| The Horquilla Limestone in Southern Arizona is the equivalent of the Naco Formation to the North in Gila County. | |
| *A marker for the Horquilla Limestone is this Chaetetes Coral |  |
*From the Southern Arizona Guidebook III
| The Horquilla Limestone in Southern Arizona is the equivalent of the Naco Formation to the North in Gila County. | |
| *A marker for the Horquilla Limestone is this Chaetetes Coral | |
*From the Southern Arizona Guidebook III