Little Colorado Valley, Arizona. 



499 



Reservation. This erosion surface is also shown along the 

 Lower Little Colorado at a number of points. 



At Al Ranch in Warner Wash, the lower parts of the can- 

 yon wall are formed of chocolate and brown shales essentially 

 identical with the Moencopie exposures at Holbrook and else- 

 where along the Little Colorado River. The top of the wall 

 consists of 30 * feet of coarse conglomerate; between these 



Fig. 4. 



Fig. 4. The upper half of the Moencopie formation, five miles below 

 Tanner's Crossing. 



diverse lithologic units is a marked unconformity. Immedi- 

 ately at the contact the section is as follows : 



1. Shinarump conglomerate. Coarse to very coarse 



sandstone and conglomerate with pebbles 1-4 

 inches in diameter arranged as lenses and stringers 

 or embedded as individuals. Many pebbles are 

 rounded, some have lost only their salient angles. 

 About To per cent consist of white, grey, and red 

 quartzite, the remainder being quartz, chert, and 

 limestone. The stratum is cross-bedded and banded 

 grey and red on cross-bedding laminae. Fragments 

 of petrified wood, including logs, are common, and 

 teeth and bones occur in the upper part 30 feet 



2. Unconformity. Wavy surface with troughs 3 inches 



to 3 feet below crest. Large pebbles and petrified 

 logs in base of Shinarump conglomerate lie directly 

 upon Xo. 3. The plane of unconformity was 

 mapped at two points (figs. 5 and 6). 



