The smell of wild brush.
In the canyon the world is dry. Brown brush, wild, tough, strong, alive but bone dry. Dotted with gopher holes and the tracks of animals with small toes; blown with the strange fine dirt from the trails, so fine it's like powder.
There are trees at the bottom, marking the course of a stagnant stream fed by runoff. Dry trees, strong, stubborn, but always brown, except beneath them in the cooler air where smaller ones shelter. Even in summer it's cool there, and dark; and there's a new smell, fetid, the smell of life run amok in slimy green pools with polliwogs and the croaking of toads.
I killed a bird once and regretted it ever after.
Here the trees are green, deeply, evergreens, pines. Foreign, foreign, false.