Landsat TM image showing bifurcation of the Orinoco River as it flows east from its alluvial valley out onto the delta plain.  Upstream of the delta apex, the valley is bordered by Pleistocene uplands to the north and Precambrian Guayana Shield and Pleistocene terraces to the south.  The apex of the delta plain shows a complex array of very large eastward-flowing trunk channels, large northward-flowing distributary channels, numerous flood-basin lakes, and local lateral accretion topography.  This image highlights differences in turbidity among the various channels and clearly shows the effects of the dam near the head of Caño Manamo.  Downstream (north) of the dam, waters are significantly less turbid than those present in Caño Macareo and Rio Grande.