Geology topics
Page C. Valentine
Publications and source records attributed to Page C. Valentine.
Sea floor topography of the Stellwagen Bank National Marine Sanctuary off Boston, Massachusetts
No abstract available.
Sun-illuminated sea floor topography of the Stellwagen Bank National Marine Sanctuary off Boston, Massachusetts
No abstract available.
Backscatter intensity and sun-illuminated sea floor topography of the Stellwagen Bank National Marine Sanctuary off Boston, Massachusetts
No abstract available.
Shaded relief and sea floor topography of Quadrangle 2 in western Massachusetts Bay offshore of Boston, Massachusetts
No abstract available.
Mapping the seabed and habitats in National Marine Sanctuaries - Examples from the East, Gulf and West Coasts
The National Marine Sanctuary System requires seabed and habitat maps to serve as a basis for managing sanctuary resources and for conducting research. NOAA, the agency that manages the sanctuaries, and the USGS have conducted mapping projects in three sanctuaries (Stellwagen Bank NMS, Flower Garden Banks NMS, and Channel Islands NMS) with an emphasis on collaboration of geologists and biologists from the two agencies and from academic institutions. Mapping of seabed habitats is a developing field that requires the integration of geologic and biologic studies and the use of swath imaging techniques such as multibeam and sidescan sonar. Major products of swath mapping are shaded-relief topographic imagery which shows seabed features in great detail, and backscatter imagery which provides an indication of the types of materials that constitute the seabed. Sea floor images provide an excellent basis for conducting the groundtruthing studies (using video, photo, and sampling techniques) that are required to collect the data necessary for making meaningful interpretative maps of the seabed. The compilation of interpretive maps showing seabed environments and habitats also requires the development of a sea floor classification system that will be a basis for comparing, managing, and researching characteristic areas of the seabed. Seabed maps of the sanctuaries are proving useful for management and research decisions that address commercial and recreational fishing, habitat disturbance, engineering projects, tourism, and cultural resources.
Maps Showing Sea Floor Topography, Sun-Illuminated Sea Floor Topography, and Backscatter Intensity of Quadrangles 1 and 2 in the Great South Channel Region, Western Georges Bank
The Great South Channel separates the western part of Georges Bank from Nantucket Shoals and is a major conduit for the exchange of water between the Gulf of Maine to the north and the Atlantic Ocean to the south. Water depths range mostly between 65 and 80 m in the region. A minimum depth of 45 m occurs in the east-central part of the mapped area, and a maximum depth of 100 m occurs in the northwest corner. The channel region is characterized by strong tidal and storm currents that flow dominantly north and south. Major topographic features of the seabed were formed by glacial and postglacial processes. Ice containing rock debris moved from north to south, sculpting the region into a broad shallow depression and depositing sediment to form the irregular depressions and low gravelly mounds and ridges that are visible in parts of the mapped area. Many other smaller glacial featuresprobably have been eroded by waves and currents at worksince the time when the region, formerly exposed bylowered sea level or occupied by ice, was invaded by the sea. The low, irregular and somewhat lumpy fabric formed by the glacial deposits is obscured in places by drifting sand and by the linear, sharp fabric formed by modern sand features. Today, sand transported by the strong north-south-flowing tidal and storm currents has formed large, east-west-trending dunes. These bedforms (ranging between 5 and 20 m in height) contrast strongly with, and partly mask, the subdued topography of the older glacial features.
Sea-Floor Topography of Quadrangle 1 in the Great South Channel, Western Georges Bank
The Great South Channel separates the western part of Georges Bank from Nantucket Shoals and is a major conduit for the exchange of water between the Gulf of Maine to the north and the Atlantic Ocean to the south. Water depths range mostly between 65 and 80 m in the region. A minimum depth of 45 m occurs in the east-central part of the mapped area, and a maximum depth of 100 m occurs in the northwest corner. The channel region is characterized by strong tidal and storm currents that flow dominantly north and south. Major topographic features of the seabed were formed by glacial and postglacial processes. Ice containing rock debris moved from north to south, sculpting the region into a broad shallow depression and depositing sediment to form the irregular depressions and low gravelly mounds and ridges that are visible in parts of the mapped area. Many other smaller glacial featuresprobably have been eroded by waves and currents at worksince the time when the region, formerly exposed bylowered sea level or occupied by ice, was invaded by the sea. The low, irregular and somewhat lumpy fabric formed by the glacial deposits is obscured in places by drifting sand and by the linear, sharp fabric formed by modern sand features. Today, sand transported by the strong north-south-flowing tidal and storm currents has formed large, east-west-trending dunes. These bedforms (ranging between 5 and 20 m in height) contrast strongly with, and partly mask, the subdued topography of the older glacial features.
Sun-Illuminated Sea Floor Topography of Quadrangle 1 in the Great South Channel, Western Georges Bank
The Great South Channel separates the western part of Georges Bank from Nantucket Shoals and is a major conduit for the exchange of water between the Gulf of Maine to the north and the Atlantic Ocean to the south. Water depths range mostly between 65 and 80 m in the region. A minimum depth of 45 m occurs in the east-central part of the mapped area, and a maximum depth of 100 m occurs in the northwest corner. The channel region is characterized by strong tidal and storm currents that flow dominantly north and south. Major topographic features of the seabed were formed by glacial and postglacial processes. Ice containing rock debris moved from north to south, sculpting the region into a broad shallow depression and depositing sediment to form the irregular depressions and low gravelly mounds and ridges that are visible in parts of the mapped area. Many other smaller glacial featuresprobably have been eroded by waves and currents at worksince the time when the region, formerly exposed bylowered sea level or occupied by ice, was invaded by the sea. The low, irregular and somewhat lumpy fabric formed by the glacial deposits is obscured in places by drifting sand and by the linear, sharp fabric formed by modern sand features. Today, sand transported by the strong north-south-flowing tidal and storm currents has formed large, east-west-trending dunes. These bedforms (ranging between 5 and 20 m in height) contrast strongly with, and partly mask, the subdued topography of the older glacial features.
Sea-Floor Topography of Quadrangle 2 in the Great South Channel, Western Georges Bank
The Great South Channel separates the western part of Georges Bank from Nantucket Shoals and is a major conduit for the exchange of water between the Gulf of Maine to the north and the Atlantic Ocean to the south. Water depths range mostly between 65 and 80 m in the region. A minimum depth of 45 m occurs in the east-central part of the mapped area, and a maximum depth of 100 m occurs in the northwest corner. The channel region is characterized by strong tidal and storm currents that flow dominantly north and south. Major topographic features of the seabed were formed by glacial and postglacial processes. Ice containing rock debris moved from north to south, sculpting the region into a broad shallow depression and depositing sediment to form the irregular depressions and low gravelly mounds and ridges that are visible in parts of the mapped area. Many other smaller glacial featuresprobably have been eroded by waves and currents at worksince the time when the region, formerly exposed bylowered sea level or occupied by ice, was invaded by the sea. The low, irregular and somewhat lumpy fabric formed by the glacial deposits is obscured in places by drifting sand and by the linear, sharp fabric formed by modern sand features. Today, sand transported by the strong north-south-flowing tidal and storm currents has formed large, east-west-trending dunes. These bedforms (ranging between 5 and 20 m in height) contrast strongly with, and partly mask, the subdued topography of the older glacial features.
Sun-Illuminated Sea Floor Topography of Quadrangle 2 in the Great South Channel, Western Georges Bank
The Great South Channel separates the western part of Georges Bank from Nantucket Shoals and is a major conduit for the exchange of water between the Gulf of Maine to the north and the Atlantic Ocean to the south. Water depths range mostly between 65 and 80 m in the region. A minimum depth of 45 m occurs in the east-central part of the mapped area, and a maximum depth of 100 m occurs in the northwest corner. The channel region is characterized by strong tidal and storm currents that flow dominantly north and south. Major topographic features of the seabed were formed by glacial and postglacial processes. Ice containing rock debris moved from north to south, sculpting the region into a broad shallow depression and depositing sediment to form the irregular depressions and low gravelly mounds and ridges that are visible in parts of the mapped area. Many other smaller glacial featuresprobably have been eroded by waves and currents at worksince the time when the region, formerly exposed bylowered sea level or occupied by ice, was invaded by the sea. The low, irregular and somewhat lumpy fabric formed by the glacial deposits is obscured in places by drifting sand and by the linear, sharp fabric formed by modern sand features. Today, sand transported by the strong north-south-flowing tidal and storm currents has formed large, east-west-trending dunes. These bedforms (ranging between 5 and 20 m in height) contrast strongly with, and partly mask, the subdued topography of the older glacial features.
Backscatter Intensity and Sun-Illuminated Sea Floor Topography of Quadrangles 1 and 2
The Great South Channel separates the western part of Georges Bank from Nantucket Shoals and is a major conduit for the exchange of water between the Gulf of Maine to the north and the Atlantic Ocean to the south. Water depths range mostly between 65 and 80 m in the region. A minimum depth of 45 m occurs in the east-central part of the mapped area, and a maximum depth of 100 m occurs in the northwest corner. The channel region is characterized by strong tidal and storm currents that flow dominantly north and south. Major topographic features of the seabed were formed by glacial and postglacial processes. Ice containing rock debris moved from north to south, sculpting the region into a broad shallow depression and depositing sediment to form the irregular depressions and low gravelly mounds and ridges that are visible in parts of the mapped area. Many other smaller glacial featuresprobably have been eroded by waves and currents at worksince the time when the region, formerly exposed bylowered sea level or occupied by ice, was invaded by the sea. The low, irregular and somewhat lumpy fabric formed by the glacial deposits is obscured in places by drifting sand and by the linear, sharp fabric formed by modern sand features. Today, sand transported by the strong north-south-flowing tidal and storm currents has formed large, east-west-trending dunes. These bedforms (ranging between 5 and 20 m in height) contrast strongly with, and partly mask, the subdued topography of the older glacial features.
Fish species and community distributions as proxies for sea-floor habitat distributions: the Stellwagen Bank National Marine Sanctuary example (northwest Atlantic, Gulf Of Maine)
Defining the habitats of fishes and associated fauna on outer continental shelves is problematic given the paucity of data on the actual types and distributions of seafloor habitats. However many regions have good data on the distributions of fishes from resource surveys or catch statistics because of the economic importance of the fisheries. Fish distribution data (species or communities) have been used as a proxy for the distribution of habitats to develop precautionary conservation strategies for habitat protection (e.g., marine protected areas, fishing gear restrictions). In this study we assessed the relationships between the distributions of fish communities and species derived from trawl survey data with the spatial distribution of sediment types determined by sampling and acoustic reflectance derived from multibeam sonar surveys in Stellwagen Bank National Marine Sanctuary. Fish communities were correlated with reflectance values but all communities did not occur in unique sediment types. This suggests that use of community distributions as proxies for habitats should include the caveat that a greater number of communities within an area could indicate a greater range of habitat types. Single species distributions showed relationships between abundance and reflectance values. Trawl catches with low abundances had wide variations in reflectance values while those with high abundances had narrower ranges indicating habitat affinities. Significant non-random frequency-dependent relationships were observed for 17 of 20 species although only 12 of 20 species had significant relationships based on rank correlation. These results suggest that species distributions based on trawl survey data can be used as proxies for the distribution of seafloor habitats. Species with known habitat associations can be used to infer habitat requirements of co-occurring species and can be used to identify a range of habitat types.