Late Cambrian(?) to Late Ordovician rocks from the northern end of the Spring Mountains were deposited as part of a westward-thickening wedge in a cratonic margin paleotectonic setting on the eastern edge of the Cordilleran miogeocline. Lithologic units sampled include the Pogonip Group (311 m), the Eureka Quartzite (6 m), and the Ely Springs Dolomite (193 m). Twenty-two conodont bearing samples have clarified age relationships of these paleogeographically significant strata. Conodont faunas indicate these strata are age-correlative with other sections in the southern Great Basin. The Pogonip Group contains conodont taxa which range in age from Late Cambrian(?) through late Early Ordovician. Conodonts recovered from the Ely Springs Dolomite are Late Ordovician. The upper 96 m of this unit is completely barren of conodonts as is the Eureka Quartzite. The significance of this section is that it is the easternmost section with recognizable miogeoclinal lithologic units. The Eureka Quartzite does not exist to the east of this section; and the Ely Springs Dolomite is replaced by the Mountain Springs Formation of the same age.