Sedimentation rates in Fayetteville Green Lake, New York, U.S.A.

In Fayetteville Green Lake, past sedimentation rates can be accurately and precisely estimated by separating annual couplets or varves in dried sediment samples. Two measures were used, which serve as upper and lower limits on estimated sedimentation rate. They agree within 5 % with average annual sedimentation rate in couplets for recent years. Between 3 and 5 replicate samples are needed to reduce the half‐width of 95 % confidence intervals on individual couplet sedimentation rates to 30 g m −2 yr −1 about 5 % of average recent rates. In the late 1800s sedimentation rate averaged 392 g m −2 yr −1 and ranged between 324 and 466 g m −2 yr −1 , while in the 1970s the rate averaged 581 g m −2 yr −1 by the same measure, and ranged between 384 and 646 g m −2 yr −1 . Sedimentation rate averaged for 13 years does not vary over short distances in the profundal zone, but lateral variation in sedimentation rate can be detected for individual years over the same distance. Not all this variation was associated with the non‐uniform distribution of dark sublaminae and thin turbidites which cannot be separated from the annual layers. This indicates that although precise estimates of sedimentation rates can be made at different points in the lake, estimates will have to be made at numerous points before annual sedimentation rates for the lake as a whole can be accurately assessed.