398 DESCRIPTIVE GEOLOGY. 



stances. Boiling the solution Math metallic tin gave not the slightest reaction 

 for titanic acid, — an important test, since titanic acid might be easily mis- 

 taken for zirconia. A specimen of the hornblendic gneiss irom Ogden 

 Canon, which was analyzed by Professor Robert Bunsen, gave the follow- 

 ing results : 



Silica. ...../ ^ . 74.95 



Alumina. 9.42 



Ferric oxide u ..... ^ . — •. 7.47 



Lime 1 .65 



Magnesia . 0.13 



Soda '- 4.05 



Potassa — ... — 2.02 



Water ..... . . . . , ^ 1.02 



100.71 



This rock is unusually low in the percentage of alumina present ; lower 

 than any other of the granites and crystalline schists that have been ana- 

 lyzed. On the other hand^ it is very high in ferric oxide. The amount of 

 soda present would indicate that it carried a very considerable proportion 

 of triclinic feldspar. 



In Ogden Canon, above this Archaean body, are exposed in section 

 the entire series of Palaeozoic strata, from the Cambrian up to near the top 

 of the Wahsatch limestone. The strike in the lower beds is about north 

 30° to 35° west, with a dip of 60° to 65° to the eastward. The Ute lime- 

 stone falls away gradually with less and less dip, until, near the well-defined 

 junction of the Ogden Quartzite, it stands at an angle of 40°. This dip 

 is preserved by the Ogden Quartzite and the lower beds of the Wahsatch 

 limestone, but the upper portion of the great belt of limestone gradually 

 assumes a lower angle, until, near the head of the canon, it forms high pre- 

 cipitous walls, with a gentle inclination to the eastward of 7^ to 9°. 



The Cambrian formation is represented by about 900 to 1,000 feet 

 of quartzite, overlaid by about 100 feet of siliceous and argillaceous shales, 

 which in their upper portion becpme calcareous. The quartzite is char- 

 acterized, especially in the lower beds, by great uniformity in lithologi- 



