Figure 3. Summary of some of the marine and terrestrial observations that indicate an intensification of the monsoon in the late Miocene (10-8 Ma) and a model simulation of a possible evolution of monsoon runoff. A. Abundance of planktonic foraminifer Globigerina bulloides and radialarian Actinoma spp. that indicate active upwelling induced by southwest monsoonal winds (from ODP Site 722, Arabian Sea). B. Oxygen and carbon isotopes measured in pedogenic carbonates from Pakistan indicating more seasonal climates and a decrease in atmospheric CO₂ possibly due to monsoon related weathering (data from Quade et al., 1989). C. Normalized, mean terrigenous sediment flux to the northern Indian Ocean that indicates active uplift and fluvial deposition in the late Miocene (from Rea, 1992). D. A model simulation of monsoon runoff using the Molnar model for uplift history (11-8 Ma) and the coupled effects of elevation change and orbitally-induced solar radiation changes (from Prell and Kutzbach, 1997).

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