MOOK. STUDY OF THE 3I0RRIS0N FORMAT! OK 



75 



Fig. 29. — Morrison formation south of Grand Junction, Colorado, looking north. 



are especially characteristic of the lower portion of the formation, but 

 heavy beds occur at intervals up to the top. A bed of limestone 2 feet 

 thick is also present in the lower portion. The following section was 

 measured by the writer in 1914: 



Section of McElmo Formation near Mack, Colorado 



Feet 



33. Dark, arkosic sandstone, taken as base of the "Dakota" 2 



32. Clay 34 e. 



31. Sandstone 3 



30. Covered 5 



29. Cross-bedded white sandstone 11 



28. Clay 40 



27. Cross-bedded white sandstone 11 



26. Clay 9 



25. Lumpy clay 1 



24. Variegated clays 52 



23. "White sandstone of varying size of grain 3 



22. Green sandstone, in places conglomeratic 2 



21. Clay, greenish at top 16 



20. 1). Sandstone 3 



a. White clay 9 



