But it was too stoney and full of cactus on top.

Why, then, do rocks look and feel solid and hard and impenetrable?

And shale is not quite completely competent rock.

The term rock formation used in the second report is susceptible to the interpretation that the formation is made up of hard and solid rock.

Oh, he's the Rock the Rock of Gibraltar.

Rocks n Diamonds

In this case, chimpanzees teaching each other how to crack nuts with rocks.

Like a rock.

an inlet among the rocks, many rocks that... she had never realized,

This efficiency is, in turn, dependent on local geological conditions such as the hardness and water content of the rock surrounding the explosion.

They're clinging to a rock face and actually scraping bacteria off that rock face.

You're climbing on little dimples and nubbins in the rock.

Some rocks and some finches.

Decorative Rock

The rock that Kanzi is using is extremely hard and ideal for stone tool making, but difficult to handle, requiring great skill.

So it would seem the hardest, solidest, densest rock is really almost entirely empty space, broken only by tiny particles so widely spaced they shouldn't count.

The waves crashed against the rocks.

I looked down from the top into the rocks.

You hit the solid rock.

Here's a piece of limestone.

Not so fast. Wait a minute. Large rock...

He hit his head against a rock.

He hit his head against a rock.

Under a high rock on a ledge near Penistone Crag.

The very unusual Kaidun chondrite is a chondrite breccia consisting of a variety of highly oxidized and highly reduced lithologies.

A rock fell from above.

No water, rocky soil.

Didn't you see the rocks?

The Lord is my rock and my fortress.

So, that's just a rock in the hillside.

And as the sandstone weathers, new grains break free.

And it's just limestone, nothing really special about it.

On the trail we took just before we reached the limestone rocks.

The Lord is my rock!

After the limestone rocks, what?

You fell off the rocks?

If we had, our brains probably would perceive rocks as full of empty space. Rocks feel hard and impenetrable to our hands precisely because objects like rocks and hands cannot penetrate each other. It's therefore useful for our brains to construct notions like solidity and impenetrability, because such notions help us to navigate our bodies through the middle sized world in which we have to navigate.

There is a median point between tiny rock and gigantic rock, and in fact, if any of you have ever been to near Winslow, Arizona, there is a crater in the desert there that is so iconic that it is actually called Meteor Crater.

No water, rocky soil.

You bet what? I'll bet... he said he'd get off your rocks.

Get those wagons to the rocks.

Then we'd have solid bedrock on both banks.

Extra difficult. Extra hard.

This guy was breaking rocks with a hammer in the hot sunlight, but he just wanted to spend his life as a farmer.

The oldest rock on Earth is only 3.6 billion.