The suspended matter transported by the Orinoco to the Orinoco delta originates mainly in the Colombian Andes. The four clayey minerals (kaolinite, chlorite, illite and smectite) are always present in the deltaic suspensions, the delta deposits and the gulf of Paria. Illite contents are always dominant except in those regions of the gulf of Paria situated far from the mouths of the Orinoco tributaries characterized by smectites. In the delta, illite contents which are minimal during the dry season increase noticeably during the wet season which is marked by a high Liquid and particulate matter discharge. In the delta, the clay mineralogy of the substrate is comparable to that of dry season suspensions (February), thus showing a sedimentation composed of particulate matter carried by the Orinoco and Amazon rivers. In the wet season, the high liquid and particulate discharges circulate through the delta, then enter and disperse in the Caribbean Sea and the near Atlantic. The clay mineralogy described in the gulf of Paria show that this allochthonous participation of the Amazon in the deltaic sedimentation of the Orinoco is much more pronounced there. In this region, the spatial variations in illite content show this mineral to be a good marker for circulation.