Bridge 4 and more!!

Bridge four is the last of the ERA bridges. Look here and learn. Yes, Marge. There's always a quiz later.

More Brittlebush leaves. Photo by Ned Harris

If you ever find yourself lost in Sabino Canyon, you're carrying a magnet (to pick up magnetite from the sand), and are conveniently located near the creek and a Brittlebush, Bruce says: 

The fine hairs also make this leaf more boat-like, and it floats higher. One can put a pinch of magnetite in the boat, and the boat will rotate until it faces north. A field compass. Other leaves are not so accommodating.