42 



MESOZOIC FLORAS OF UNITED STATES. 



SECTIOX V.-^LEROVX WASH. 

 [PI. IV, I-K.] 



This section begins on tlie loft liank of the i-iver 

 about 5 miles above Obed, opposite St. Joseph. The 

 Carboniferous sandstones here come down to the river 

 bed. It passes over the ridge below the mouth of 

 Loi-oux Wash and follows the eastern slope of the 

 wash for a distance of 20 miles, passing through the 

 great amphitheaters of variegated marl buttes that I 

 have described as constituting the greatest develop- 

 ment that this formation attains. The section finally 

 cuts across the upper portion of the wash and passes 

 up the slopes beyond to a distance of 40 miles from 

 the river, where the mesas attain an elevation of over 

 6,000 feet above the sea. It embraces practically the 

 whole of the Trias. 



Description oj the sectio7> shown in fig. 5. 



1. ('ai'l)onifcious sandstone (tliickness unknown). Feet. 



2. Mooncopie formation 500 



3. Lithodendron member 700 



4. Variegated marls -IIX) 



5. Limestones and mortar beds 300 



6. Calcareous marls 200 



7. Orange-red sandstones 100 



8. Variegated sandstones 700 



9. Brown sandstones 200 



Total thickness 3, 100 



SECTION VI.— THE PETRIFIED FOREST. 



Little Coloraao 





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[PI. IV, L-M.] 



I have carried this section as far back on the 

 southwestern slope of the Little Colorado as I was able 

 to find any traces of the saliferous beds. The Carbonif- 

 erous sandstone occupies the northeastern slope of the 

 Pink Cliffs, and the section starts at an elevation above 

 the sea of nearly 6,000 feet. It passes through Woodruff Butte, which 

 is on the bank of the river, and thence on through the Petrified Forest 

 and over the mesa on which the Natural Bridge is situated. I have 



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