Mount Diablo State Park

We had a great - but very windy - visit to Mt Diablo in late December of 2006. I made a Yahoo Trip Planner before we went, collecting information about the area. We weren’t up to braving the wind for much hiking, but we did enjoy ourselves.

At the peak, the wind and views were both breathtaking. Actually, the wind was more breathtaking, but we could still see one of the Farallons and the snow capped Sierra range. We indulged in a little geographic geekery, making note of the baseline and meridian used for surveying much of Norther California and Nevada.

From http://cdec.water.ca.gov/cgi-progs/queryFx?MTD the average wind speed when we were at the peak was 40 mph, with gusts to 59 mph.

Rock City was fascinating and beautiful—and warm and on the lee side of the wind. There is a ribbon of Eocene sandstone, the bedding layers tilted almost straight up, that wraps around the side of the mountain. The rocks are worn with odd caves and knobs, and concrete smooth surfaces (with a regrettable amount of modern petroglyphs). [There wasn’t a book for sale on the Diablo geology, but this site is great. I wish i’d seen the roadside geology guide before we went, but with the trip fresh in my mind, i have explained for me that the bright red soils i saw were “red radiolarian cherts.”]