Red Mountain
There are many cinder cones around Flagstaff, but not like this one. The eastern side has fallen away, making it great for exploring.
This hike was recommended in my "Hiking with Dogs" book, so after hiking a mile and a half to the mountain, I was surprised to find a seven foot high rock wall. I learned a couple things. First, Tahoe can climb up a ladder. Second, he cannot climb down one. In fact, he refused to even go near it. The only other option was climbing the steep cinder wall, and Tahoe was not interested in that either. Eventually, I ended up carrying an extremely reluctant 42 pound dog in my arms down the ladder.
The colorful volcanic rock walls had lots of cool juecos (or hoodoos as I call them).