258 ' THE JOURNAL OF GEOLOGY. 



7. Clay shales and sandstones, the latter sometimes white, all plant bearing, 

 much comminuted vegetable matter, matted beds of swamp plants, and 

 well-preserved dicotyledonous leaves of Dakota types, determinable. . . id feet 

 6. Black clay full of carbonaceous matter, with locally six inches of impure 



coal 4 feet 



5. Quarry sandstone, massive, light pink, soft, weathering iron-brown 60 feet 



4. Soft yellowish and reddish sandstones 100 feet 



3. Drab-colored clays with carbonized vegetable matter and gypsum crystals, 



interbedded with yellow sandstones 30 feet 



2. Soft yellow and reddish sandstones with some clay layers 60 feet 



Jurassic. 

 I. Olive gray, drab or bluish clays with reddish and yellowish sandstones, to 

 base 



This section may be represented diagrammatically as follows : 



Fig. 4. — Section through Minnekahta Cafion. 



I. Jurassic. 



3. Equivalent of plant bed in Section No. I. 



4. (Upper portion). Equivalent of cycad bed in Section No. I. 



5. Quarry sandstone. 

 7. Dakota leaf bed. 



II. Fort Benton. 



It will be seen by a comparison of these sections that they 

 are in substantial agreement, although no effort was made to 

 make them so. The crest of the divide in section I represents 

 the Quarry sandstone of section II, which was probably consid- 

 erably thicker at this point, fifteen feet more being found, exclu- 

 sive of erosion, but these rocks were often much harder in section 

 I, and no quartzitic rocks were seen in the quarry. On account of 

 the debris thrown down from the quarry and other obstructions, 

 it was not possible to examine the next member below with as 

 much care as was desirable in view of the fact that it seems to 

 be the equivalent of the cycad and fossil forest horizon of section 



