USGS Map of Ventura County, 1930 - $500

Very large geologic map and cross sections of Ventura County (and western Los Angeles County) dating from the 1930s.
From USGS Bulletin 753.
38 by 56 inches under plexiglass.
I have had this some 50 years having found it in a cardboard tube in an abandoned water well shed in Simi Valley in the early 1970s.
Comparable to the USGS Hoots map of Los Angeles County published in the same time frame.
Rare as such.