Friday, November 20, 2015

Rock piles with holes

From Norman Muller:
I remembered seeing engravings of such a feature, and I am attaching them.  These two images come from a Smithsonian publication from the late 1800s

1 comment :

pwax said...

This gives me an opportunity to make a distinction. There are two kinds of "hollows" I encounter routinely.
- One kind is well built with vertical facing and and, occasionally, the hole is superficial to the pile.
- The other kind is where something inside collapsed leaving a dimple in the middle of the pile.

Of course there are many variations on the latter. For the former, well built holes, I am used to them being square, not as shown in Norman's illustrations.