Influence of tidal‐range change and sediment compaction on Holocene relative sea‐level change in New Jersey, USA

Abstract

We investigated the effect of tidal‐range change and sediment compaction on reconstructions of Holocene relative sea level (RSL) in New Jersey, USA. We updated a published sea‐level database to generate 50 sea‐level index points and ten limiting dates that define continuously rising RSL in New Jersey during the Holocene. There is scatter among the index points, particularly those older than 7 ka. A numerical model estimated that paleotidal range was relatively constant during the mid and late Holocene, but rapidly increased between 9 and 8 ka, leading to an underestimation of RSL by ∼0.5 m. We adjusted the sea‐level index points using the paleotidal model prior to assessing the influence of compaction on organic samples with clastic deposits above and below (an intercalated sea‐level index point). We found a significant relationship (p = 0.01) with the thickness of the overburden (r = 0.85). We altered the altitude of intercalated index points using this simple stratigraphic relationship, which reduced vertical scatter in sea‐level reconstructions. We conclude that RSL rose at an average rate of 4 mm a−1 from 10 ka to 6 ka, 2 mm a−1 from 6 ka to 2 ka, and 1.3 mm a−1 from 2 ka to AD 1900. Copyright © 2013 John Wiley & Sons, Ltd.

The contribution of glacial isostatic adjustment to projections of sea‐level change along the Atlantic and Gulf coasts of North America

“…None of the SLIPs used here were corrected for changes in the local tidal range [c.f. Horton et al, 2013]. However, we note that the majority of these SLIPs are younger than 8 ka, when estimated changes are relatively small [Hill et al, 2011].…”

Holocene Relative Sea-Level Changes from Near-, Intermediate-, and Far-Field Locations

“…We do not change the interpretation of index points from the original studies, although in one study [42] where vertical error was not specified for four index points, we assign a conservative (±1 m 2σ) error value. [46] We acknowledge that the error values of many of the index points may be underestimated, in particular because local factors that influence RSL, such as sediment compaction or tidal range change, are not considered [43]. Where necessary, we have converted radiocarbon ages into thousand calibrated years (ka) before present (BP), where the year 0 BP is conventionally taken to be 1950 CE.…”

“…This method has not been previously adopted to describe spatial variability in RSL change on a global scale and represents a [54,56], Northwest Georgia Strait, Canada [49], Southern Maine, USA [71], New Jersey, USA [43], Louisiana, USA [74], California, USA [49], St. Croix [99], Suriname and Guyana [100 ], Rio Grande do Norte State, Brazil [102], and South Shetland Islands, Antarctica [112,114]. Altitudes and interpretations of sea-level index points (including errors) have not been amended from the original publication (see section 2 for details).…”

Quantifying the Contribution of Sediment Compaction to late Holocene Salt-Marsh Sea-Level Reconstructions, North Carolina, USA

“…However, samples of salt-marsh sediment used to reconstruct sea level may have undergone post-depositional lowering (PDL) by compaction of underlying sediment (Jelgersma, 1961;Bloom, 1964;Allen, 1999Allen, , 2000van Asselen et al, 2009). PDL causes an over-estimation of the amount and rate of reconstructed sea-level rise (Horton and Shennan, 2009;Horton et al, 2013). The contribution of compaction must be quantified and removed from sea-level reconstructions to permit fair comparison among records and to ensure that the sensitivity of sea level to forcing factors is not misinterpreted or overstated.…”