Salt pools (shallow, water-filled depressions) are common landforms in north-temperate salt marshes. Despite their widespread distribution, the origin of pools as primary or secondary features of salt marshes remains uncertain and their description in the geologic record unclear. This study combines analyses of modern sediments and cores to determine pool origin and describe pool deposits. We collected samples from tidal-flat, tidal-creek, salt-pool, low-marsh, and high-marsh environments and 23 Dutch cores through extant and paleopools from salt marshes in Ogunquit, Wells, Brunswick, Gouldsboro, Addison, and Lubec, Maine. Salt-pool sediment is a dark gray, high-water-content mud with intermediate total organic carbon values (2.21–9.08) and typically lower carbon-to-nitrogen ratios than low- and high-marsh sediments. Pool sediment contains a suite of biological macrofossils; most common are drupes of the submerged aquatic plant Ruppia maritima and the gastropod Hydrobia totteni. Microfossil analyses reveal no unique foraminiferal assemblages associated with pools, though mites (subclass Acarina) were commonly found within pool sediment. Cores reveal that most studied pools are of secondary, not primary, origin and that many are dynamic features of these salt marshes, some rapidly in-filling with sediment when drained. Our results suggest that local pool dynamics (that may or may not be linked to larger regional signals, like sea-level change) dominate the geologic records in many of these marshes. Correct interpretations of core records hinge on the correct identification of the cores' subunits; with the salt-pool unit now identified and defined, re-examinations and potential reinterpretations of salt-marsh stratigraphic records are warranted.