Subdivisions. The Ordovician is the second period of the Paleozoic era. The Ordovician began after the end of a series of extinction events known as the Ordovician-Silurian extinction events which ended around 488 mya.
As a state highpointer, Humphrey's Peak in Arizona was on my bucket list. The trailhead was easy to find. The trail itself was not well maintained and rather rocky, which wasn't too bad going up, but required a lot of caution descending to protect your knees.
Distance from Phoenix: 144 miles north; two-hour drive. Why it made our list: Flagstaff is home to Humphreys Peak, the highest point in AZ and one of the few places to ski or snowboard in the state. Yes, it snows in Arizona. The High Country gets about 110-inches of the white stuff each year.