Dakota and adjacent Morrison and Lower Mancos stratigraphy (Cretaceous and Jurassic) in the Holy Ghost Spring quadrangle, land of pinchouts, Jemez and Zia Indian reservations, New Mexico
— Donald E. Owen, Charles T. Siemers, and Owen, Donald E., Jr.

The Holy Ghost Spring Quadrangle (HGSQ) is the most important area on the east flank of the San Juan Basin for understanding the complex pinchouts in the intertongued Dakota Sandstone-lower Mancos Shale. All of the following stratigraphic units were mapped and correlated across the quadrangle: Encinal Canyon Member, Clay Mesa Shale, Paguate Sandstone, Whitewater Arroyo Shale, Twowells Sandstone, Greenhorn Limestone, and Semilla Sandstone, which all pinch out in the quadrangle, and the Jackpile Sandstone, Oak Canyon Member, Cubero Sandstone, and Juana Lopez Member, which all extend completely across the quadrangle, each providing a stratigraphic datum to constrain the pinchouts.