Eagle Rock is 2488 feet above sea level and is on Empire Grade (just past Jamison Creek Road) above Boulder Creek, CA 95006.
The Topo map shows a lookout tower at Eagle Rock.
That lookout tower is within Big Basin Redwoods State Park.

For more information and the rules for Field Day, check out the ARRL Field Day page.

Below are a few maps collected, from various places, to help find Eagle Rock. Click on the appropriate one to go to the original source.

73's -- Martin W6LHI (was KG6QPB)