VERA KATZ EASTBANK ESPLANADE AND GOV. TOM McCALL WATERFRONT PARK:

Alluvial Wall

According to the Portland Parks and Recreation Bureau's website, ". . . the Alluvial Wall — clinging to a concrete retaining wall — alludes to the interwoven layers of the rivers pre-industrial geology and human artifacts; an amalgam of sedimentation and erosion formed of cold-forged steel plate with bronze castings lodged between its layers."

Here are two of those castings: