Quaternary geology of the Rhode Island inner shelf

Needell, Sally W.; O'Hara, Charles J.; Knebel, Harley J.

doi:10.1016/0025-3227(83)90033-6

Cited by 8 publications

(4 citation statements)

References 25 publications

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“…Overlying the metamorphic bedrock are late Cretaceous-Tertiary coastal plain sediments in the southern part of the sound, and Pleistocene glacial deposits and Holocene fluvial, estuarine, and transitional sediments throughout the sound ( Fig. 2; McMaster et al 1968;O'Hara and Oldale 1980;Needell et al 1983). The coastal plain sediments, which contain deeply eroded channels, form a cuesta across the southern RIS (McMaster et al 1968).…”

Section: Physical Settingmentioning

confidence: 99%

“…2; O'Hara and Oldale 1980). During glacial recession, Glacial Lake Rhode Island formed behind the end moraines, and outwash sediments, deposited in the lake, added to the total thickness of glacial deposits that in places now exceeds 40 m (O'Hara and Oldale 1980; Needell et al 1983;Oakley and Boothroyd 2013). During and after lake drainage, while sea level was near lowstand, rivers cut drainage channels into the glacial deposits, often at the locations of previously eroded valleys (Needell et al 1983).…”

Section: Physical Settingmentioning

confidence: 99%

“…During glacial recession, Glacial Lake Rhode Island formed behind the end moraines, and outwash sediments, deposited in the lake, added to the total thickness of glacial deposits that in places now exceeds 40 m (O'Hara and Oldale 1980; Needell et al 1983;Oakley and Boothroyd 2013). During and after lake drainage, while sea level was near lowstand, rivers cut drainage channels into the glacial deposits, often at the locations of previously eroded valleys (Needell et al 1983). As sea level rose, estuarine and transitional sediments were deposited, infilling many of the depressions left by the late Pleistocene fluvial erosion; as the transgression migrated across the shelf, the unconformity that now separates the Holocene marine sediments from the underlying older deposits was created ( Fig.…”

Section: Physical Settingmentioning

confidence: 99%

“…As sea level rose, estuarine and transitional sediments were deposited, infilling many of the depressions left by the late Pleistocene fluvial erosion; as the transgression migrated across the shelf, the unconformity that now separates the Holocene marine sediments from the underlying older deposits was created ( Fig. 2; O'Hara and Oldale 1980; Needell et al 1983).…”

Section: Physical Settingmentioning

confidence: 99%

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Character, distribution, and ecological significance of storm wave-induced scour in Rhode Island Sound, USA

2014

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Multibeam bathymetry, collected during NOAA hydrographic surveys in 2008 and 2009, is coupled with USGS data from sampling and photographic stations to map the seabed morphology and composition of Rhode Island Sound along the US Atlantic coast, and to provide information on sediment transport and benthic habitats. Patchworks of scour depressions cover large areas on seaward-facing slopes and bathymetric highs in the sound. These depressions average 0.5-0.8 m deep and occur in water depths reaching as much as 42 m. They have relatively steep well-defined sides and coarser-grained floors, and vary strongly in shape, size, and configuration. Some individual scour depressions have apparently expanded to combine with adjacent depressions, forming larger eroded areas that commonly contain outliers of the original seafloor sediments. Where cobbles and scattered boulders are present on the depression floors, the muddy Holocene sands have been completely removed and the winnowed relict Pleistocene deposits exposed. Low tidalcurrent velocities and the lack of obstacle marks suggest that bidirectional tidal currents alone are not capable of forming these features. These depressions are formed and maintained under high-energy shelf conditions owing to repetitive cyclic loading imposed by high-amplitude, long-period, stormdriven waves that reduce the effective shear strength of the sediment, cause resuspension, and expose the suspended sediments to erosion by wind-driven and tidal currents. Because epifauna dominate on gravel floors of the depressions and infauna are prevalent in the finer-grained Holocene deposits, it is concluded that the resultant close juxtaposition of silty sand-, sand-, and gravel-dependent communities promotes regional faunal complexity. These findings expand on earlier interpretations, documenting how storm wave-induced scour produces sorted bedforms that control much of the benthic geologic and biologic diversity in Rhode Island Sound.

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Section: Physical Settingmentioning

confidence: 99%