H. E. Gregory — Shinarump Conglomerate. 435 



Permian (Moencopie) is marked at this locality by an uncon- 

 formity, immediately above which the Shinarump conglomerate 

 occurs with all its distinguishing features. 



The shales and sandstones below the Shinarump conglom- 

 erate are assigned to the Permian chiefly on the basis of collec- 

 tions of Walcott* in the Kanab valley, Utah. At this locality 

 fossils were obtained from impure limestones and arenaceous 

 shales in the midst of a series 854 feet in thickness, terminated 

 above by the unconformity marking the base of the Shinarump 

 conglomerate, and below by the upper limestone of the Aubrey 

 group (Kaibab limestone of Darton). Twenty-three genera 

 represented by thirty-four species and including Pentacrinus, 

 Mytiliis, Pleurophorus, Schisodus, Bakewellia, Pteria, 

 Lingula mytiloides, Discina nitida, RJiynchonella Uta, were 

 found to occur in the upper portion of. the strata. The lower 

 chocolate-colored limestone furnished specimens of Myalina, 

 Schizodus, Nucida, Aviculqpecten, Mttrchisonia, Naticopsis 

 and Goniatites. While fossils at numerous other localities 

 where the Permian is exposed are much to be desired, yet the 

 unmistakable evidence from Kanab taken in connection with 

 lithologic similarity and the unconformable position of these 

 beds below the Shinarump conglomerate, furnishes fairly satis- 

 factory determinations of age relationship. 



(3) The unconformity between the Permian (Moencopie) 

 and the Shinarump conglomerate has been recognized 

 repeatedly. Gilbert states : f 



" The Shinarump conglomerate, although remarkably persistent 

 for a conglomerate, thins out and disappears at a number of points, 

 and at the margins of its areas it is evident to the eye that it 

 occupies depressions of the surface on which it rests." 



Dutton remarks : \ 



"In the Permian, Trias, and Jura we find instances of those 

 peculiar unconformities by erosion without any unconformity of 

 dip in the beds. Perhaps the most widely spread occurrence of 

 this kind is the contact of the summit of the Permian with the 

 Shinarump conglomerate which forms the base of the Trias. 

 Wherever this horizon is exposed this unconformity is generally 

 manifest." 



Huntington§ notes the unconformity in a measured section 

 at Toquerville ; Walcott describes and figures the unconform- 

 ity between Paria and House Pock Springs, Utah,|| where a 



*This Journal, vol. xx, pp. 221-25, 1880. 

 f Geology of the Henry Mountains, p. 8. 

 JU. S. Geol. Surv., Monograph II, p. 211. 

 §Bull. Geol. Soc. Am., xviii, p. 383, 1907. 

 I Ibid., i, pp. 63-64, 1890. 



