Amazon: a river coming together
Andean uplift, erosion, sedimentation and changing lowlands together reshaped Amazon drainage. This was not one giant river suddenly reversing. The diagram explains connectivity, not exact ancient channels or scale.
Andean uplift, erosion, sedimentation and changing lowlands together reshaped Amazon drainage. This was not one giant river suddenly reversing. The diagram explains connectivity, not exact ancient channels or scale.

Annual surface temperature from CESM (T): a model estimate, not a direct observation of the past.
0 Ma: pre-industrial climate/CO₂; modern sea-level and O₂ references.
Glacial-interglacial cycles with 120m+ sea level swings. Homo sapiens spread from Africa across the globe, and most megafauna went extinct.
Annual model means · 0 Ma: pre-industrial
Present