sentences:  An abandoned rock quarry is situated about 0.3 miles (500 m) north of State Route 12 on the west bank.Where Nunns Canyon Road terminates, Calabazas Creek enters into a 1,290 acre (5.2 km²) open space nature preserve owned and managed by the Sonoma County Open Space District; as of 2007, there is no public access to this prior holding of the Beltane Ranch, which has been named the Calabazas Creek Open Space Preserve.In addition to a relatively pristine riparian zone, the upper Calabazas Creek has a high quality California oak woodland, much of which is an undisturbed ecosystem with considerable biodiversity, particularly in the upper 1.7 miles (2.5 km) of the headwaters.