In the Neotropical regions during the Quaternary period, there were periods of high annual precipitation followed by the expansion of forest formations.
Thus, during the Quaternary period, higher plateaus could have locally concentrated precipitations that preserved local wetness (Oliveira Filho and Ratter, 2000; Pennington et al., 2000) and favoured the existence of forest formations.
They create at a view of lowland neotropical vegetation alternating between closed forest and more dry open forest or savanna-like vegetation during the environmental fluctuations of the late Tertiary and Quaternary Period."
tectonic uplift or subsidence, over large regions or by more localized (orogenic) mountain building during the last 60 million years (Cenozoic era; Tertiary and Quaternary periods) and before; or these changes were caused by fluctuations of world sea-level leading to repeated flooding (and subsequent falling dry) of low lying areas in Amazonia and on the continental shelves.
Modern humans appeared near the end of the
Quaternary Period.
Five cores collected on ODP Leg 130 (in 1990) at Site 806 provide an excellent record of ice-mass fluctuations over the last two million years (the
Quaternary period).
Other researchers agree that during some times (such as the
Quaternary period starting 2 million years ago) the waxing and waning of ice sheets has triggered third-order sea level falls and rises.
Controversy over when exactly the
Quaternary Period began has raged for decades, with attempts in 1948 and 1983 to define the era.
During the past 25 years, the ocean drilling programs have recovered numerous shallow carbonate sequences, ranging in age from the late Triassic (230 million years ago) to the
Quaternary period (the last 1.6 million years), along continental passive margins and aseismic volcanic ridges in intra-oceanic basins.