4:04 Ward — Geology of the Little Colorado Valley. 



salt* and gypsum, tending on exposure to assume the character 

 of nearly homogeneous marls and to form low ridges, but- 

 tresses and even isolated knolls or buttes, at the bases of cliffs 

 and in eroded valleys. The gypsum often forms thin sheets 

 which appear as fine white lines and which do not follow the 

 planes of stratification but cross the beds irregularly and also 

 cross one another, giving the exposures a peculiar striped 

 appearance. 



Between these beds of shale there occur, usually at more 

 than one horizon, brown sandstones. These are more or less 

 argillaceous and their exposed faces do not present sharp angles 

 but have rounded forms, due in the main to the influence of winds 

 which wear off the jagged appearance but do not tend to form 

 chimneys or assume fantastic shapes. These sandstone ledges, 

 which are very uniform in composition, sometimes have a 

 thickness of 100 feet or more, though such heavy beds are 

 usually interrupted by several layers of the shale. 



Toward the lower part of the Moencopie beds the shales 

 gradually become calcareous and there is in nearly all good 

 exposures a horizon of white impure limestone, well laminated 

 in its central portion, but becoming very thin and hard below 

 and finally passing either into the typical shale or into homo- 

 geneous marls. The extreme upper and also the extreme 

 lower portions of the Moencopie beds always consist, so far as 

 observed, of the typical dark brown argillaceous shale, and the 

 whole series, wherever the contact can be found, always rests 

 in marked unconformity upon the underlying Paleozoic rock 

 (Upper Aubrey). 



* An artesian well was bored at Adamana on the Santa Fe Pacific railroad, 

 eight miles north of the Petrified Forest and in the valley of the Rio Puerco. 

 At a depth of 305 feet water was struck which had sufficient force to rise 19 

 feet above the surface and discharge 25 gallons per minute. The water was 

 very salt, reported at 3 per cent-chloride of sodium, so as to be wholly unfit for 

 any use. ' Mr. James Swainson, in charge of the work, which was done by the 

 American Well Works of Aurora, 111., was good enough to send me the "log" 

 (record of boring), which is as follows : 

 v Feet. 



Surface sand and adobe 55 



Sandstone -- — 3 



Cement gravel .- -- 1 



Sandstone 29 



Water at 88 feet only slightly salt. 



Sandstone 20 



Brown shale 43 



Red shale - - 49 



Hard brown and blue shale.. - 5 



Red shale 70 



Sandstone . _ — 10 



Hard brown shale - 20 



Intensely salt water at 305 



The lower 200 feet of this section clearly belong to the Moencopie beds. 



