Mount Diablo was a site where Bay Area native Americans worshipped for thousands of years.
The mountian was formed form tectonic movement from the Jurassic Period 190 million years ago.
The natives gave the mountian several names and the Spanish once called it “Monte Del Diablo”, which stands for “Thicket of the Devil”, after an encounter with the natives.
On August 2, 1921, Mount Diablo was designated as a California state park. That designation remains to this day.