This trail head is about 12 miles west of Cortez, CO on County Road G. The old East Rock Creek loop has a renamed side loop that is the new East Rock Creek Trail. It circles around the East Fork Canyon and connects back to the Sand Canyon trail head for about a 7.0 mile hike.
At the trail head, the Castle Rock formation towers over the area. There is a large Ancestral Pueblo ruins site arrayed around Castle Rock and a small arch in the upper west corner. A large section of intact wall is visible on the back side of Castle Rock.
The south connecting trail segment features at least four small ruins sites. Three are associated with alcoves but one wall section appears to be sitting on top of the mesa, something of a penthouse location. At the 2.5 mile post the new East Rock Creek Trail continues north while the old route connecting trail turns back east. (Pictures of the ruins along the connection loop are on the Old System post.)
About one mile further down the East Rock Creek loop, a large arch appears on the right. It is possible to climb up closer and see blue sky through the arch. This large arch doesn't seem to get much attention despite being a major feature.
Toward the last segments of the hike there is another formenrly unnamed side loop, in 2011 named the Rock Creek Trail, that goes around the West Fork of Rock Creek. This is another option in the Sand Canyon Trail system.
The slick rock option is more interesting for hikers, giving better views and variety of terrain. It took me 3:30 hours to walk the East Rock Creek Trail route.