ABSTRACT
Clearly many data are needed before reliable climatic histories of the Amazon Basin can be constructed. The principal watersheds drain the different climatic regions bordering on the Amazon Basin. But the hypothesis of equatorial aridty rests also on observations for aridity in glacial times elsewhere in the tropics, and on landform data suggesting local aridity within parts of the Amazon Basin at unknown times in the past. Were it not for the attraction of the refugial hypothesis put forward by Haffer, these circumstantial data could scarcely have led to the aridity hypothesis. For Quaternary scientists the refugial hypothesis will have widespread interest only to the extent that it can be tested with independently dated evidence for past climates. At least one of the climatic systems impinging on the Amazon Basin, therefore, has been shown to be capable of wide fluctuation within the Holocene.
