The dispersal of Amazon mud reaches from the mouth of the Amazon river to the Orinoco delta and to the eastern Caribbean, a distance of more than 1500 km. The present dispersal system has been in existence for at least 10³ years, but the deposition of mud from this system has not been constant during that period. A change from net erosion to net deposition along the Suriname coast between 1947 and 1981 was found to coincide with a shift of the trade winds from a dominantly NE to a more ENE direction from 1959 onward, accompanied by an increase in mean wind velocity. The change to net-deposition can be explained by enhanced longshore transport of suspended matter with simultaneous reduction of erosion by reduction of the onshore wave energy component. The sequence of a recent mud deposit 100-200 years old off the Amazon river mouth separated by a period of non-deposition from an older mud deposit less than 1000 years old, agrees well with indications for a wetter period in the Amazon basin and in the Colombian Andes since about 200 years BP and a wetter period between 500 and 900 y BP. This implies that during wetter periods the suspended-sediment supply from the Amazon (and the Orinoco) was (is) higher.
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