Abstract
The rate of relative sea-level (RSL) rise at Sandy Hook, NJ (4.0 +/- 0.5 mm/yr) was higher than The Battery, NY (3.0 +/- 0.3 mm/yr) from 1900 to 2012 despite being separated by just 26 km. The difference cannot be explained by differential glacial isostatic adjustment (GIA; 1.4 +/- 0.4 and 1.3 +/- 0.4 mm/yr RSL rise, respectively) alone. We estimate the contribution of sediment compaction to subsidence at Sandy Hook using high-resolution grain size, percent organic matter, and porosity data from three upper Quaternary (<= 13,350="" cal="" yr)="" cores.="" the="" organic="" matter="" content=""><2%) is="" too="" low="" to="" contribute="" to="" local="" subsidence.="" however,="" numerical="" modeling="" of="" the="" grain="" size-depth-age-porosity="" relationship="" indicates="" that="" compaction="" of="" deglacial="" silts="" likely="" reduced="" the="" column="" thickness="" by="" 10-20%="" over="" the="" past="" 13,350="" cal="" yrs.="" while="" compaction="" rates="" were="" high="" immediately="" after="" the="" main="" silt="" deposition="" (13,350-13,150="" cal="" yrs="" bp),="" rates="" decreased="" exponentially="" after="" deposition="" to="" an="" average="" 20th="" century="" rate="" of="" 0.16="" mm/yr="" (90%="" confidence="" interval="" (c.i.),="" 0.06-032="" mm/yr).="" the="" remaining="" similar="" to="" 0.7="" mm/yr="" (90%="" c.i.="" 0.3-1.2="" mm/yr)="" difference="" in="" subsidence="" between="" sandy="" hook="" and="" the="" battery="" is="" likely="" due="" to="" anthropogenic="" groundwater="" withdrawal.="" historical="" data="" from="" fort="" hancock="" wells="" (2="" km="" to="" the="" southeast="" of="" the="" sandy="" hook="" tide="" gauge)="" and="" previous="" regional="" work="" show="" that="" local="" and="" regional="" water="" extraction="" lowered="" the="" water="" levels="" in="" the="" aquifers="" underlying="" sandy="" hook.="" we="" suggest="" that="" the="" modern="" order="" of="" contribution="" to="" subsidence="" (highest="" to="" lowest)="" appears="" to="" be="" gia,="" local/regional="" groundwater="" extraction,="" and="" compaction="" of="" thick="" quaternary="">