Figure 9: SILURIAN OCEANIC REDOX PROFILE. Calculated after Wilde (1987) using a mean Silurian atmospheric oxygen content of 50% PAL [Present Atmospheric Level] (Budyko, Ronov and Yanshin, 1987, p. 101) for tropical [Surface Water Temperature = 25°C] and non-glacial [Surface Mixed Layer: 0 to 100 meters; Main Pycoocline: 100 to 3000 meters; and Deep Layer > 3000 meters (Wilde and Berry, 1982)] conditions.