| Horquilla Limestone in the Tucson Mountains |  |
| Horquilla Limestone near Vail |  |
| The Horquilla Limestone in Southern Arizona is the equivalent of the Naco Formation to the North in Graham County. This is an outcrop of Horquilla (Naco) limestone near the Gila River just north of Winkleman Arizona |  |
| *A marker for the Horquilla Limestone is this Chaetetes Coral |  |
*From the Southern Arizona Guidebook III