Inner Coast Range

Flag Hill at Sunol Wilderness is a slab of ancient sea floor which, in response to pressure from below, was tilted up more on one side than the other, revealing a cross-section of its sedimentary layers.

The hill shows a vegetation pattern typical of the inner coast ranges. During summer, the hot sun dries the south-facing slope. Only grassland and soft chaparral can survive under these conditions. On the north-facing slope where moisture lasts longer, trees thrive.

Sunol is one of the most beautiful parks in the Bay Area.