PREPARATION TECHNIQUES

Materials used in the biostratigraphic analyses were taken from core catchers and within the split cores (usually one sample per section). Smear slides from these samples were examined for stratigraphically significant and other diatom species. Samples with a low overall abundance of diatoms were processed with hydrogen peroxide and 10% hydrochloric acid. Strewn slides were prepared from the acid-cleaned samples, and when necessary, the cleaned material was also sieved at >20 µm to remove excess clay material. Slides were routinely examined on a Zeiss compound microscope at 630x and 1000x, the higher power being reserved mainly for taxonomic identification. Slides examined from Site 1095 were generated using a quantitative pipetting technique.

Abundance of diatoms were based on the number of specimens observed per field of view at 630x. These abundance estimates were recorded as follows:

A = abundant (>10 valves per field of view).

C = common (>1 valve per field of view).

F = few (>1 valve per 10 fields of view and <1 valve per field of view).

R = rare (>3 valves per traverse of coverslip and <1 valve per 10 fields of view).

X = present (<3 valves per traverse of coverslip, including fragments).

B = barren (no valves observed in slide).

Preservation of diatoms were determined qualitatively and recorded as follows:

G = good (slight to no fragmentation and dissolution).

M = moderate (moderate fragmentation and dissolution).

P = poor (severe effects of fragmentation and dissolution).