@inbook {1463,
	title = {Oceanic dispersal and accumulation of river sediment},
	booktitle = {Continental-Margin Sedimentation: from Sediment Transport to Sequence Stratigraphy},
	volume = {IAS Special Publication},
	year = {2007},
	note = {id: 1119},
	month = {2007},
	pages = {608},
	publisher = {Blackwell Publishing Ltd.},
	organization = {Blackwell Publishing Ltd.},
	address = {Oxford},
	author = {Sommerfield, C. K. and Agston, A. S. and Mullenbach, B. L. and Drake, D. E. and Alexander, C. R. and Nittrouer, C. A. and Borgeld, J. C. and Wheatcroft, R. A. and Leithold, E. L.},
	editor = {Nittrouer, C. A.}
}
@article {601,
	title = {On sediment accumulation rates and stratigraphic completeness: Lessons from Holocene ocean margins},
	journal = {Continental Shelf Research},
	volume = {26},
	year = {2006},
	note = {109ueTimes Cited:24Cited References Count:61},
	month = {Nov},
	pages = {2225-2240},
	abstract = {Stratigraphic completeness is a fundamental consideration when deciphering the mass accumulation history of sediments and the geologic record of earth and ocean processes. In this study, stratigraphic completeness was examined in the context of late Holocene sedimentary successions using published sediment accumulation rates for five ocean margin systems (Amazon shelf, Hudson estuary, northern California shelf, Mid-Atlantic slope, Santa Monica Bay). Plots of mass accumulation rate versus time span of averaging were used to determine how rates scale with measurement period, and to estimate levels of stratigraphic completeness for comparison within and among margin systems. Statistically significant inverse correlations between accumulation rate and time span of averaging are indicated for all but one of these systems-most of the sedimentary records examined are stratigraphically incomplete. At the 10(3)-yr level of resolution, completeness is 20-48\% for strongly tidal estuarine (Hudson estuary) and deltaic shelf (Amazon shelf) sites, 51-91\% for accretionary shelves (northern California shelf) and slopes (Mid-Atlantic slope), and 85-100\% for a sediment-starved slope (Santa Monica bay). Mass accumulation rates converge to a relatively narrow range (0.01-0.1 g cm(-2) yr(-1)) at the 10(4)-yr level of resolution, consistent with the notion that there are universal controls on sediment accumulation rate, i.e., rate of sea-level rise and sediment supply. Among sites on the Amazon and northern California shelves, within-system completeness varies by similar to 10-20\% on account of site-specific sedimentary processes that preferentially trap or disperse suspended sediment. Overall, stratigraphic completeness increases with water depth shelf-to-slope, yet depth is not a robust predictor of completeness in general owing to differences in strata-forming processes among shallow-marine environments. Significantly, completeness varies inversely with instantaneous deposition rate as the most sediment-rich systems tend to exhibit the most incomplete sedimentary records. The findings of this study emphasize the importance of considering time span and fidelity when interpreting the accumulation history of modern and Holocene sedimentary strata. (c) 2006 Elsevier Ltd. All rights reserved.},
	issn = {0278-4343},
	doi = {10.1016/j.csr.2006.07.015},
	author = {Sommerfield, C. K.}
}
@article {572,
	title = {Latest Holocene evolution and human disturbance of a channel segment in the Hudson River Estuary},
	journal = {Marine Geology},
	volume = {218},
	year = {2005},
	note = {942iaTimes Cited:11Cited References Count:49},
	month = {Jun 30},
	pages = {135-153},
	abstract = {The latest Holocene sedimentary record of a cohesive channel and subtidal shoal in the lower Hudson River Estuary was examined to elucidate natural (sea-level rise, sediment transport) and anthropogenic (bulkheading, dredging) influences oil the recent morphodynamic evolution of the system. To characterize the seafloor and shallow subbottom, similar to 100 km of high-resolution seismic reflection profiles (chirp) were collected within a 20-km reach of the estuary and correlated with sediment lithologies provided by eight vibracores recovered along seismic lines. Sediment geochronology with Cs-137 and C-14 was used to estimate intermediate and long-term sedimentation rates, respectively, and historical bathyrnetric data were analyzed to identify regional patterns of accretion and erosion, and to quantify changes in channel geometry and sediment volume.The shoal lithosome originated around 4 ka presumably with decelerating eustatic sea level rise during the latest Holocene. Long-term sedimentation rates on the shoal (2.3-2.6 mm/yr) are higher than in the channel (2 mm/yr) owing to hydrodynamic conditions that preferentially sequester suspended sediment on the western side of the estuary. As a result, the shoal accretes oblique to the principal axis of tidal transport, and more rapidly than the channel to produce an asymmetric cross-section. Shoal deposits consist of tidally bedded muds and are stratified by minor erosion surfaces that seismic profiles reveal to extend for I Os of meters to kilometers. The frequency and continuity of these Surfaces suggest that the surficial shoal is catastrophically stripped on decadal-centennial time scales by elevated tidal flows. tidal erosion maintains the shoal at a uniform depth below sea level and prevents it from transitioning to an intertidal environment. Consequently, the long-term sedimentation rate approximates the rate of sea-level rise in the lower estuary (1-3 mm/yr).},
	issn = {0025-3227},
	doi = {10.1016/j.margeo.2005.02.026},
	author = {Klingbeil, A. D. and Sommerfield, C. K.}
}
@article {685,
	title = {Across-shelf sediment transport since the Last Glacial Maximum, southern California margin},
	journal = {Geology},
	volume = {32},
	year = {2004},
	note = {808fbTimes Cited:19Cited References Count:36},
	month = {Apr},
	pages = {345-348},
	abstract = {Correlation of continental shelf-slope stratigraphy in Santa Monica Bay (southern California) with Ocean Drilling Program records for nearby slope-basin sites has illuminated the timing and scale of terrigenous sediment dispersal on margin since the Last Glacial Maximum (LGM). Marine flooding surfaces preserved in a transgressive sequence on the Santa Monica Shelf provide a key link between base-level elevation and sediment transport across shelf. Sediment-accumulation rates at slope-basin sites were maximal ca. 15-10 ka, well after the LGM, decreased during the 12-9 ka transition from fluvial-estuarine to fully marine conditions on the shelf, and decelerated throughout the Holocene to 30\%-75\% of their values at the LGM. The deceleration is interpreted to manifest a landward shift in the margin depocenter with the onset of transgressive sedimentation beginning when sea level surmounted the shelf edge ca. 13 ka, as predicted by sequence-stratigraphic models. However, the records make clear that factors other than base level modulated slope-basin accumulation rates during the deglaciation.},
	issn = {0091-7613},
	doi = {10.1130/G20182.1},
	author = {Sommerfield, C. K. and Lee, H. J.}
}
@article {642,
	title = {Magnitude and variability of Holocene sediment accumulation in Santa Monica Bay, California},
	journal = {Mar Environ Res},
	volume = {56},
	year = {2003},
	note = {Sommerfield, Christopher KLee, Homa JengResearch Support, U.S. Gov{\textquoteright}t, Non-P.H.S.England2003/03/22 04:00Mar Environ Res. 2003 Jul-Aug;56(1-2):151-76.},
	month = {Jul-Aug},
	pages = {151-76},
	abstract = {The spatial variability of Holocene (past 10,000 years) sediment accumulation in Santa Monica Bay (California) was examined to identify controls sediment trapping in a bathymetrically complex coastal embayment and to provide geologic context for the post-industrial sedimentary record and associated pollution gradients. Sediment chronologies based on downcore AMS 14C dates were used to quantify long-term (millennia) accumulation rates in an effort to elucidate particle-transport pathways and sinks. Sediment accumulation rates for the full range of bayfloor environments (50-630 m water depths) range from 22 to 102 mg/cm(2)/year (15-88 mm/100 year), have an overall mean of 51+/-21 mg/cm(2)/year (1 sigma, n=11), and are comparable to rates reported for adjacent borderland basins. Maximal accumulation rates on the Malibu shelf and within a reentrant to Redondo canyon are interpreted to reflect (1) proximity to sediment sources and (2) localized oceanographic and topographic conditions conducive to sediment trapping and deposition. The 14C-derived accumulation rates are 2-10 times lower than rates determined through (210)Pb geochronology for the same sites in a related study, revealing that Holocene sediment accumulation has been non-steady-state. Santa Monica Bay is an important sink for suspended matter; averaged over the past several millennia a mass of sediment equivalent to 10-80\% of the modern annual river supply is sequestered yearly. Net influx of suspended matter derived from the adjacent Palos Verdes shelf is evinced by a concentration gradient of p,p{\textquoteright}-DDE in bayfloor sediments, whereas the distribution of anthropogenic silver suggests transport from Santa Monica shelf to the southeastern boundary of the bay. The results of this study provide new insight to the long-term fates of particulate matter in Los Angeles coastal waters.},
	issn = {0141-1136 (Linking)},
	doi = {10.1016/S0141-1136(02)00329-X},
	author = {Sommerfield, C. K. and Lee, H. J.}
}
@article {735,
	title = {Shelf record of climatic changes in flood magnitude and frequency, north-coastal California},
	journal = {Geology},
	volume = {30},
	year = {2002},
	note = {551ucTimes Cited:46Cited References Count:34},
	month = {May},
	pages = {395-398},
	abstract = {Continental-shelf deposits off the Eel River, north-coastal California, document a recent increase in the magnitude and frequency of major hydrologic floods (greater than or equal to10 yr recurrence interval). The shelf record reveals a sudden, three-fold increase in sedimentation rate ca. 1954 and a concomitant increase in the frequency of preserved flood beds. Comparison of sedimentary and river-discharge records reveals that major floods after ca. 1950 had a more pronounced effect on coastal sediment delivery and accumulation offshore than previous recorded events of similar magnitude, and that stratigraphic preservation of flood events is highly dependent on flood frequency and net sedimentation rate. We contend that this change in marine sedimentation is a response to documented climatic phenomena that have increased the frequency of major floods throughout the western United States during the past half century, together with intrabasinal impacts of extreme floods in 1955 and 1964. Anthropogenic increase in watershed-sediment production is a probable secondary factor.},
	issn = {0091-7613},
	doi = {10.1130/0091-7613(2002)030<0395:Srocci>2.0.Co;2},
	author = {Sommerfield, C. K. and Drake, D. E. and Wheatcroft, R. A.}
}
@article {2169,
	title = {Processes and rates of Holocene sedimentation in Santa Monica Bay, CA},
	journal = {EOS},
	volume = {Transactions of the American Geophysical Union},
	year = {2000},
	note = {id: 139},
	month = {2000},
	pages = {OS251},
	author = {Sommerfield, C. K. and Lee, H. J.}
}
@article {2255,
	title = {Decadal to millennial variability of fluviomarine sedimentation on the northern California continental shelf},
	journal = {EOS},
	volume = {Transactions of the American Geophysical Union},
	year = {1998},
	note = {id: 1328},
	month = {1998},
	pages = {F457},
	author = {Sommerfield, C. K.}
}
@article {866,
	title = {Sedimentary carbon-isotope systematics on the Amazon shelf},
	journal = {Geo-Marine Letters},
	volume = {16},
	year = {1996},
	note = {Ty588Times Cited:12Cited References Count:33},
	month = {Feb},
	pages = {17-23},
	abstract = {Sedimentary carbon systematics on the Amazon continental shelf were investigated using C-14 and delta(13)C measurements of sedimentary organic materials. Mass balance calculations indicate that the C-14 content of modern shelf muds results from burial of old (similar to 5000 yr BP) terrestrial soil carbon and bomb-C-14-enriched marine carbon, implying that most of the bomb-labeled riverine particulate carbon is not buried on the shelf. The C-14 signature of Amazon shelf deposits records the effects of both biogeochemical and sedimentary processes active in this dynamic environment.},
	issn = {0276-0460},
	doi = {10.1007/Bf01218832},
	author = {Sommerfield, C. K. and Nittrouer, C. A. and DeMaster, D. J.}
}
@article {856,
	title = {Stratigraphic Evidence of Changes in Amazon Shelf Sedimentation during the Late Holocene},
	journal = {Marine Geology},
	volume = {125},
	year = {1995},
	note = {Rt489Times Cited:33Cited References Count:65},
	month = {Jul},
	pages = {351-371},
	abstract = {Late Holocene sedimentation on the Amazon shelf was investigated using a combination of seismic, sedimentological, and geochronological methods. Piston cores collected in the subaqueous delta region during A Multidisciplinary Amazon Shelf Sediment Study (AmasSeds) penetrated a regionally traceable (1.25 x 10(4) km(2)) seismic discontinuity, which corresponds to a dense relict-mud reflector overlain by acoustically transparent sediment. Distinct offsets in profiles of wet-bulk density, P-wave velocity, and Pb-210 activity are noted in cores at the reflector horizon (unconformity), signifying a past change in sedimentation conditions on the shelf. Bulk-sediment C-14 dating indicates net depositional conditions for the subaqueous delta from >1800 yr B.P. to 700 yr B.P. and a net erosional phase from about 700 yr B.P. to 100 yr ago. Sedimentological evidence of the erosional phase includes lag deposits and burrows present at the unconformity surface in piston cores. The deposits above and below the unconformity are similar with respect to grain-size parameters and sedimentary structures, suggesting that environmental conditions during the two depositional periods were similar. According to C-14 dates of coastal deposits, the shoreline of Amapa State, Brazil served as a major depocenter of Amazon mud during the erosional phase on the shelf. Pb-210 geochronology indicates that the most recent phase of sediment accumulation in the study area commenced about 100 yr ago, resulting in rapid progradation of topset deposits and burial of relict strata. In the present environment, oceanographic and meteorologic processes cause along-shelf variations in sediment dispersal and depositional patterns, and about 1400 km(2) of the erosional relict deposits are still exposed at the seabed. The short time scales over which Amazon shelf strata respond to changes in the physical environment preclude the influence of relative sea-level cyclicity on recent sedimentation patterns. During the late Holocene, sedimentation and strata formation on the Amazon shelf are linked to fluvial, oceanographic and meteorologic processes that affect sediment supply, deposition and erosion.},
	issn = {0025-3227},
	doi = {10.1016/0025-3227(95)00019-U},
	author = {Sommerfield, C. K. and Nittrouer, C. A. and Figueiredo, A. G.}
}
