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.
âº View larger image. Arrow shows highest point on the Moon, 10,786 meters (35,387 feet) above the mean radius. North is up, Sun elevation is 16Â° from the horizon, image 500 meters wide, from M133865651L,R mosaic. Credit: NASA/GSFC/Arizona State University.