Figure 3. Downcore variations in abundance and fragmentation of planktonic foraminifers, dissolution susceptible species, and occurrences of other microfossils and pyrite tubes. On the right is a summary of lithostratigraphy, biostratigraphy, and magnetostratigraphy. For fragmentation in planktonic foraminifers, the following scale is used: B = barren (0 on tray), F = few (0-10 tests), C = common (10-20), and A = abundant (more than 20). For estimates of pyrite tube abundance, the following scale is used: B = barren (0 on tray), F = few (1-3 specimens), C = common (3-5), and A = abundant (more than 5).