few-are links to our cultural past. They evoke a sense of wonderment for their aesthetic fascination if not for their seeming permanence over both cultural and physical landscapes. However, as with natural landforms, human constructs are subject to weathering and erosion. Indeed, many of our cultural resources suffer from serious deterioration, some natural, some enhanced by human impact. Groups from the United Nations to local civic and tourism assemblies are deeply interested in maintaining and preserving such cultural resources, from simple rock art to great temples. Geomorphologists trained in interacting systems, process and response to thresholds, rates of change over time, and spatial variation of weathering processes and effects are able to offer insight into how deterioration occurs and what can be done to ameliorate the impact.Review of recent literature and case studies presented here demonstrate methodological and theoretical advances that have resulted from the study of cultural stone weathering. Because the stone was carved at a known date to a ''baseline'' or zero-datum level, some of the simplest methods (e.g., assessing surface weathering features or measuring surface recession in the field) provide useful data on weathering rates and processes. Such data are difficult or impossible to obtain in ''natural'' settings. Cultural stone weathering studies demonstrate the importance of biotic and saline weathering agents and the significance of weathering factors such as exposure (microclimate) and human impact. More sophisticated methods confirm these observations, but also reveal discrepancies between field and laboratory studies. This brings up two important caveats for conservators and geomorphologists. For the conservator, are laboratory and natural setting studies really analogous and useful for assessing stone damage? For the geomorphologist, does cultural stone data have any real relevance to the natural environment? These are questions for future research and debate. In any event, cultural stone weathering studies have been productive for both geomorphologists and conservators. Continued collaboration and communication between the geomorphic, historic preservation, archaeological, and engineering research communities are encouraged.
Anthropogenic organic compounds and pollutants are routinely used to indicate human presence in a... more Anthropogenic organic compounds and pollutants are routinely used to indicate human presence in anthrosols, but little is understood about human impact on pedogenic processes. This article addresses human impacts on pedogenic rock and mineral weathering. Relatively unexplored from the soil perspective, human impacts on the weathering system can be locally significant and relevant to studies in geoarchaeology, geomorphology, and ecology. The article provides a theoretical framework for human-impacted weathering, and presents a case study of "anthroweathering" at a Hohokam pit house excavated in central Arizona. Mineral grains, sampled from within and outside the pit house, were observed using backscatter electron microscopy. A statistically significant difference was found between impacted and less-impacted samples, with more weathering under areas of greater human impact. Accordingly, soil profile descriptions suggest increased chemical activity within and under the pit house anthrosol. These observations attest to the potential application of anthroweathering toward the identification and analysis of cultural remains and toward an assessment of environmental degradation ᭧ 1999 John Wiley & Sons, Inc.
The upper reaches of the Big Flat Brook drainage, northwest of Kittatinny Mountain, contain a var... more The upper reaches of the Big Flat Brook drainage, northwest of Kittatinny Mountain, contain a variety of glacial, pro-glacial, and periglacial deposits from the Late Quaternary. The area is dominated by recessional moraines and ubiquitous ground moraine, along with meltwater deposits, drumlins, and possible postglacial periglacial features. We have identified a curious boulder-rich deposit in the vicinity of Lake Ocquittunk and Lake Wapalanne on upper Big Flat Brook. The area where these boulder deposits occur is mapped (1:24,000 surficial geology) as till. As mapped and observed, larger cobbles and boulders within the till are quartz-pebble conglomerate, quartzite, sandstone, and shale. The boulder-rich deposits differ from the typical till, however. Unlike the local till, which is more mixed in lithology, the boulder deposits are nearly exclusively Shawangunk conglomerate. The deposits are discontinuous, but appear to occur at a topographic level above the meltwater stream terraces. The boulders in the deposits lie partially embedded in soil, but are very closely spaced. The boulders range in size from ~20cm to over 100cm, and present a subrounded to subangular shape. There appears to be a fabric orientation of the boulders, NE-SW, with subsidiary orientations. As the boulder deposits differ from other mapped features in the area, we attempt to ascertain the origin for the deposits. Unique moraine dynamics, meltwater flood, periglacial slope movement, and slope-snow bank processes are possible explanations. Detailed examination of these boulder deposits will provide a finer explanation of the glacial and post-glacial geomorphic history of the area.
Weathering processes are partially responsible for a characteristic geomorphology that occurs in ... more Weathering processes are partially responsible for a characteristic geomorphology that occurs in the tropics and subtropics. Resistant landforms such as inselbergs, extreme solution processes such as silica karst, and deep weathering profiles with end stage weathering products such as laterite and kaolin are common features of tropical weathering. Many of these features also occur outside the tropics. In part, climate change and paleotectonics were responsible for tropical conditions in areas not now tropical. But, some processes assumed to require tropic conditions that are not so limited, sufficient moisture, and time sufficing for their development. This chapter reviews the weathering processes and distinctive landforms of the broadly defined tropics, and explores the debates over weathering factors as they pertain to tropic and extratropical environment.
Pedogenic and weathering processes are intricately related to paleoclimate evidence in loess. Soi... more Pedogenic and weathering processes are intricately related to paleoclimate evidence in loess. Soil processes (clay formation and translocation, carbonate concentration, and iron alteration and translocation) are all tied to weathering reactions that occur in the soil. Proxy indicators reveal environmental change, but the environment itself may alter the proxy indicators. Is the paleoclimate evidence biased by inherent complexity? One way to address this quandary is to investigate specific soil formation and weathering processes. This study applies quantified soil development indices and weathering indices and compares these against existing climate proxy indicators for the S1 Paleosol in the Chinese Loess Plateau. Six field locations were surveyed and sampled in two northwest-to-southeast transects in the Chinese Loess Plateau. A range of field data (horizonation, color, texture, structure, carbonate morphology) was used to calculate a profile development index modified from Harden&...
While most research on quartz weathering has focused primarily on surface textures and morphologi... more While most research on quartz weathering has focused primarily on surface textures and morphologies, very little is known about the internal weathering of quartz. This study demonstrates that internal weathering is ubiquitous in quartz. Internal weathering is measured in terms of porosity, which represents mass loss from the quartz grain, hence silica lost through dissolution. Mass loss calculated from porosity suggests higher-than-expected rates of quartz dissolution in the terrestrial environment. Internal weathering occurs through various grain defects, and is classified into several forms (in decreasing order of frequency): fractures, enlarged grain boundaries, holes, and networks. These features may be distinguished from occasional artifact voids left by laboratory procedures. The most intensely weathered grains exhibit large fractures and extensive networks, and occasionally contain secondary weathering products within the void areas. The presence of internal weathering in qua...
The genesis of detrital sediments could not take place without weathering. Both chemical and mech... more The genesis of detrital sediments could not take place without weathering. Both chemical and mechanical weathering processes work toward the fragmentation, disaggregation, and chemical alteration of rocks to form clastic particles (clay to boulder size) and solutes. Clastic particles are entrained into the sediment system by various geomorphic processes. Solutes indurate soils and near surface sediments as well as cementing buried sediments. The weathering genesis of particles and weathering of sediments becomes relevant to concerns within geomorphology and sedimentology, including the recognition of fine-grained particles derived from weathering, and the implications of sediment weathering on environmental factors and dating methods.
In this project, the urban heat island effect (UHI) was examined under current and
projected clim... more In this project, the urban heat island effect (UHI) was examined under current and projected climate conditions in the greater Newark, New Jersey region using a combination of spatial analyses of remotely-sensed thermal data and of meteorological station data. Mitigation strategies for the UHI, including increased urban vegetation and lighter-colored surfacing, were explored using CITYgreen, a GIS application developed by the American Forestry Association. The urban heat island effect is a reflection of the microclimatic changes brought about by human alterations of the Earth’s surface in densely populated areas. It is a good indicator of the sensitivity of the climate system to human forcing on a local level. Heat islands of varying extent and magnitude have been observed in most urbanized areas in the world. (Landsberg, 1981).
Anthropogenic organic compounds and pollutants are routinely used to indicate human presence in a... more Anthropogenic organic compounds and pollutants are routinely used to indicate human presence in anthrosols, but little is understood about human impact on pedogenic processes. This article addresses human impacts on pedogenic rock and mineral weathering. Relatively unexplored from the soil perspective, human impacts on the weathering system can be locally significant and relevant to studies in geoarchaeology, geomorphology, and ecology. The article provides a theoretical framework for human-impacted weathering, and presents a case study of “anthroweathering” at a Hohokam pit house excavated in central Arizona. Mineral grains, sampled from within and outside the pit house, were observed using backscatter electron microscopy. A statistically significant difference was found between impacted and less-impacted samples, with more weathering under areas of greater human impact. Accordingly, soil profile descriptions suggest increased chemical activity within and under the pit house anthrosol. These observations attest to the potential application of anthroweathering toward the identification and analysis of cultural remains and toward an assessment of environmental degradation
Quartz is regarded as one of the minerals most resistant to chemical weathering. Nevertheless, qu... more Quartz is regarded as one of the minerals most resistant to chemical weathering. Nevertheless, quartz does weather under certain conditions. Several geographic phenomena, including downstream sorting of fluvial sediments, the distribution of loess, and the absence of silica in tropical soils, may be directly or indirectly related to quartz weathering. Weathering may impact the use of quartz in geographic applications of geochronology and paleoenvironmental analysis. This paper defines the molecular-scale mechanisms of chemical weathering in quartz, and presents the first examination of quartz weathering in the terrestrial environment using high resolution transmission electron microscopy (HRTEM). HRTEM images illustrate crystalline disintegration, or amorphization, of exterior surfaces and internal fractures of quartz sand grains collected from tills of the Eastern Sierra Nevada, California. Of several alternative mechanisms, in situ hydration of the crystalline matrix is the most plausible for quartz amorphization. Scale and mineral structure appear to be prominent factors in quartz amorphization; microenvironment and weathering rates may also be significant, but data are insufficient to make more precise generalizations.
The prevailing theory used to explain geographical variability in weathering is based on visual c... more The prevailing theory used to explain geographical variability in weathering is based on visual correlations with climatic regions. For instance, mechanical weathering is assumed to predominate in warm and cold deserts. Yet this visual perspective fails to account for a diversity and quantity of data at the mineral-atmosphere-hydrosphere-biosphere interface where weathering processes actually occur. To address these discrepancies, a new model is proposed which views geographical variability in weathering as a function of synergistic biological, chemical, and physical processes that are controlled by factors that vary at the microscopic weathering boundary-layer. The new multivariate model better explains weathering observations at hygroscopic, capillary, pedogenic, landform, and landscape scales.
The " Villa of the Antonines " , located at the 18th mile of the ancient Via Appia, is so far the... more The " Villa of the Antonines " , located at the 18th mile of the ancient Via Appia, is so far the least explored of the ancient Roman imperial residences in the area of the Alban Hills. Excavations at " Villa of the Antonines " permit an investigation of subsurface deterioration of cultural stone, addressing two primary questions: (1) What are the deterioration processes in the soil and sediment environment, and how do these compare to subaerial deterioration processes? (2) How might the deterioration impact other methodologies reliant on the analysis of the material, such as use and wear analysis, dating techniques, and provenience by chemical tracers? The deterioration characteristics of materials recovered thus far can be visually described. Marbles are discolored and exhibit a loss of polish and partial to extensive granular disintegration and powdering. Brick varies in color and composition due to manufacturing and material differences, but may also exhibit within-soil alteration. Glass tesserae exhibit frosting and pitting from chemical solution. Scanning electron microscopy (SEM) reveals surface microdeterioration such as pitting, etching, and glazing. Qualitative backscatter electron microscopy (BSEM) and energy dispersive spectroscopy (EDS) indicate the distribution of elements, including byproducts of chemical deterioration, likely within the soil environment.
Uploads
Papers by Greg Pope
projected climate conditions in the greater Newark, New Jersey region using a combination of spatial analyses of remotely-sensed thermal data and of meteorological station data. Mitigation strategies for the UHI, including increased urban vegetation and lighter-colored surfacing, were explored using CITYgreen, a GIS application developed by the American Forestry Association. The urban heat island effect is a reflection of the microclimatic changes brought about by human alterations of the Earth’s surface in densely populated areas. It is a good indicator of the sensitivity of the climate system to human forcing on a local level. Heat islands of varying extent and magnitude have been observed in most urbanized areas in the world. (Landsberg, 1981).
projected climate conditions in the greater Newark, New Jersey region using a combination of spatial analyses of remotely-sensed thermal data and of meteorological station data. Mitigation strategies for the UHI, including increased urban vegetation and lighter-colored surfacing, were explored using CITYgreen, a GIS application developed by the American Forestry Association. The urban heat island effect is a reflection of the microclimatic changes brought about by human alterations of the Earth’s surface in densely populated areas. It is a good indicator of the sensitivity of the climate system to human forcing on a local level. Heat islands of varying extent and magnitude have been observed in most urbanized areas in the world. (Landsberg, 1981).