9-23-2016 Flagstaff, Arizona

Walnut Canyon National Monument, located east of Flagstaff, is lined with limestone cliffs and blanketed with trees, shrubs and other plants.

Over millions of years, flowing water eroded the softer rock layers of the cliffs creating shallow caves and overhangs.

We hiked a trail to an "island" of limestone in the center of the canyon.

Here we saw the overhangs created by erosion and some of the homes built by the Sinagua people  from 1100 to 1250 AD.

Rooms on the island have been restored, but there are many other cliff dwellings in the valley that have not been excavated.

Plant life clings tenaciously to the limestone cliffs.