Problems encountered with the 14c dating of peat
Additionally, virtually all coastal-bluff exposures on Whidbey Island and on the northeastern Olympic Peninsula have been examined for this and previous investigations (Johnson and others, 1996, among others) to provide a framework for recognizing structural deformation in Quaternary strata.
Subsurface information comes from lithologic logs of water wells (figure 28; table 1).
Table 1 is a list of wells (including depth and location) used to draw stratigraphic correlation diagrams for this investigation.
The Devils Mountain fault zone is not exposed on Whidbey Island.
For this study, we used a data base, maintained by the Island County Health Department, that includes logs for more than 3,500 water wells.
8-26), aeromagnetic data (figure 3), and onshore geologic mapping in the Skagit delta (Whetten and others, 1988).
With this information, we examined exposures (figure 27) and subsurface data (figure 28, table 1) to more precisely locate faults and constrain fault histories, lengths, and slip rates.
P.), whereas an organic silty sand sample yielded a finite age of 41,380± 2,150 14C yr B. and organic material in silt yielded a finite age of 40,590 ± 530 14C yr B. These two finite ages from organic sediment are very close to the practical limit of radiocarbon dating, and they may have been contaminated by minute amounts of younger carbon.
East-west stratigraphic correlation diagrams on the north and south sides of the inferred trace of the Devils Mountain fault on northern Whidbey Island (locations, figs. The diagram north of the fault includes 19 wells within 1.4 km of the inferred fault trace and one surface outcrop (figs. Stratigraphic units inferred on the correlation diagram include pre-Whidbey Formation Pleistocene deposits, the Whidbey Formation, Possession Drift, Olympia beds, Esperance Sand Member, main body of Vashon Drift, and Everson Drift (figure 6).
The top of the interglacial Whidbey Formation is inferred to provide the most useful datum for the following reasons: 1.