Their landing was in a wild and lonely place, still well within the natural boundary of night.

They tend to follow the natural boundaries of the landscape.

Without natural boundaries to control development, Atlanta keeps growing - sometimes up, but mostly out.

"This is a conflict with no natural boundaries," he said.

But I would submit that a state tournament is the natural boundary for high school sports.

There are no natural boundaries except the rivers, and it is easy to get at the cities from north or south.

We must also remember that this is a conflict with no natural national boundaries.

The mountain range is a clearly defined unit having natural boundaries on all four sides.

Of course the natural boundaries are fluid in this area too.

The river acts as a natural boundary between the two nations.