A number of outdoor pieces were built in this park by Heather McGill and John Roloff between 1986 and 1989, as part of the interpretive efforts for the then new nature preserve at Elkhorn Slough, near the Central California Coast. Isla de Umunnum is the name of the 5-acre island where the sculptures were made (Umunnum is Ohlone Indian for hummingbird). The most extensive piece is The Mound, made of layered shells, cut like a cross-section of a midden mound, and connected to a stagnant pool. The pieces are only partially maintained.
Isla de Umunnum