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 highest point in the US is Mount McKinley. the elevation is 20,321 feet high. Badwater in Death Valley's Mojave Desert of California is 282 feet below sea level.