Thomas Jorstad - Academia.edu (original) (raw)

Papers by Thomas Jorstad

Research paper thumbnail of Underwater archaeology in the Canopic region in Egypt, Geoarchaeology

Research paper thumbnail of Iron-Stained Quartz as Record of Recent Reworking of Older Sediment by Natural and Anthropogenic Processes, Rio Grande Delta, Texas

Journal of Coastal Research, Jul 27, 2001

The iron-coated quartz grain record in the Rio Grande deltaic plain in southern Texas, determined... more The iron-coated quartz grain record in the Rio Grande deltaic plain in southern Texas, determined from petrologic study of surface and core samples, does not show the distribution pattern typically observed in other deltas. The ironstained grain distribution patterns in this delta are highly irregular in both time and space, and do not display low proportions « 10%)) of coated grains in surficial and Holocene subsurface deltaic sections versus distinctly higher proportions (to over >20%)) of stained grains in underlying Pleistocene alluvial strata. Intermediate (> 10%) to large (>20%)) amounts of partially plus fully coated quartz particles are measured in most surficial samples of 10 sampled deltaic depositional environments and in Holocene core sections. This is a result of (1) pre-dam fluvial transport of older, iron-stained material from Rio Grande basin areas to the Holocene cover of the delta and its Gulf of Mexico margin, (2) erosion and recent reworking landward of iron-stained sediment from Rio Grande delta terrains now submerged on the inner and mid-shelf, (3) possible in situ formation of iron-coated grains in the lower valley and delta proper, and (4) intensified post-depositional reworking of the deltaic plain and upper Holocene sections by human activity during the past century. We suggest that anthropogenic activity has now replaced natural processes, especially fluvial transport, as the primary means of mixing older material onto the younger surficial Rio Grande deltaic plain. The delta's present sediment cover is interpreted as a 'palimpsest' comprising admixtures of reworked modern and relict material, particularly in areas where formerly buried sediment continues to be artificially exposed and modified. We anticipate that the proportion of iron-coated grains will remain high at the Rio Grande deltaic surface as human activity continues to replace natural fluvial transport as the dominant process.

Research paper thumbnail of Iron-Stained Quartz to Distinguish Holocene Deltaic from Pleistocene Alluvial Deposits in Small Core Samples

Journal of Coastal Research, Apr 28, 2000

The recorded proportions of three sand-size quartz grain types-clear, partially stained and fully... more The recorded proportions of three sand-size quartz grain types-clear, partially stained and fully stained-are used to distinguish Holocene from Pleistocene sediment in small core cuttings and washings of borings recovered in the Nile and Ganges-Brahmaputra deltas. To verify the general applicability of the method, we selected for study 343 samples from 13 cores in these two deltas that formed in markedly different geographic and climatic settings: the Nile delta in the highly arid and warm to hot region of Egypt; and, in contrast, the Ganges-Brahmaputra delta in the humid hot region of India and Bangladesh. Analyses indicate that pigments are composed of iron oxides, likely including goethite. Samples of late Pleistocene alluvial sediment show consistently higher proportions of both partially and fully coated quartz types than in the overlying Holocene deltaic deposits. This finding prevails regardless of factors such as sediment process, transport distance, lithology of sediment section examined, and sand grain texture. On the basis of actual measurements made in the present investigation, it appears possible to recognize Holocene and Pleistocene strata by counting the 3 sand-sized quartz grain types (325-350 grains/sample) in as few as 10 to 20 small samples that are distributed downcore in a minimum of 3 to 6 borings. The method is simple, rapid, inexpensive, and particularly well suited for stratigraphic interpretation of sediment sections that are incomplete and/or poorly dated.

Research paper thumbnail of Pelusium, an Ancient Port Fortress on Egypt's Nile Delta Coast: Its Evolving Environmental Setting from Foundation to Demise

Journal of Coastal Research, Mar 1, 2008

... Jean-Daniel Stanley a , Maria Pia Bernasconi b , and Thomas F. Jorstad a ... of sites on the ... more ... Jean-Daniel Stanley a , Maria Pia Bernasconi b , and Thomas F. Jorstad a ... of sites on the lower delta plain, east of the Suez Canal and at, and north of, the latitude of Pelusium (Figure 1), have recorded no archaeological sites older than Roman (Moshier and el-Kalani, 2008). ...

Research paper thumbnail of Short contribution: Buried Canopic channel identified near Egypt's Nile delta coast with radar (SRTM) imagery

Geoarchaeology-an International Journal, 2006

Shuttle Radar Topography Mission (SRTM) data, with ground-based geologic investigations, define t... more Shuttle Radar Topography Mission (SRTM) data, with ground-based geologic investigations, define the geographic position of the relict Canopic channel in Egypt's NW Nile delta. Two sinuous channel segments south of Abu Qir Bay are observed on a radar image: a more sinuous trace (36 km in length) west of Idku lagoon, and an eastern one (~20 km), reaching the lagoon's southeast corner. Sediment cores recovered along channel traces show sand-rich deposits (to Ͼ 4 m thick) beneath the surface, in contrast with silty muds in areas away from channels. Historic and archaeological findings indicate that the Ptolemaic Roman city of Schedia once lay directly along the Canopic that channeled water from the 3rd to 2nd centuries B.C. until ~5th century A.D., after which Nile water was displaced to the east via Bolbitic and, later, Rosetta branches. Identification of buried, but well-defined, Canopic channels provides baselines for renewed archaeological exploration in this delta sector.

Research paper thumbnail of Alexandria, Egypt, before Alexander the Great: A multidisciplinary approach yields rich discoveries

GSA today, 2007

Historic records refer to Rhakotis as a settlement on Egypt's Mediterranean coast before Alexande... more Historic records refer to Rhakotis as a settlement on Egypt's Mediterranean coast before Alexander the Great founded the famous Mediterranean port city of Alexandria in B.C. 332. Little is known of Rhakotis, however, because the site has yet to be clearly identified beneath the modern city. This problem motivated a geoarchaeological investigation of sediment cores from Alexandria's East Harbor, from which radiocarbon-dated sections of pre-Alexander age (>2300 yr B.P.) have been obtained for study. These core sections comprise a number of critical components, five of which are emphasized here: ceramics, rock fragments derived from Middle and Upper Egypt, and sediment with markedly increased contents of lead, heavy minerals, and organic matter. A multidisciplinary approach, by which archaeological, stratigraphical, petrological, and geochemical methodologies are applied to study the five distinct core components, reaffirms that a sum can be greater than its parts. Together, the diverse markers in the dated core sections enable us to confirm human activity to at least seven centuries before B.C. 332 on the mainland coast, where Alexandria would later be established. Alexander's city, it now appears, rose from a preexisting town whose inhabitants had long before recognized the favorable harbor potential of this Egyptian coastal sector. The discoveries, providing direct evidence of the settlement's early (to ca. B.C. 1000) existence, are intended to prompt new exploratory efforts on land and offshore to further delineate that center's actual position and history.

Research paper thumbnail of Buried Canopic Channel Identified Near Egypt's Nile Delta Coast with Radar (SRTM) Imagery

Research paper thumbnail of Iron-Coated Quartz as a Provenance and Paleoclimatic Marker in the Rhone Delta, France

Journal of Coastal Research, Oct 11, 2002

Analyses of 430 surficial and core sediment samples in the Rhone delta and adjacent region in sou... more Analyses of 430 surficial and core sediment samples in the Rhone delta and adjacent region in southern France record similar average proportions of iron-stained quartz (lSQ) on the delta plain and in the Rhone and Durance rivers (~30%). These two rivers, largely responsible for the formation of the Holocene delta, carried most of their sediment load from distal source terrains. The much higher ISQ values in sand on the delta's modern coast (to >40'1<) and on older sand strand deposits (56';') subaerially exposed in the central and southern delta plain are primarily the result of post-depositional in situ formation of iron coating on quartz particles. However, some subsurface delta plain core samples with high stained-grain content (>40%) have a different origin. These layers were derived from Pleistocene and older sediment in proximal terrains, characterized by very high ISQ values (67%), that were transported to the delta plain. Evidence indicating displacement of highly-stained material eroded from these more local source areas is quartz with high ISQ values (50%) in the Vidourle and Gardon rivers with headwaters in adjacent uplands. Strata with large ISQ values (>40%) in Holocene core sections are attributed primarily to periodically increased hydrological fluxes that resulted from marked paleoclimatic changes and, possibly, effects of human activity as seen in the archaeological record in southern France. Wetter climatic conditions increased the erosion and reworking of proximal ISQ-enriched terrigenous sediment to the delta. This study indicates that the stained-grain methodcan be used to help identify changes in sediment provenance and dispersal patterns related to Holocene paleoclimatic fluctuations and/or human activity in the Rhone delta region.

Research paper thumbnail of Archaeological and Geom0Rphic Testing at Four Sites in the Sevier Desert and Canyon Mountains, Western Utah

Research paper thumbnail of Direct Sediment Dispersal from Mountain to Shore, with Bypassing via Three Human-Modified Channel Systems to Lake Annecy, SE France

Journal of Coastal Research, Sep 1, 2004

Research paper thumbnail of Preliminary Archaeological and Geological Analyses At the Antelope Quarry Site 32MZ330 McKenzie County, North Dakota

Archaeology in Montana, 1987

Research paper thumbnail of Phase I / Phase II Archaeological Examination of a Texas Eastern Gas Pipeline Right-Of-Way in Somerset and Milford Townships, Somerset County, Pennsylvania

Research paper thumbnail of Archaeological Investigations On the Solid Waste Disposal Area, Wm. H. Zimmer Generating Station, Clermont County, Ohio

Research paper thumbnail of Underwater archaeology in the Canopic region in Egypt, Geoarchaeology

Research paper thumbnail of Predynastic human presence discovered by core drilling at the northern Nile delta coast, Egypt

Research paper thumbnail of Iron-stained quartz as record of recent reworking of older sediment by natural and anthropogenic processes, Rio Grande delta, Texas

The iron-coated quartz grain record in the Rio Grande deltaic plain in southern Texas, determined... more The iron-coated quartz grain record in the Rio Grande deltaic plain in southern Texas, determined from petrologic study of surface and core samples, does not show the distribution pattern typically observed in other deltas. The ironstained grain distribution patterns in this delta are highly irregular in both time and space, and do not display low proportions « 10%)) of coated grains in surficial and Holocene subsurface deltaic sections versus distinctly higher proportions (to over >20%)) of stained grains in underlying Pleistocene alluvial strata. Intermediate (> 10%) to large (>20%)) amounts of partially plus fully coated quartz particles are measured in most surficial samples of 10 sampled deltaic depositional environments and in Holocene core sections. This is a result of (1) pre-dam fluvial transport of older, iron-stained material from Rio Grande basin areas to the Holocene cover of the delta and its Gulf of Mexico margin, (2) erosion and recent reworking landward of iron-stained sediment from Rio Grande delta terrains now submerged on the inner and mid-shelf, (3) possible in situ formation of iron-coated grains in the lower valley and delta proper, and (4) intensified post-depositional reworking of the deltaic plain and upper Holocene sections by human activity during the past century. We suggest that anthropogenic activity has now replaced natural processes, especially fluvial transport, as the primary means of mixing older material onto the younger surficial Rio Grande deltaic plain. The delta's present sediment cover is interpreted as a 'palimpsest' comprising admixtures of reworked modern and relict material, particularly in areas where formerly buried sediment continues to be artificially exposed and modified. We anticipate that the proportion of iron-coated grains will remain high at the Rio Grande deltaic surface as human activity continues to replace natural fluvial transport as the dominant process.

Research paper thumbnail of Human impact on sediment mass movement and submergence of ancient siles in the two harbours of Alexandria, Egypt

Historic records indicate that structures built in and around the two harbours of Alexandria, Egy... more Historic records indicate that structures built in and around the two harbours of Alexandria, Egypt, were periodically damaged by powerful events such as earthquakes and tsunamis. This geoarchaeological study reveals that human activity in nearshore and port settings has also triggered sediment deformation and construction failure. Analysis of radiocarbon-dated Holocene cores and submerged archaeological excavations record a significant incidence of sediment destabilization and mass movement in the ports since human occupation in the 1 st millennium B.C. Anthropogenic substrate failure is documented from about the time of the city's founding by the Greeks in the 4 th century B.C. to the present. Construction on unconsolidated sediment substrates was a factor of sediment destabilization, at times in conjunction with earthquakes, storm waves and tsunamis. Engineer reports on port construction during the past century, however, show substrate failure can also occur by building and other human activity, independently of high-energy natural events. Some recent failure and associated mass flows in the harbours were triggered by loading effects associated with emplacement of large structures on weak, water-saturated substrates. Slumps, debris flows and mudflows, initiated by substrate destabilization, caused lateral displacement of sediment and construction debris for tens of meters away from construction sites. Human-induced processes that triggered sediment failure in the ports from Greek to recent time are not likely to be unique to this sector, and findings here may help explain how some sites in coastal settings elsewhere were submerged.

Research paper thumbnail of Iron-stained quartz to distinguish Holocene deltaic from Pleistocene alluvial deposits in small core samples

Research paper thumbnail of Iron-Coated Quartz as a Provenance and Paleoclimatic Marker in the Rhône Delta, France

Analyses of 430 surficial and core sediment samples in the Rhone delta and adjacent region in sou... more Analyses of 430 surficial and core sediment samples in the Rhone delta and adjacent region in southern France record similar average proportions of iron-stained quartz (ISQ) on the delta plain and in the Rhone and Durance rivers (-30%). These two rivers, largely responsible for the formation of the Holocene delta, carried most of their sediment load from distal source terrains. The much higher ISQ values in sand on the delta's modern coast (to >407r) and on older sand strand deposits (569;) subaerially exposed in the central and southern delta plain are primarily the result of post-depositional in situ formation of iron coating on quartz particles. However, .some subsurface delta plain core samples with high stained-gram content (>409c) have a different origin. These layers were derived from Pleistocene and older sediment in proximal terrains, characterized by very high ISQ values (679^), that were transported to the delta plain. Evidence indicating displacement of highly-stained material eroded from these more local .source areas is quartz with high ISQ values (50%) in the Vidourle and Garden rivers with headwaters in adjacent uplands. Strata with large ISQ values (>40%) in Holocene core sections are attributed primarily to periodically increased hydrological fluxes that resulted from marked paleoclimatic changes and, possibly, effects of human activity as seen in the archaeological record in southern France. Wetter climatic conditions increased the erosion and reworking of proximal ISQ-enriched terrigenous sediment to the delta. This study indicates that the stained-grain method can be used to help identify changes in sediment provenance and dispersal patterns related to Holocene paleoclimatic fluctuations and/or human activity in the Rhone delta region.

Research paper thumbnail of Earliest art in the Americas: incised image of a proboscidean on a mineralized extinct animal bone from Vero Beach, Florida

Journal of Archaeological Science, 2011

A fragmented fossil bone incised with the figure of a proboscidean was recently found at Vero Bea... more A fragmented fossil bone incised with the figure of a proboscidean was recently found at Vero Beach, Florida near the location where Late Pleistocene fauna and human bones were recovered from 1913-1916. This engraving may represent the oldest and only existing example of Terminal Pleistocene art depicting a proboscidean in the Americas. Because of the uniqueness, rarity, and potential antiquity of this specimen, caution demanded that a variety of tests be used in an attempt to verify its authenticity. The mineralized bone was identified as mammoth, mastodon, or giant sloth. Rare earth element analysis was consistent with the fossil bone being ancient and originating at or near the Old Vero site (8-IR-9). Forensic analysis suggests the markings on the bone are not recent. Optical microscopy results show no discontinuity in coloration between the carved grooves and the surrounding material indicating that both surfaces aged simultaneously. Scanning electron microscopy (SEM) revealed that the edges of the inscription are worn and show no signs of being incised recently or that the grooves were made with metal tools. In addition, the backscattered SEM images suggest there is no discontinuity in the distribution of light and heavy elements between the scribed region and the surrounding bone indicating that both surfaces aged in the same environment. This is very different from an intentional mark made on the bone for comparison. Energy dispersive x-ray spectroscopy (EDXS) shows that the surface contains significant amounts of calcium, phosphorus, oxygen, and carbon typical of a mineralized bone surface. Examination of a cast and mold of the incised bone by Reflectance Transformation Imaging (RTI) also provided no evidence that the engraving was made recently. All of these results are consistent with the mammoth engraving being authentic.

Research paper thumbnail of Underwater archaeology in the Canopic region in Egypt, Geoarchaeology

Research paper thumbnail of Iron-Stained Quartz as Record of Recent Reworking of Older Sediment by Natural and Anthropogenic Processes, Rio Grande Delta, Texas

Journal of Coastal Research, Jul 27, 2001

The iron-coated quartz grain record in the Rio Grande deltaic plain in southern Texas, determined... more The iron-coated quartz grain record in the Rio Grande deltaic plain in southern Texas, determined from petrologic study of surface and core samples, does not show the distribution pattern typically observed in other deltas. The ironstained grain distribution patterns in this delta are highly irregular in both time and space, and do not display low proportions « 10%)) of coated grains in surficial and Holocene subsurface deltaic sections versus distinctly higher proportions (to over >20%)) of stained grains in underlying Pleistocene alluvial strata. Intermediate (> 10%) to large (>20%)) amounts of partially plus fully coated quartz particles are measured in most surficial samples of 10 sampled deltaic depositional environments and in Holocene core sections. This is a result of (1) pre-dam fluvial transport of older, iron-stained material from Rio Grande basin areas to the Holocene cover of the delta and its Gulf of Mexico margin, (2) erosion and recent reworking landward of iron-stained sediment from Rio Grande delta terrains now submerged on the inner and mid-shelf, (3) possible in situ formation of iron-coated grains in the lower valley and delta proper, and (4) intensified post-depositional reworking of the deltaic plain and upper Holocene sections by human activity during the past century. We suggest that anthropogenic activity has now replaced natural processes, especially fluvial transport, as the primary means of mixing older material onto the younger surficial Rio Grande deltaic plain. The delta's present sediment cover is interpreted as a 'palimpsest' comprising admixtures of reworked modern and relict material, particularly in areas where formerly buried sediment continues to be artificially exposed and modified. We anticipate that the proportion of iron-coated grains will remain high at the Rio Grande deltaic surface as human activity continues to replace natural fluvial transport as the dominant process.

Research paper thumbnail of Iron-Stained Quartz to Distinguish Holocene Deltaic from Pleistocene Alluvial Deposits in Small Core Samples

Journal of Coastal Research, Apr 28, 2000

The recorded proportions of three sand-size quartz grain types-clear, partially stained and fully... more The recorded proportions of three sand-size quartz grain types-clear, partially stained and fully stained-are used to distinguish Holocene from Pleistocene sediment in small core cuttings and washings of borings recovered in the Nile and Ganges-Brahmaputra deltas. To verify the general applicability of the method, we selected for study 343 samples from 13 cores in these two deltas that formed in markedly different geographic and climatic settings: the Nile delta in the highly arid and warm to hot region of Egypt; and, in contrast, the Ganges-Brahmaputra delta in the humid hot region of India and Bangladesh. Analyses indicate that pigments are composed of iron oxides, likely including goethite. Samples of late Pleistocene alluvial sediment show consistently higher proportions of both partially and fully coated quartz types than in the overlying Holocene deltaic deposits. This finding prevails regardless of factors such as sediment process, transport distance, lithology of sediment section examined, and sand grain texture. On the basis of actual measurements made in the present investigation, it appears possible to recognize Holocene and Pleistocene strata by counting the 3 sand-sized quartz grain types (325-350 grains/sample) in as few as 10 to 20 small samples that are distributed downcore in a minimum of 3 to 6 borings. The method is simple, rapid, inexpensive, and particularly well suited for stratigraphic interpretation of sediment sections that are incomplete and/or poorly dated.

Research paper thumbnail of Pelusium, an Ancient Port Fortress on Egypt's Nile Delta Coast: Its Evolving Environmental Setting from Foundation to Demise

Journal of Coastal Research, Mar 1, 2008

... Jean-Daniel Stanley a , Maria Pia Bernasconi b , and Thomas F. Jorstad a ... of sites on the ... more ... Jean-Daniel Stanley a , Maria Pia Bernasconi b , and Thomas F. Jorstad a ... of sites on the lower delta plain, east of the Suez Canal and at, and north of, the latitude of Pelusium (Figure 1), have recorded no archaeological sites older than Roman (Moshier and el-Kalani, 2008). ...

Research paper thumbnail of Short contribution: Buried Canopic channel identified near Egypt's Nile delta coast with radar (SRTM) imagery

Geoarchaeology-an International Journal, 2006

Shuttle Radar Topography Mission (SRTM) data, with ground-based geologic investigations, define t... more Shuttle Radar Topography Mission (SRTM) data, with ground-based geologic investigations, define the geographic position of the relict Canopic channel in Egypt's NW Nile delta. Two sinuous channel segments south of Abu Qir Bay are observed on a radar image: a more sinuous trace (36 km in length) west of Idku lagoon, and an eastern one (~20 km), reaching the lagoon's southeast corner. Sediment cores recovered along channel traces show sand-rich deposits (to Ͼ 4 m thick) beneath the surface, in contrast with silty muds in areas away from channels. Historic and archaeological findings indicate that the Ptolemaic Roman city of Schedia once lay directly along the Canopic that channeled water from the 3rd to 2nd centuries B.C. until ~5th century A.D., after which Nile water was displaced to the east via Bolbitic and, later, Rosetta branches. Identification of buried, but well-defined, Canopic channels provides baselines for renewed archaeological exploration in this delta sector.

Research paper thumbnail of Alexandria, Egypt, before Alexander the Great: A multidisciplinary approach yields rich discoveries

GSA today, 2007

Historic records refer to Rhakotis as a settlement on Egypt's Mediterranean coast before Alexande... more Historic records refer to Rhakotis as a settlement on Egypt's Mediterranean coast before Alexander the Great founded the famous Mediterranean port city of Alexandria in B.C. 332. Little is known of Rhakotis, however, because the site has yet to be clearly identified beneath the modern city. This problem motivated a geoarchaeological investigation of sediment cores from Alexandria's East Harbor, from which radiocarbon-dated sections of pre-Alexander age (>2300 yr B.P.) have been obtained for study. These core sections comprise a number of critical components, five of which are emphasized here: ceramics, rock fragments derived from Middle and Upper Egypt, and sediment with markedly increased contents of lead, heavy minerals, and organic matter. A multidisciplinary approach, by which archaeological, stratigraphical, petrological, and geochemical methodologies are applied to study the five distinct core components, reaffirms that a sum can be greater than its parts. Together, the diverse markers in the dated core sections enable us to confirm human activity to at least seven centuries before B.C. 332 on the mainland coast, where Alexandria would later be established. Alexander's city, it now appears, rose from a preexisting town whose inhabitants had long before recognized the favorable harbor potential of this Egyptian coastal sector. The discoveries, providing direct evidence of the settlement's early (to ca. B.C. 1000) existence, are intended to prompt new exploratory efforts on land and offshore to further delineate that center's actual position and history.

Research paper thumbnail of Buried Canopic Channel Identified Near Egypt's Nile Delta Coast with Radar (SRTM) Imagery

Research paper thumbnail of Iron-Coated Quartz as a Provenance and Paleoclimatic Marker in the Rhone Delta, France

Journal of Coastal Research, Oct 11, 2002

Analyses of 430 surficial and core sediment samples in the Rhone delta and adjacent region in sou... more Analyses of 430 surficial and core sediment samples in the Rhone delta and adjacent region in southern France record similar average proportions of iron-stained quartz (lSQ) on the delta plain and in the Rhone and Durance rivers (~30%). These two rivers, largely responsible for the formation of the Holocene delta, carried most of their sediment load from distal source terrains. The much higher ISQ values in sand on the delta's modern coast (to >40'1<) and on older sand strand deposits (56';') subaerially exposed in the central and southern delta plain are primarily the result of post-depositional in situ formation of iron coating on quartz particles. However, some subsurface delta plain core samples with high stained-grain content (>40%) have a different origin. These layers were derived from Pleistocene and older sediment in proximal terrains, characterized by very high ISQ values (67%), that were transported to the delta plain. Evidence indicating displacement of highly-stained material eroded from these more local source areas is quartz with high ISQ values (50%) in the Vidourle and Gardon rivers with headwaters in adjacent uplands. Strata with large ISQ values (>40%) in Holocene core sections are attributed primarily to periodically increased hydrological fluxes that resulted from marked paleoclimatic changes and, possibly, effects of human activity as seen in the archaeological record in southern France. Wetter climatic conditions increased the erosion and reworking of proximal ISQ-enriched terrigenous sediment to the delta. This study indicates that the stained-grain methodcan be used to help identify changes in sediment provenance and dispersal patterns related to Holocene paleoclimatic fluctuations and/or human activity in the Rhone delta region.

Research paper thumbnail of Archaeological and Geom0Rphic Testing at Four Sites in the Sevier Desert and Canyon Mountains, Western Utah

Research paper thumbnail of Direct Sediment Dispersal from Mountain to Shore, with Bypassing via Three Human-Modified Channel Systems to Lake Annecy, SE France

Journal of Coastal Research, Sep 1, 2004

Research paper thumbnail of Preliminary Archaeological and Geological Analyses At the Antelope Quarry Site 32MZ330 McKenzie County, North Dakota

Archaeology in Montana, 1987

Research paper thumbnail of Phase I / Phase II Archaeological Examination of a Texas Eastern Gas Pipeline Right-Of-Way in Somerset and Milford Townships, Somerset County, Pennsylvania

Research paper thumbnail of Archaeological Investigations On the Solid Waste Disposal Area, Wm. H. Zimmer Generating Station, Clermont County, Ohio

Research paper thumbnail of Underwater archaeology in the Canopic region in Egypt, Geoarchaeology

Research paper thumbnail of Predynastic human presence discovered by core drilling at the northern Nile delta coast, Egypt

Research paper thumbnail of Iron-stained quartz as record of recent reworking of older sediment by natural and anthropogenic processes, Rio Grande delta, Texas

The iron-coated quartz grain record in the Rio Grande deltaic plain in southern Texas, determined... more The iron-coated quartz grain record in the Rio Grande deltaic plain in southern Texas, determined from petrologic study of surface and core samples, does not show the distribution pattern typically observed in other deltas. The ironstained grain distribution patterns in this delta are highly irregular in both time and space, and do not display low proportions « 10%)) of coated grains in surficial and Holocene subsurface deltaic sections versus distinctly higher proportions (to over >20%)) of stained grains in underlying Pleistocene alluvial strata. Intermediate (> 10%) to large (>20%)) amounts of partially plus fully coated quartz particles are measured in most surficial samples of 10 sampled deltaic depositional environments and in Holocene core sections. This is a result of (1) pre-dam fluvial transport of older, iron-stained material from Rio Grande basin areas to the Holocene cover of the delta and its Gulf of Mexico margin, (2) erosion and recent reworking landward of iron-stained sediment from Rio Grande delta terrains now submerged on the inner and mid-shelf, (3) possible in situ formation of iron-coated grains in the lower valley and delta proper, and (4) intensified post-depositional reworking of the deltaic plain and upper Holocene sections by human activity during the past century. We suggest that anthropogenic activity has now replaced natural processes, especially fluvial transport, as the primary means of mixing older material onto the younger surficial Rio Grande deltaic plain. The delta's present sediment cover is interpreted as a 'palimpsest' comprising admixtures of reworked modern and relict material, particularly in areas where formerly buried sediment continues to be artificially exposed and modified. We anticipate that the proportion of iron-coated grains will remain high at the Rio Grande deltaic surface as human activity continues to replace natural fluvial transport as the dominant process.

Research paper thumbnail of Human impact on sediment mass movement and submergence of ancient siles in the two harbours of Alexandria, Egypt

Historic records indicate that structures built in and around the two harbours of Alexandria, Egy... more Historic records indicate that structures built in and around the two harbours of Alexandria, Egypt, were periodically damaged by powerful events such as earthquakes and tsunamis. This geoarchaeological study reveals that human activity in nearshore and port settings has also triggered sediment deformation and construction failure. Analysis of radiocarbon-dated Holocene cores and submerged archaeological excavations record a significant incidence of sediment destabilization and mass movement in the ports since human occupation in the 1 st millennium B.C. Anthropogenic substrate failure is documented from about the time of the city's founding by the Greeks in the 4 th century B.C. to the present. Construction on unconsolidated sediment substrates was a factor of sediment destabilization, at times in conjunction with earthquakes, storm waves and tsunamis. Engineer reports on port construction during the past century, however, show substrate failure can also occur by building and other human activity, independently of high-energy natural events. Some recent failure and associated mass flows in the harbours were triggered by loading effects associated with emplacement of large structures on weak, water-saturated substrates. Slumps, debris flows and mudflows, initiated by substrate destabilization, caused lateral displacement of sediment and construction debris for tens of meters away from construction sites. Human-induced processes that triggered sediment failure in the ports from Greek to recent time are not likely to be unique to this sector, and findings here may help explain how some sites in coastal settings elsewhere were submerged.

Research paper thumbnail of Iron-stained quartz to distinguish Holocene deltaic from Pleistocene alluvial deposits in small core samples

Research paper thumbnail of Iron-Coated Quartz as a Provenance and Paleoclimatic Marker in the Rhône Delta, France

Analyses of 430 surficial and core sediment samples in the Rhone delta and adjacent region in sou... more Analyses of 430 surficial and core sediment samples in the Rhone delta and adjacent region in southern France record similar average proportions of iron-stained quartz (ISQ) on the delta plain and in the Rhone and Durance rivers (-30%). These two rivers, largely responsible for the formation of the Holocene delta, carried most of their sediment load from distal source terrains. The much higher ISQ values in sand on the delta's modern coast (to >407r) and on older sand strand deposits (569;) subaerially exposed in the central and southern delta plain are primarily the result of post-depositional in situ formation of iron coating on quartz particles. However, .some subsurface delta plain core samples with high stained-gram content (>409c) have a different origin. These layers were derived from Pleistocene and older sediment in proximal terrains, characterized by very high ISQ values (679^), that were transported to the delta plain. Evidence indicating displacement of highly-stained material eroded from these more local .source areas is quartz with high ISQ values (50%) in the Vidourle and Garden rivers with headwaters in adjacent uplands. Strata with large ISQ values (>40%) in Holocene core sections are attributed primarily to periodically increased hydrological fluxes that resulted from marked paleoclimatic changes and, possibly, effects of human activity as seen in the archaeological record in southern France. Wetter climatic conditions increased the erosion and reworking of proximal ISQ-enriched terrigenous sediment to the delta. This study indicates that the stained-grain method can be used to help identify changes in sediment provenance and dispersal patterns related to Holocene paleoclimatic fluctuations and/or human activity in the Rhone delta region.

Research paper thumbnail of Earliest art in the Americas: incised image of a proboscidean on a mineralized extinct animal bone from Vero Beach, Florida

Journal of Archaeological Science, 2011

A fragmented fossil bone incised with the figure of a proboscidean was recently found at Vero Bea... more A fragmented fossil bone incised with the figure of a proboscidean was recently found at Vero Beach, Florida near the location where Late Pleistocene fauna and human bones were recovered from 1913-1916. This engraving may represent the oldest and only existing example of Terminal Pleistocene art depicting a proboscidean in the Americas. Because of the uniqueness, rarity, and potential antiquity of this specimen, caution demanded that a variety of tests be used in an attempt to verify its authenticity. The mineralized bone was identified as mammoth, mastodon, or giant sloth. Rare earth element analysis was consistent with the fossil bone being ancient and originating at or near the Old Vero site (8-IR-9). Forensic analysis suggests the markings on the bone are not recent. Optical microscopy results show no discontinuity in coloration between the carved grooves and the surrounding material indicating that both surfaces aged simultaneously. Scanning electron microscopy (SEM) revealed that the edges of the inscription are worn and show no signs of being incised recently or that the grooves were made with metal tools. In addition, the backscattered SEM images suggest there is no discontinuity in the distribution of light and heavy elements between the scribed region and the surrounding bone indicating that both surfaces aged in the same environment. This is very different from an intentional mark made on the bone for comparison. Energy dispersive x-ray spectroscopy (EDXS) shows that the surface contains significant amounts of calcium, phosphorus, oxygen, and carbon typical of a mineralized bone surface. Examination of a cast and mold of the incised bone by Reflectance Transformation Imaging (RTI) also provided no evidence that the engraving was made recently. All of these results are consistent with the mammoth engraving being authentic.