Pre-Bliss rocks in the Van Horn region, Trans-Pecos Texas
— Rodger E. Denison

The Precambrian rocks exposed around Van Horn are unique among the scattered exposures between the Rocky Mountains and the Appalachians.

King and Flawn (1953) provided the basis for most of our understanding of these rocks. Wasserburg and others (1962), Denison and Hetherington (1969), and Denison and others (1971) have provided a reconnaissance geochronologic framework that is requisite in understanding Precambrian activity. The relationship of these Precambrian rocks to those exposed in the general area and to those penetrated in the subsurface has been discussed by Denison and Hetherington (fig. 1).