The Deem Hills are composed mostly of ancient Precambrian granite and other Tertiary age volcanic rocks, dating from nearly 2 billion years ago. During this time, rock fractures appeared where dark lava called basalt flowed and gave Deem Hills its characteristic black rock formations. In fact, much of this hilly area west of I-17 is comprised of the same basalt rock. A new trail in the Deem Hills trail system is named Basalt Trail. The name Deem Hills can be traced back to 1922. At that time, Dennis and Carl Deem began homesteading 160 acres southwest of the hills.
Deem Hills makes up almost 1,000 acres of Arizona Upland vegetation. The area showcases a variety of vegetation such as saguaros, barrel cacti, brittlebush, hackberry, ocotillo, palo verde trees, creosote, globe mallow, and buckhorn cholla; just to name a few.
The Deem Hills Circumference trail at 5.73 miles traverses the entire recreation area and commands excellent views of the Phoenix area, the Hedgepeth Hills to the south, and the Hieroglyphic and Bradshaw Mountains to the north. It also connects the trailhead parking lots at 39th Ave. and Pinnacle Vista and Deem Hills Community Park to the west.
Once on the circumference trail, you’ll find easy access to the Ridgeline trail which runs 1.45 miles and is the highest trail in elevation in the system. It has excellent views to the north and west including of Ludden Mountain. The Ridgeline Trail can be strenuous so exercise caution. The Palisade trail at 1.53 miles utilizes the water reservoir road to the east as it twists and turns through the interior. The shortest trail, Basalt connects to the Ridgeline, Palisade, and Circumference trails providing quick shortcuts to each at only .64 miles in length.