They may include impassable mountain ranges, oceans, or vast deserts.

The ecosystems included several ice ages, tropical oceans, and a massive volcanic eruption.

Research station sites might include outer space (such as the International Space Station) and oceans.

"Commons" can include the atmosphere, oceans, rivers, fish stocks, national parks, advertising, and even parking meters.

It has a wide variety of responsibilities, this include the protection of the nation's natural resources: water, oceans, minerals, forests and jungles.

Natural sources include wetlands, swamps and marshes, termites, and oceans.

Focal topic areas include oceans, forestry, and agriculture.

The terrain types included plains, forest, marsh, mountains, hills, lakes, oceans, and wastes.

Subjects of the prints include fishing, oceans and whaling.

Waterways can include rivers, lakes, seas, oceans, and canals.