Danforth William W.
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PreprintCharacter and distribution of exposed glaciodeltaic deposits off outer Cape Cod, Massachusetts, and their effects on hydrogeology and benthic habitats( 2005-05-15) Poppe, Lawrence J. ; Foster, David S. ; Danforth, William W.Sea-bed outcrops of glaciodeltaic sediments were identified in four places east of Cape Cod, Massachusetts during seismic-reflection, multibeam bathymetric and backscatter, bottom photographic, and sediment sampling surveys. These strata record coarser-grained ice-proximal glaciofluvial topset to finer-grained distal glaciolacustrine bottomset deposition within deltaic systems that prograded southwestward into glacial lakes from the South Channel lobe about 18 ka B.P. These beds are important because they (1) influence the outer Cape's hydrogeologic framework, and (2) provide relatively stable, locally rough habitats within an area of seafloor dominated by mobile sand and gravelly sediment, and benefit the benthic fauna by providing shelter and a substrate amenable to burrow construction.
ArticleNew seafloor map of the Puerto Rico trench helps assess earthquake and tsunami hazards(American Geophysical Union, 2004-09-14) ten Brink, Uri S. ; Danforth, William W. ; Polloni, Christopher ; Andrews, Brian D. ; Llanes, Pilar ; Smith, Shepard ; Parker, Eugene ; Uozumi, ToshihikoThe Puerto Rico Trench, the deepest part of the Atlantic Ocean, is located where the North American (NOAM) plate is subducting under the Caribbean plate (Figure l). The trench region may pose significant seismic and tsunami hazards to Puerto Rico and the U.S.Virgin Islands, where 4 million U.S. citizens reside. Widespread damage in Puerto Rico and Hispaniola from an earthquake in 1787 was estimated to be the result of a magnitude 8 earthquake north of the islands [McCann et al., 2004]. A tsunami killed 40 people in NW Puerto Rico following a magnitude 7.3 earthquake in 1918 [Mercado and McCann, 1998]. Large landslide escarpments have been mapped on the seafloor north of Puerto Rico [Mercado et al., 2002; Schwab et al., 1991],although their ages are unknown.