Describes the inhospitable habitats of snow and ice. Mount Rainier in America is an example of such a place: there is no vegetation, therefore no herbivores and thus no carnivores. However, beneath its frosty surface, algae grow and some insects, such as ladybirds visit the slopes. Africa’s mountains are permanently snow-covered, and beneath peaks such as Kilimanjaro and Mount Kenya, there are communities of plants and animals.
Begins in northern Norway, 500 kilometres north of the Arctic Circle. Here, there is only just enough light for the pine trees to survive, but it is extremely cold during the winter. Pine cone seeds provide one of the few foods available at this time of year, and large herbivores such as the moose must also rely on their fat reserves.
Visits the world's deepest valley: the Kali Gandaki river in the Himalayas. Its temperatures range from those of the tropics in its lower reaches to that of the poles higher up. It therefore shows how creatures become adapted to living in certain environments.
Explores the grasses which are present all over the world. Grass sustains huge numbers of creatures the world over, particularly in the African grasslands, where huge numbers of savannah animals have made their homes.
Starts in the Sahara, where the highest land temperatures have been recorded. Rock paintings depict creatures such as giraffes and antelopes, suggesting that at one point there was enough vegetation to support them.
Attenborough describes the course the Amazon, starting high up in the Andes of Peru, whose streams flow into the great river. Young rivers are by nature vigorous and dangerous: they flow fast and form rapids, thick with mud and sediment.
Details coastal environments and the effect of tides, of which the highest can be found in the Bay of Fundy in North America. In places, erosion is causing the land to retreat, while in others — such as the tropics — the expansion of mangroves causes it to advance.