I02 WHITMAN CROSS 



southwestern Utah, a few fragments of lameUibranch shells were 

 found by Howell. These were too imperfect for determination. 



The Shinarump Group. — The comprehensive term "Shinarump 

 Group" was proposed by Powell in 1876, in his Geology of the Uinta 

 Mountains, for all the strata known to him between the upper Aubrey 

 limestones and the Vermilion Cliff sandstone. Its Triassic age is 

 assumed. The group is not described in much detail, the following 

 section made by Powell "along the course of the Kanab in the winter 

 of 1 871" being the most complete statement given. 



SECTION OF THE SHINARUMP GROUP, POWELL 



Top FEET 



11. Bad-land sandstones, rapidly disintegrating; argillaceous; weathering 



in variegated hills ......... 800 



12. Conglomerate .......... 80 



13. Red bad-land sandstone; very friable, with much gypsum . -195 



14. Greenish-gray bad-land sandstone, with much gypsum, and rapidly 

 disintegrating . . . . . . . . . . 100 



15. Compact gray sandstone ........ 8 



16. Red sandstones and arenaceous shales; gypsum in seams and joints . 300 



17. Red and brown sandstone; rather thinly bedded, with many ripple 

 marks ........... 250 



18. Conglomerate with angular and rounded fragments of limestone in a 

 matrix of calciferous sand ........ 50 



1.783 



The conglomerate eight hundred feet below the top of the group 

 is evidently the one elsewhere designated Shinarump conglomerate. 

 Powell gives no hint that an unconformity had been noted by Gilbert 

 beneath that horizon, but he repeatedly refers to the one at the base. 

 The upper and lower parts of the group are described in very similar 

 terms, and fossil wood is said to characterize the whole group. It is 

 pointed out that, "The Shinarump conglomerate is usually very hard, 

 and weathers in such a manner as to form hogbacks or cliffs, and the 

 softer gypsiferous beds above, when carried away by rains, leave 

 behind fragments of this silicified wood," etc. 



It is evident that Powell did not suppose that his Shinarump 

 Group contained Permian or other pre-Triassic beds. Neither he 

 nor any other early observer commented upon the fact that if the 

 Shinarump conglomerate contained worn pebbles of fossil wood 



