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.
The San Francisco Peaks are composed of six peaks, including the four highest in Arizona: Humphreys Peak, 12,637 feet (3,851 m), Agassiz Peak, 12,356 feet (3,766 m), Fremont Peak, 11,969 feet (3,648 m), Aubineau Peak, 11,838 feet (3,608 m), Rees Peak, 11,474 feet (3,497 m), and Doyle Peak, 11,460 feet (3,493 m).