In 1930, the west end of Silva Island was dynamited away to accommodate the north end of the Richardson Bay Bridge. Preliminary archeological work done in 1907 identified the northeast side of Silva Island as a prehistoric site. It was named “Marin 17”. In 1980 a San Francisco State professor and his students began three years of painstaking excavation in three shafts. They unearthed remarkable evidence that Marin history went back to about 3,530 BC. Artifacts lifted to the surface from as deep as 22 ft. were tested using carbon-14 and obsidian hydration dating techniques. In 1984, the professor was unable to secure a permit to continue digging. Neighbors feared that children would fall into the shafts. Without informing the professor, the landowner filled the three shafts. In 2002, a residential development including recreational facilities was constructed on Silva Island. The 32 condos in 8 buildings were offered at $1.2 to $2.0 million. The development has the Spanish name “De Silva Island” although the Portuguese “Da Silva Island” may be more appropriate. Up to date maps continue to designate the island as “Silva Island” although not even the oldest maps indicate that it is completely surrounded by water.