Figure 3. Schematic illustration of two orders of dark and light cycles occurring in a thin section from the Cariaco series (Sample 165-1002C-3H-7, 42-45 cm). A. Varved succession. B. Grouping of varves in dark/light lower order cycles. C. Enlarged varves: (1) foraminifer shells, empty or filled with brown organic matter, (2) wispy film of organic matter in a dark layer, (3) micrite forming a light layer, and (4) clay-organic matter matrix.