Checking Out Mount Diablo's Biologic Overburden

Mt. Diablo is one of California's most spectacular state parks. Rising 3,847 feet above the Bay Area, the mountain is one of the most prominent in the state. It served as the starting point for surveying property line across Central California and Nevada. And it has marvelous geology: thrust faults, ocean crust, Franciscan chert, thick sequences of sandstone and coal, and a rich paleontological record. It also has some living overburden as well.

"Overburden" is a term used for the dirt and rock that overlies some valuable mineral or ore, like coal. Such rock (and all the living stuff on it) is quarried away and discarded. We geologists (and me especially) can sometimes miss the stuff that gets between us and our rocks. On field trips sometimes, I chafe a little when the attention of my students is drawn towards a squirrel or a deer instead of the incredibly important rock exposure that I'm talking about. But sometimes I get distracted too.

I see raccoons fairly often as I drive home across the creek that runs north of my town, but usually at night. Before today I had only one decent photograph of one, but as we got out to explore the Rock City at Mount Diablo, some of our students spied one. He was clearly a camp raccoon, as he didn't seem to bothered by all the cameras that were snapping.

The semester is over at my college, but the Geology Club never managed to schedule a field trip during the semester as is our tradition. Now that finals are over, the stress levels dropped, and our geology students were ready to hit the road and have a bit of fun. We headed west into the Coast Ranges for a tour of California's largest coal mine (and think about that for a moment; did you know that California once had coal mines?). It's called the Black Diamond Mine, and is part of a regional park above the town of Antioch in the Sacramento Delta. That tour was spectacular, and will also be part of a future blog post.

We had time after the tour, so we headed up nearby Mount Diablo. Despite the incredibly dry conditions this year (the state is still suffering an exceptional and unprecedented drought), there were some gorgeous wildflowers around the summit trail.

I don't know wildflowers anything like I know minerals, but I can buy books in the park visitor center! The yellow flower above is endemic to Mt. Diablo, and not too surprisingly is called the the Mt. Diablo Globe Lily ( Calochortus pulchellus).

 The orange flower above is the Wind Poppy (Papaver heterophylla). Below is a Red Larkspur (Delphinium species).

The flower below really caught my eye. It's a Butterfly Tulip (Calochortus venustus). I realized today that I have been visiting Mount Diablo in the summer or fall, and I've been missing some real flower shows of species I've never seen before, including a number of those in the post

I think the one below is a Western Wallflower (Erysimum capitatum), but I accept corrections.

It was a beautiful day in the Coast Ranges!

The Other California: The Thicket of the Devil (Saturday's Mystery Photo Revealed)

Saturday's mystery photo was quickly identified by several readers, which didn't surprise me, given the uniqueness of the Transamerica Building of San Francisco. If I had put my other picture up instead, even more people would have identified the city in a split second:

You may have to click on the photo above to see it, but that's the Golden Gate Bridge and Marin Headlands in the far distance. Most of those who guessed where I was considered the hills above Oakland, which certainly makes sense, but JRepka came closest when he speculated that I might have been using a zoom lens while standing on Mount Diablo. That's exactly what I was doing.

Mt. Diablo holds a special place in California history. Anyone who owns property in the central part of the state quite likely owes the accurate locations of their land to the presence of the peak at a sort of structural nexus over the Sacramento Delta. The peak is relatively short, not even quite 4,000 feet, but its position allows one to see an incredible swath of real estate, from Lassen Peak to the north, to the vicinity of Sequoia National Park to the south, much of the Central Valley, and the Bay area from Loma Prieta Peak to St. Helena Peak. Soon after California became a state, Diablo was selected as the initial survey point for the grid pattern that established property lines in the state: the Township and Range System.

Without going into gory detail (that privilege belongs to the unfortunate students in my lab this week), the Township and Range system established consistent survey boundaries at a time when the federal government was using the prospect of free land to aid in the "settlement" of the western United States in the late 1800's and early 1900's (we shall disregard for the moment the fact that numerous Native Americans had lived on that land for centuries, and had to be "cleared" off of it to make room for "settlers"). By occupying and farming the land for five years, practically anyone could own their own piece of land.

The spectacular view from the summit led early on to claims that Mt. Diablo had the greatest "viewshed" in the world (viewshed: the total amount of land visible from the summit). This claim has been debunked, but the misconception persists. The fact doesn't detract from the stunning vista from the summit observation deck.

The name of the peak relates to a story from the early 1800's when some Native Americans (Chupcans) escaped Spanish control and hid in a willow thicket. The Spanish soldiers called the place the "Thicket of the Devil" (Monte del Diablo), but the name was later misinterpreted as Mount Diablo.

The peak and surrounding landscape is protected today as Mt. Diablo State Park, which encompasses some 20,000 acres (park brochure here). The park is nicely developed with picnic areas, group and individual campsites, and an extensive system of hiking trails. The park is very popular with Bay Area folks, but I suspect the mountain is little known outside of California. It is well worth a visit when you are in the region.

Lessee, the park's name, the survey stuff, the park facilities, the view, what am I forgetting? Oh, there's no description of the geology of the park. It's fascinating, but too extensive to cover tonight. Look for it in a coming post!

The Other California is my series on the lesser-known but geologically interesting corners of my beautiful state.