38 



MESOZOIC FLORAS OF UNITED STATES. 



[PL IV, C-D.] 



This section begins some 5 or 6 miles below 

 the mouth of the Moencopie Wash, opposite the 

 upper end of the hmestone canyon. The rocks 

 dip away from the river from the first, and the section remains wholly 

 within the valley of the Moencopie, reaching the bed of it at a distance of 



iiiff 



Limestone Canyon 

 Coconino Point 



and lower in its horizon, until at last, some 12 miles below, the Paleozoic 

 limestones appear, and in the very narrow canyon suddenly formed at the 

 base of Coconino Point, which forms the eastern 



_ Id N U 



escarpment of the Colorado Plateau, the limestone 

 rocks rise to a height of 100 feet and constitute 

 the canyon proper. The section along the river 

 between these points was carefull}' worked out by 

 me. The most remarkable fact was that about 

 4 miles above the limestone canyon there occurs 

 a Paleozoic anticline as viewed from the bluffs, 

 the limestones rising to a height of about 90 feet 

 and again descending to the bed of the river, the 

 length of the anticline being about 2 miles. This 

 of course represents a spur of the Colorado Pla- 

 teau, running out parallel to it in a northeasterly 

 direction, which was cut through by the river. 

 This is shown in the following diagrammatic sec- 

 tion, 12 miles in length: 



Desa-iption of the section shoum in fig, 1. 



Feet. 



1. Carboniferous limestone 100 



2. Argillaceous shales and sandstones, Moencopie formation . 200 



3. Lithodendron member 125 



4. Trap 30 



Total thickness 45.5 



The above are the vertical measurements of 

 the beds as seen in the bluffs. Probably twice 

 that thickness of the Moencopie beds is repre- 

 sented, and only the base of the conglomerate 

 series is here exposed. 



SECTION II.— MOENCOPIE WASH. 



Moencopie Wash 



Tanners Crossing 



