Mystery Photo For a Saturday

So, with no sense of scale or other clues, anyone want to try and explain/describe this surface? For certain people I know, the answer may be in three...two...one...

Just a bit of fun for a Saturday morning...

Three Roads Diverged...but why? A Saturday Mystery Photo

Three roads diverged in a green wood,
And sorry I could not travel all three
And be one traveler, long I stood
And looked down one as far as I could
To where it bent in the growth of trees;

Then took the other, as just as fair,
And having perhaps the better day,
Because it was grassy and wanted wear;
Though as for us the passing there
wouldn't be, for the fence that blocked our way;

And number three that morning lay
Betwixt a river cold and black.
I kept the second for another day!
And the third, there was no way,
I doubted if I should ever come back.

I shall be telling this with a sigh
Somewhere ages and ages hence:
Three roads diverged in a wood, and I—
I took the one most travelled by,
And that has made all the difference.

With very humble apologies to Robert Frost....

Three roads that once led to the same destination. Why did we take the middle? Highway 140 on the way to Yosemite.

A Saturday Night Mystery Photo

Back home from today's field study course in the western Sierra Nevada. The rock is marble of the late Paleozoic Calaveras Complex...what's going on here??