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Alba Patera has some of the longest lava tubes over some of the shallowest slopes on Mars. We use... more Alba Patera has some of the longest lava tubes over some of the shallowest slopes on Mars. We use Mars Orbiter Laser Altimeter (MOLA) topography to model eruption rates for several Alba Patera lava tubes and compare them within Alba and with flows from other martian volcanic regions. Additional information is contained in the original extended abstract.
Deciphering the Mars water history is important to understanding the planet's geological evol... more Deciphering the Mars water history is important to understanding the planet's geological evolution and whether it could have sustained life. Channel features on Mars, such as the features documented in Kasei Valles, are generally accepted as evidence for water flowing over the Mars surface in the past [1]. However, not all channels are the product of fluvial processes and many can be interpreted as having a volcanic origin [2]. This research involves studying channel features on the flanks of the Ascraeus Mons volcano, which is a part of the Tharsis province. Numerous sinuous channels exist on the rift apron of Ascraeus Mons and they have been interpreted as either fluvial [3] or volcanic [4,5]. The channels originate from pits and linear depressions and extend for many 100 s of km downslope. Mapping the proximal to distal morphology of the complete channel and determining its relationship with other features on the apron provides evidence for the processes of formation and thei...
Introduction: Observations of migrating sand ripples and dunes on Mars [1] show that aeolian proc... more Introduction: Observations of migrating sand ripples and dunes on Mars [1] show that aeolian processes continue to shape the surface of the planet. Transverse aeolian ridges (TARs) are a unique class of stable aeolian bedform with a wide variety of morphologies [e.g., 2] and an unknown particle size distribution. Rover observations on the surface of Mars can provide insight into their local characteristics [3], but the sedimentology of TARs is likely to vary between locations. Geissler et al. [4] hypothesized that martian TARs originate from indurated dust deposits. Because of their stability, morphology and formation mechanisms, a number of large wavelength and amplitude aeolian megaripples with granule to gravel-sized particles have been used as terrestrial analogs for martian TARs [e.g., 5]. The Lut Desert of Iran, containing megaripples composed of 3–4 mm sized grains, has also emerged as a site of martian morphological comparisons [6, 7].
ABSTRACT The fracture patterns of lava flows exhibit unique structure associated with emplacement... more ABSTRACT The fracture patterns of lava flows exhibit unique structure associated with emplacement, shown here from high-resolution 3D models generated from field photos.
Wetlands, 2011
Sediment pollution is one of the most important contributors to the degradation of the Chesapeake... more Sediment pollution is one of the most important contributors to the degradation of the Chesapeake Bay. The Susquehanna River is one of the main sources of sediment to the Bay and this source could dramatically increase in the future. The reservoirs on the Susquehanna River are almost at sediment-storage capacity. The lowest reservoir (Conowingo) could be at capacity within a few decades (Langland and Hainly 1997). Once this occurs little sediment will be trapped and prevented from entering the Bay. Sediment continues to be supplied to the river system from across the watershed. Understanding the sources of this sediment, as well as the processes contributing to the continued flow of sediment, are crucial if efforts to restore the Bay's ecosystem are to be successful. Our study has focused on one of the sub-basins of the Susquehanna River located in Lancaster County, Pennsylvania. We have examined the spatial and temporal distribution of sediment in the stream channel and floodplain and linked this information to changes in the landscape over the last several thousand years. Typically we see coarse-grained channel lag deposits formed by lateral migration of streams which are overlain by predominately fine-grained organic-rich (including large logs) sediment that accumulated slowly over several thousand years (based on radiocarbon ages). Deforestation resulting from European occupation beginning in the early 1700's caused a significant increase in the rate of sediment deposition in the floodplain and a decrease in the organic content of the sediment. Debris flows from the surrounding hillslopes resulted in matrix-supported conglomerates within the floodplain sediments. Modifications to the stream channels to facilitate agriculture were also common. More recent landscape changes resulting from suburbanization have resulted in complex spatial and temporal responses in the stream system. Initially, sediment deposition in the channels increased, however changes in land development practices have resulted in increased peak stream flows and the remobilization of the sediment from the stream channels, streambanks, and B. A. LePage (ed.
Alba Patera has some of the longest lava tubes over some of the shallowest slopes on Mars. We use... more Alba Patera has some of the longest lava tubes over some of the shallowest slopes on Mars. We use Mars Orbiter Laser Altimeter (MOLA) topography to model eruption rates for several Alba Patera lava tubes and compare them within Alba and with flows from other martian volcanic regions. Additional information is contained in the original extended abstract.
Deciphering the Mars water history is important to understanding the planet's geological evol... more Deciphering the Mars water history is important to understanding the planet's geological evolution and whether it could have sustained life. Channel features on Mars, such as the features documented in Kasei Valles, are generally accepted as evidence for water flowing over the Mars surface in the past [1]. However, not all channels are the product of fluvial processes and many can be interpreted as having a volcanic origin [2]. This research involves studying channel features on the flanks of the Ascraeus Mons volcano, which is a part of the Tharsis province. Numerous sinuous channels exist on the rift apron of Ascraeus Mons and they have been interpreted as either fluvial [3] or volcanic [4,5]. The channels originate from pits and linear depressions and extend for many 100 s of km downslope. Mapping the proximal to distal morphology of the complete channel and determining its relationship with other features on the apron provides evidence for the processes of formation and thei...
Introduction: Observations of migrating sand ripples and dunes on Mars [1] show that aeolian proc... more Introduction: Observations of migrating sand ripples and dunes on Mars [1] show that aeolian processes continue to shape the surface of the planet. Transverse aeolian ridges (TARs) are a unique class of stable aeolian bedform with a wide variety of morphologies [e.g., 2] and an unknown particle size distribution. Rover observations on the surface of Mars can provide insight into their local characteristics [3], but the sedimentology of TARs is likely to vary between locations. Geissler et al. [4] hypothesized that martian TARs originate from indurated dust deposits. Because of their stability, morphology and formation mechanisms, a number of large wavelength and amplitude aeolian megaripples with granule to gravel-sized particles have been used as terrestrial analogs for martian TARs [e.g., 5]. The Lut Desert of Iran, containing megaripples composed of 3–4 mm sized grains, has also emerged as a site of martian morphological comparisons [6, 7].
ABSTRACT The fracture patterns of lava flows exhibit unique structure associated with emplacement... more ABSTRACT The fracture patterns of lava flows exhibit unique structure associated with emplacement, shown here from high-resolution 3D models generated from field photos.
Wetlands, 2011
Sediment pollution is one of the most important contributors to the degradation of the Chesapeake... more Sediment pollution is one of the most important contributors to the degradation of the Chesapeake Bay. The Susquehanna River is one of the main sources of sediment to the Bay and this source could dramatically increase in the future. The reservoirs on the Susquehanna River are almost at sediment-storage capacity. The lowest reservoir (Conowingo) could be at capacity within a few decades (Langland and Hainly 1997). Once this occurs little sediment will be trapped and prevented from entering the Bay. Sediment continues to be supplied to the river system from across the watershed. Understanding the sources of this sediment, as well as the processes contributing to the continued flow of sediment, are crucial if efforts to restore the Bay's ecosystem are to be successful. Our study has focused on one of the sub-basins of the Susquehanna River located in Lancaster County, Pennsylvania. We have examined the spatial and temporal distribution of sediment in the stream channel and floodplain and linked this information to changes in the landscape over the last several thousand years. Typically we see coarse-grained channel lag deposits formed by lateral migration of streams which are overlain by predominately fine-grained organic-rich (including large logs) sediment that accumulated slowly over several thousand years (based on radiocarbon ages). Deforestation resulting from European occupation beginning in the early 1700's caused a significant increase in the rate of sediment deposition in the floodplain and a decrease in the organic content of the sediment. Debris flows from the surrounding hillslopes resulted in matrix-supported conglomerates within the floodplain sediments. Modifications to the stream channels to facilitate agriculture were also common. More recent landscape changes resulting from suburbanization have resulted in complex spatial and temporal responses in the stream system. Initially, sediment deposition in the channels increased, however changes in land development practices have resulted in increased peak stream flows and the remobilization of the sediment from the stream channels, streambanks, and B. A. LePage (ed.