Archive for the ‘cemetery knockers’ Category

Knockers south

26 February 2009

knockers

Now is a good time to post this picture taken last June, if only to remind myself that summer will return. This is looking up from Moraga Road, near the Piedmont maintenance yard, at the open land south of Mountain View Cemetery, and of course we are looking once again at knockers.

It’s a scramble to reach those rocks, but they promise the peace of a well-earned private perch with a great view. One or two of the rocks on this slope are appreciated by the local youth, to judge by the paint and other signs. Having been such a youth myself, I can’t object.

Just up the road from this spot is a sweet, discreet trail connecting to Abbott Way.

trail

Knocker nine

22 October 2008

knocker 9

I don’t know why I call this knocker nine, since the last set of Mountain View Cemetery knockers I posted should be number 8 through 11. But I can be inconsistent in my domain, and besides I think it just looks like knocker nine. This mini-outcrop in the Franciscan mélange is on Piedmont town land, on the hillside above the skateboard park south of the cemetery. The rocks are no respecters of property lines or jurisdictions.

I’m headed out of town for a few days, so talk amongst yourselves if you like. I’ll be in Las Vegas and enroute by car, taking a loop down into deepest Imperial County.

Northside knockers

18 September 2008

northside knockers

I made a brief reconnaissance of the land just north of Mountain View Cemetery last week and captured a few more knockers. Poison oak is abundant here, I should report. It’s a lovely thing to see pristine outcrops, although the geologist in me wished for a handy rock hammer. In its absence, I can only say that this and the next knocker looked like typical sandstone or greenstone from the Franciscan mélange making up the area.

northside knockers

This next knocker is definitely chert of the high-grade type found elsewhere in Upper Rockridge. Notice that it supports less vegetation, being poorer in nutrients.

northside knockers

My reconnaissance was brief because the area is undergoing development, and while I didn’t notice a no-trespassing sign where I passed the fence I felt the need for discretion. The best knocker of the area, unfortunately, is under attack (click full size):

northside knockers

The upper body of red chert is still living bedrock while the nearer pile is loose pieces of it. I don’t know what is being planned for the area, but the chert would look nice in a fairway, or left in shabby gentility like some of its siblings.

Knocker 7

30 June 2008

knocker

This is the last knocker I’ve documented in Mountain View Cemetery. It’s by the second road down from the one leading to the top, on the uphill side. It looks like the gray sandstone that makes up much of the Franciscan Complex.

The bulk of the upper cemetery is underlain by Franciscan mélange, a mix of rock types in a weak, shaly matrix. You never see the matrix except temporarily in roadcuts; it quickly crumbles into soil and becomes covered with vegetation. The chunks of other rock types emerge from this soil, and that’s what knockers are.

There are other exposures of bedrock along some of the cemetery roads, but I don’t count them as knockers. And there are several knockers in the off-limits land at the very top of the cemetery. Maybe I’ll document some of them next. And I really should do one more concerted search to see if I’ve missed any.

The big set of knockers, Mountain View Cemetery

4 June 2008

biggest knocker

Just below the highest hill in the cemetery, across a flat space south of the utility yard, is the best bedrock outcrop in the whole Mountain View property. This shot is from the south end looking toward the utility yard; red chert is in the foreground and other Franciscan rocks lie behind. I suspect that it was once a free-standing ridge that has been filled in on the east (uphill) side. The west side is a wall of trees, some of them growing right out of the rock, that hides everything pretty well.

Rocks of the Franciscan Complex, to remind everyone, include red chert, light-gray coarse-grained sandstone, dark shale, and dark volcanic rocks with various degrees of metamorphism. The volcanic rocks came first, formed at a deep-sea spreading ridge. Deep-sea ooze made of siliceous microfossils settled on the volcanics and became the chert. As the whole seafloor assemblage approached North America, sediment from the continent cascaded down submarine canyons and later turned to sandstone and shale.

All of these entered a tectonic subduction zone, marked by a deep-sea trench like those off Japan today, and the whole assemblage was squeezed, heat-treated, crumpled and plastered against the prow of the North American continent. The different rock types, ranging in age between about 150 million and 60 million years (Jurassic to Paleogene), were churned into an intricate mixture called mélange. Chunks of the harder rocks float in a scaly matrix of soft shale and tend to emerge above ground as the rocks erode into soil. Those chunks, not quite bedrock and not quite boulders, are what generations of California geologists have called “knockers.”

Later, sideways movements along the wide San Andreas fault complex tore up and rearranged this complex of rocks even further. Today Franciscan mélange is found in the Coast Range from south of San Luis Obispo all the way up to Cape Mendocino.


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