These ditches had to be deeper than old layers of leaves and roots, which caught fire because there has been so little rain.

And the oldest layer may not be the most accessible or even the most interesting.

If a third roof is needed, both old layers must be removed.

Usually, the older layer was exposed to erosion for some time before deposition of the younger.

But in any case nothing of the old layer that is not present in S was ever to reappear.

The old layers stretch deep into the heart of the planet.

The evidence comes from the oldest layers of Antarctic ice ever sampled.

As molten magma, it pushed between older layers of rock.

In claws, this results in an old layer, and it breaks off.

Located near Dushak, its oldest layers are dated to around 5,000 years ago.