The Grand Falls Overlook is located at a picnic area on the Navajo Indian Reservation. The road is graded dirt and should be fine for all vehicles except for when it is wet. There is no fee, but keep the area clean and all pets must be leashed so they don’t disturb the livestock.
Hazard warning: This location is adjacent to sheer cliffs. The river bed may be muddy and slippery. Strong currents in the river have pulled people over the falls.
The overlook is located on a basalt lava flow just west of the falls. From the western most picnic bench you can get a great view of the falls (and get the virtual geocache GCG7H0 which brought me here in the first place). 
The Grand Falls formed when lava flowed into the Little Colorado River channel about 20,000 years ago. The lava came from one or more of cinder cones and vents located a short way off to the southwest. The flow completely filled the river channel and continued a short way across the channel northeast. Some lava also flowed about 15.5 miles down the river channel.
Once filled, about 4 miles of the channel upstream of the lava dam was filled with sediment. The river found a new path around the edge of the flow and back to the original river channel. The once smooth slope of the lava flow down into the original channel has been eroded the back into the step-like 185 foot falls. Interestingly, much of the basalt in the bottom of the channel has not been eroded down.
There is typically little or no water flowing in the river, but in the spring and after rains, muddy water cascades down the falls.
Logging requirements:
Send me a note with :
- The text "GCZ5HV Grand Falls Earthcache" on the first line
- The geocaching names of the people in your group.
- E-mail the number of cinder cones that you think could have been the source of the lava flow.
- Guess at why the falls have the step-like appearance.
- Photos welcome.
The above information was compiled from the following sources:
- Duffield, Wendell and others, Multiple constraints on the age of a Pleistocene lava dam across the Little Colorado River at Grand Falls, Arizona, Geological Society of America Bulletin: Vol. 118, No. 3, pp. 421–429.
- Google Earth