I am only a thousand yards or so above sea-level.

I am in the "foot-hills" of the Northern Andes.
How sudden is this change! It is less than an hour since I parted from the plains below, and yet the surface-aspect around me is like that of another land.

I halt in a wild spot, and survey it with eyes that wander and wonder.

The leaf is less broad, the foliage less dense, the jungle more open.

There are ridges whose sides are nearly naked of tree-timber.