泛滥之谜 19

The soil here is volcanic.

That means it contains a rich cocktail of nutrients.

It was soil as fertile as this which nurtured the crops of Ancient Egypt.

With the plentiful rain and intense mountain sunshine, the grass here grows fast.

This explains why these highlands can support such huge numbers of animals.

The rains are transforming the highlands in another way.

Night temperatures could be low enough to freeze any water in the ground.

As the ice expands, it breaks up the topsoil.

When the ice melts the next morning, the soil is left crumbled and fine.

Millions of nest-making rodents loosen the soil further.