Site of Indian Shellmound
One thousand feet due west was a prehistoric mound, 400 feet long, 150 feet wide, and 14 feet high. The remains of 400 Indians with stone implements and shell ornaments were found when the mound was removed in 1908.
Erected by the Copa de Ora Chapter, D.A.R. 1914
More info:
http://bit.ly/2vfQoJN
http://ipocshellmoundwalk.homestead.com/shellmound.html
https://alamedamuseum.org/alameda-museum/collection/
http://thealamedan.org/news/alameda-history-alamedas-first-inhabitants
http://digitalassets.lib.berkeley.edu/anthpubs/ucb/text/ucp007-006-007.pdf