60 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 



RED WALL GROUP. 



No. 12. Thickness not determined. Buffish-lavender, friable, fine 

 grained sandstone ; base not seen. 



GRAND CANON SECTION. 

 UPPER AUBREY GROUP. 



No. 1, 145 feet. Limestone and sandstone, not very thickly bedded. 



No. 2, 220 feet. Massive limestone, brecciated and cherty, and.weather- 

 ing in columnar forms. 



No. 3, 170 feet. Gypsum and gypsiferous sandstone, irregularly bedded, 

 contorted and broken, stained brown in patches. 



No. 4, 240 feet. Massive limestone. 



LOWER AUBREY GROUP. 



No. 5. Bright red sandstones, thinly and thickly bedded, very red, 

 weathering in long slopes. 



No. 6, 600 feet. Red and buff sandstones, heavily bedded, exhibiting 

 composite structure, (cross bedding,) with irregular and inconstant beds of 

 limestone. 



RED WALL GROUP. 



No. 7. Limestones and calciferous sandstones ; heavily bedded ; gray 

 and brown ; much chert in limestone ; chert red and vitreous ; sandstone 

 friable. 



No. 8, 800 feet. Massive granular limestone ; in some places cherty ; 

 sometimes running horizontally into thinly bedded rocks. 



No 9, a, 10 feet. Friable, greenish sandstones, b, 6 feet. Purple sand- 

 stones, thinning out in places; has the appearance of having been eroded. 



No. 10, 300 feet. Thinly bedded limestone, with layers and nodules of 

 chert. 



No. 11, 50 feet. Sandstones; gray and buff; sometimes mottled; 

 probably calciferous. 



No. 12, 100 feet. Heavily bedded limestone, with calciferous sand- 

 stones at summit. 



