Results from modern and ancient sediments suggest that a boron-illite equilibrium, reflecting salinity, is established at the time of deposition. This condition is not appreciably changed by subsequent processes of diagenesis and lithification. Equivalent boron in thirteen samples, from two augerholes through Dovey Estuary sediments, ranges between 260 p.p.m. and 370 p.p.m. and averages 336 ± 29 p.p.m. (95% confidence limits).
Salinity conditions in the present estuary vary greatly. A very significant direct correlation exists between equivalent boron and inferred depositional salinity of Dovey Estuary sediments.