Erratics--from our blog

There is something really wonderful about walking through the Sierra and coming face to face with a massive boulder that looks as if it has been delicately placed there by the hand of God. The one in this photo was on top of a bare granite ridge overlooking Spicer Reservoir, and is about ten feet in diameter. I can't imagine how much it must weigh.

http://sites.google.com/site/backpackthesierra/home/our-blog?offset=0

You might think that it had rolled here from somewhere else---but there's nowhere else to roll from. It was on top of the ridge--and it was all downhill from there. Nope, it was dropped on top of the ridge by a glacier that picked it up miles away and carried it this far. And when the glacier finally melted, this massive boulder was let down easy--delicately balanced on top of the ridge for all eternity--or least the foreseeable future.

The name for these rocks is "erratics," meaning that they don't always make sense in relationship to their surroundings. Sometime they are of a complete different geologic make-up, and only the slow glacial train can account for their location.

But I also think of them as iconoclasts--a bit like us backpackers. We often march to a slighlty different drumbeat, and find ourselves where few have ever gone before. Or at least we like to think of ourselves that way. And much like the glaciers, we aren't exactly speed demons. With the speed at which we hike, it takes us a long time to get anywhere, too.

So we hike for hours, cover a few miles, and the sit down on top of a ridge, or along a stream, and rest for a while.

Just call us erratics.

there are some impressive erratics in that area. Closer to Lake Alpine I have camped under the edge of a 25' diameter erratic.
Jim

Now if the slide marks over alkali flats by rocks can be explained.

are those the death valley rocks that move miles?

i saw a show that led to believe its mositure freezing in the late hours providing a decent surface for the rocks to be blown by the 100 mph winds

Or maybe it's just Jimshaw, pushing them around, chuckling to himself about the crack-brained theory some nimrod scientist will come up with to explain how it happened.

I've wondered if it was the wind too, but the marks aren't necessarily in the right direction. Maybe the centrifugal force of the earth spinning. I see it in Nevada also, that's why I mentioned alkali flats, since I spent part of my youth there and young adulthood.

I saw a show a short while ago on the discovery channel or similar that did a good deal of testing on rock trails on the flats.

They actually took a good amount of soil from the surface of death valley, as well as several rocks which exhibited trails, and placed them all in a wind tunnel.

They simulated the usual wind levels the valley sees and concluded that on dry soil, the rocks won't really move. They moistened the soil slightly though, mimicking the brief rains they get on rare occasions, and the rocks made identical tracks through the soil, even replicating the erratic paths often seen. The amorphous shapes directed the rocks in different directions in a sustained wind from one direction...which I thought was the most interesting part.

Mystery solved!

yes i believe that was the show i saw as well...

@ OP oh and BTW i like your blog...

what camera do you use? and do you carry it in your pack, or leave it hanging?

Thanks Mark!

It's a new camera now. Until last year we had an old Fujifilm. BUt this one is a Canon Powershot SD 780 IS. Tiny little thing (hey, this is the UL backpacking board, right?)with a very big view screen. And I wear it in a little case that fits on my belt--you can see it in some of our photos. It's the perfect reason to stop any time the trail gets steep...because I have to take a photo!

it takes some nice shots...I have a olympus d620 so i am envious of any hipbeltable camera i suppose...but i love the detail i capture as well...as of late tho it seems the new pocket sizes are getting just as good