C. R. Keyes — Triassic Sy stein in New Mexico. 429 



latter it has yielded none at all. We have here as well as 

 there only an arbitrary provisional horizon for its base, and we 

 are if possible still more uncertain where to assign its summit. 

 The paleontological doctors disagree, and who therefore shall 

 decide % It all hinges upon the question whether the Jurassic 

 system has any representatives in this region. If not, then the 

 summit of the Trias can be established at once. But if the 

 upper portion of the enormous series of sandstones and 

 gypsum beds which lies between the Shinarump conglomerate 

 and the lower Cretaceous sandstone is Jurassic, the problem 

 must wait for a solution."* 



Of the Zuni section of the Triassic system it may be that 

 only the lower portion is represented east of the Rio Grande. 

 The upper part of this section has been regarded as belonging 

 to the Jurassic age; but until fuller data are obtained it does 

 not appear advisable to recognize the Jurassic system in this 

 part of the country. For the present, at least, all of this part 

 of the sequence will be considered as a portion of the Triassic 

 succession. 



New Mexico School of Mines, 

 Socorro, New Mexico. 



•U. S. Geol. Sur., 6th Ann. Kept., p. 135, 1886. 



Am. Jour. Scl— Fourth Series, Yol. XX, No. 120. — December, 1905. 

 30 



