Our local volcano is now dressed in its finest greenery, so this is an ideal time to stroll around Sibley Volcanic Preserve (map).  Typically the scenery is wonderful before things dry up and brown out – just look at the panorama snapped this week.

Volcanic Time Capsule

Besides soaking in the views, it’s also worth contemplating the 10-million-year time capsule underneath your feet.  Sibley is one of four volcanoes that originally erupted near San Jose, and slowly traveled northwards.  Presumably it will pass us by, in another 10 million years or so.

Interestingly, the Sibley volcano tipped sideways and and was pretty much hidden from view.  When gravel rock mining took place years ago, volcanic features became more evident.  A few Berkeley geologists discovered this wonder and have studied the rocks and formations in detail.

One of these Berkeley geologists, Steve Edwards, first mapped the area in the 1970s and later joined the East Bay Regional Park District.  He shared the geological underpinnings in KQED’s Quest program last July.

Touring The Volcano

Just like all the earthquakes around here, the volcanic activities were triggered by plate tectonics.  You can walk up to Round Top (1,763 ft), the highest point in the park, where Pacific and North American plates crashed together and molten basalt lava flowed.

Then walk a quarter mile northeast, and arrive at the volcano top near the gravel rock quarry’s edge.  It turns out there are all kinds of lava flows, bake zones and lava holes scattered throughout Sibley as well.

Stop and stare at the basalt rock, and all their unusual shapes.  Geologist Andrew Alden recently pointed out spheroidal weathering.  “To paraphrase an old Grateful Deadhead saying,” said Alden, “the smaller they grow, the rounder they get.”

So head up to Sibley Preserve, for another perspective about your local volcano – those rocks actually tell quite a story.

More info:   Sibley Volcano Regional Preserve Exploration – Voice of the Volcano – Basalt of Sibley Volcano – Sibley Volcanic Preserve – Sibley Trail Map

Because Sibley Volcanic Preserve is just up the road, it’s easy to take human visitors to see the unusual volcanic remains and stellar natural views.

What about celebrating its bovine visitors?  While Bessie and her cousins are grazing there, they make a walk more special any day.

Let’s see how the cows appear as you head up the hills.  Depending on your hiking approach, you may first see the fencing which alerts to the fact that cattle are nearby… but where?

After reading the warning, you enter and close the gate carefully behind you.  There’s no sign of the beasts yet, but you may be lucky enough to run into our iconic California poppies.

Without much fanfare, a single cow or two will finally emerge.  Here’s a snapshot of Bessie, who’s clearly “on watch” and surveying walkers coming up the trail.  Other cows are quietly grazing after you crest the hill.

So while we typically appreciate Sibley’s great natural and Bay Area vistas, we should celebrate the local cows too.  The last time I took a walk, the bovines didn’t greet me – but I expect them to return soon.

Today, I decided to display some Sibley Volcanic Preserve imagery.  Sibley is sui generis in the East Bay Parks – and a convenient volcano right in our neighborhood.

Normally I think of Sibley basking in its East Bay glory.  I expect to see amber waves of grain, the volcano and its cool labyrinth, or else the typical views to San Francisco.  We always take visitors to Sibley and hear the oohs and aahs about how lucky we are to live here.

Sibley also inspires photographers to create art.  These images are taken at special moments, such as the spring when the grass is green or on days with amazing sunrises.  Have you ever seen Sibley looking so lovely?