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Filters: Tags: Limestone (X) > Categories: Data (X) > partyWithName: U.S. Geological Survey (X)

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This part of the release provides an updated georeferenced catalog of limestone boulders and cobbles pertaining to extreme waves on Anegada, a low Caribbean island perched south of the Puerto Rico Trench. Tabulated are 660 limestone clasts, along with clast dimensions and long-axis trend in many instances. Fewer than one-fifth of the clasts were reported previously in https://doi.org/10.1007/s11069-011-9725-8 and https://doi.org/10.1130/GES01356.1. Most were surveyed in 2017.
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This part of the data release aids in identifying places where land-clearing and wall-building, rather than a sea flood, may account for anomalous boulders and cobbles of Pleistocene limestone on Anegada. The wall shapefile delineates much of a network of walls found mainly on the east half of the island. It can be plotted in GIS with the shapefile of limestone clasts, most of which form boulder fields that trail southward from limestone knolls, promontories, and other outcrops. The comparison shows that these clast fields are most abundant on low ground in and near salt ponds, while the walls run mostly on higher ground.
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May sea floods contaminate Anegada groundwater by entering a freshwater aquifer through sink holes? Groundwater provides the island's main naturally available source of freshwater. Robert Schomburgk in 1832 reported natural wells provided by holes in limestone (https://library.iucn-isg.org/documents/1832/Schomburgk_1832_The_Journal_of_the_Royal_Geographical_Society_of_London.pdf). Today, sinks in the limestone are readily mapped today in lidar topography. The dataset here identifies 1,508 closed topographic depressions. Several holding water were examined during field work in 2008–2017. The water level in them was close to mean sea level, as estimated from differences between lidar elevations of rims and depths...
    map background search result map search result map Limestone boulders and cobbles noted 2009 to 2017 that pertain to sea floods of the past 1,000 years on Anegada, British Virgin Islands Closed depressions in 2014 lidar topography in areas of Pleistocene limestone on Anegada, British Virgin Islands Rock walls mapped from 2002 airphotos and 2014 lidar topography of Anegada, British Virgin Islands Rock walls mapped from 2002 airphotos and 2014 lidar topography of Anegada, British Virgin Islands Closed depressions in 2014 lidar topography in areas of Pleistocene limestone on Anegada, British Virgin Islands Limestone boulders and cobbles noted 2009 to 2017 that pertain to sea floods of the past 1,000 years on Anegada, British Virgin Islands