Alluvial fill and terraces in ephemeral tributary.

Rio Casma, Peru, 1984.

Note high stranded pediment surface with very dark desert varnish, at the two of the slopes around this terrace are two alluvial fans, on the left the fan drains metasedimentary and volcanic bedrock and has developed a strong desert pavement and varnish. The fan on the right comes from a drainage with granitic bedrock. As the granitic rocks break down to sand size particles desert pavement and varnish do not form well on this surface.

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