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Over the last couple years, I've been more and more tempted by Mulholland Hill, the ridge shared by Moraga and Orinda that dominates its area and shelters the former village of Rheem. Tempted because I crave summits, but also tempted because its rocks, named the Mulholland Formation, are interpreted as the youngest in the region. The Mulholland Formation is mapped in two shades of light tan on the geologic map, due east of Oakland. [ 553 more words ]
https://oaklandgeology.wordpress.com/…/the-rocks-of-mulhol…/
About Geology shared Zion National Park's post.
I loathe these things. Please don't make them.
A curious but destructive practice among some park visitors is the building of little towers made of stones. These piles of rocks are called “cairns.” They may ...in some cases have a useful purpose such as defining a critical route over hard ground where there is no visible path or perhaps marking an otherwise obscure trail junction. In Zion National Park trails are well used and the route is almost always obvious. Trail intersections are signed with directional arrows and mileage so cairns are not needed. Most often, visitor-built cairns appear with no intent to direct hikers, but seemingly erected as a personal mark left behind, perhaps just as a way to say “I was here.”
Leaving your mark, whether carving your initials in a tree trunk, scratching a name on a rock, or stacking up stones is simply vandalism. Visitors who build cairns probably don’t look at building cairns as vandalism since rocks can be unstacked easily, but moving rocks around still can lead to resource damage by exposing soil to wind and water erosion. Moving rocks also disturbs the many critters that make their home in the protected underside of a rock. Leaving behind stacks of rocks also can lead hikers astray, possibly into dangerous terrain. Most importantly, most visitors enter the back country to get away from signs of civilization and do not want to see mementos left by others, whether stacked rocks, trash, or graffiti. So please, enjoy the park but leave rocks and all natural objects in place.
Pictured below are cairns that had been erected on the Angels Landing summit plateau along with a photo of the site after restoration by park rangers and volunteers. Which scene would you prefer to encounter at the summit of this world famous hike?
Consider taking the #ZionPledge found at https://www.nps.gov/zion/planyourvisit/zion-pledge.htm.
NPS Photos / Mike Young
Ten years ago, I took my first walk on the fire road above the North Oakland Regional Sports Center (Caldecott Field), where I saw fit to document an incipient landslide there. In June, standing on Skyline Boulevard, I noticed that the site was shrouded in black plastic, a surefire sign of a landslide. Passing by again last week, I noticed a change and made the time to visit. [ 302 more words ]
https://oaklandgeology.wordpress.com/…/landslide-update-fr…/
Hiram Thorn took it upon himself in 1853 to build a road over the Coast Range hills from today's Montclair to his redwood mill, which was either at the present site of Canyon or farther downstream where the former town of Pinehurst once sat. Thorn's Road was a toll road for a long time, connecting Oakland to the Moraga Valley agricultural hinterland and beyond. [ 993 more words ]
https://oaklandgeology.wordpress.com/…/tracing-the-old-tho…/
About Geology shared a photo.
VOG damaged gate locks, Mauna Loa
North and South America are such similar continents, but N American rivers are much smaller than S America's Amazon. How come? The answer is, we used to have one. A fascinating article from Earth magazine.
After a visit five years ago, I had high praise for Elverton Drive: "From end to end, it offers the best exposures anywhere of the Claremont chert." This stuff, as seen a few weeks ago during a return visit. Those of you who've followed along know the amazing striped chert of the Claremont Shale, which crops out in a belt from Claremont Canyon along a couple miles of Skyline Ridge to Huckleberry Botanical Preserve and beyond in the hinterland. [ 389 more words ]
https://oaklandgeology.wordpress.com/…/…/an-elverton-update/
This house in Piedmont caught my eye not long ago. Homeowners who live in conspicuous places do their neighborhoods a service by making their properties shine. I appreciated the care the owners of this home displayed not just in their plantings, but also in their choice of rocks. The site (110 Scenic Avenue) is in the middle of the block of Franciscan sandstone that underlies most of Piedmont and some adjacent parts of Oakland. [ 168 more words ]
https://oaklandgeology.wordpress.com/…/franciscan-landscap…/
A paper I read last week led me a long way in an interesting direction that started in El Cerrito, just up the ridgetop from Oakland, at the property fondly known as the Mira Vista Golf Course (restored in 2011 to its original glory and rechristened with its original name, the Berkeley Country Club). I first visited Mira Vista in 1999 to see the Hayward fault, which runs through the fairways and helps give the land its picturesque form. [ 626 more words ]
https://oaklandgeology.wordpress.com/…/when-did-everything…/
In 1914, UC Berkeley professor Andrew Lawson published the first decent geologic map of our area, the San Francisco Folio of the Geologic Atlas of the United States. That's where the Oakland Conglomerate got its name. But while that fine rock unit lives on in name, the concept it represents has changed. Let's look at a hundred years of progress in geologic mapping the area just west of Redwood Peak, the heart of the Oakland Conglomerate. [ 566 more words ]
https://oaklandgeology.wordpress.com/…/oakland-geology-ram…/
In my last post I described the spectrum of waste to be seen around the landscape. Piles of garbage are easy to see and judge as litter. Bones and downed trees are natural, but for citydwellers it takes an effort not to wish them removed. Then there are all the things on the spectrum of art, like these amaryllis bulbs donated to undeveloped Knowland Park. [ 319 more words ]
https://oaklandgeology.wordpress.com/…/the-human-presence-…/
The litter on the land falls along a spectrum. This disembodied deer hoof does not qualify as litter because, as far as I know, a human didn't leave it on this abandoned, overgrown fire road. I felt no obligation to do anything more than pause and contemplate it. At the opposite end of the spectrum is this spectacle just off Pinehurst Road on well-posted watershed land. [ 375 more words ]
https://oaklandgeology.wordpress.com/…/the-litter-spectrum…/
About Geology shared a post.
Excellent interview with Dr. Lucy Jones, a scientist I've long admired. Her new book "The Big Ones" is on my reading table.
Walking along the paved trail north of Inspiration Point, I was brought up short by a splendid outcrop of conglomerate. It's strongly reminiscent of the Orinda Formation conglomerate exposed to the south, in Sibley Volcanic Preserve and along Route 24 east of the Caldecott Tunnel. Naturally I fired up the geologic map (I keep USGS map MF-2342 on my tablet) to see how the locality is mapped. [ 451 more words ]
https://oaklandgeology.wordpress.com/…/how-useful-is-the-o…/
