Angeles Crest Highway
Angeles Crest Highway winds through the foothills into the San Gabriel Mountains and down into a corner of the Mojave, through the length of Angeles National Forest.
Its elevation ranges from around 3,000 feet to more than 8,000 feet, and it passes through chapparal, evergreen forest and true desert.
Look at the south-facing slopes on the north side of the road, and you'll notice the vegetation is scantier than on the other side, which faces north. In places there's even forest on one side of the road and desert on the other.
Also look at the exposed rock as you ascend. You'll see rusty, white, beige, gray and even blue-veined rock like on the left. These mountains are one of the most geologically complicated regions on Earth; their geology has never been completely described.
Most of the way, the road winds through chapparal, which is thicker and usually higher than coastal sage scrub, but it takes an experienced eye to see the difference. It's green in spring, but in summer and fall it's a depressing brown.
Watch out for the motorcyclists as you drive -- they love to see how fast they can take the twisting curves of the road.