RECONNOISSANCE OF THE LYON NITRATE PROSPECT. 



general. The section on both sides of the point is essentially the same 

 (the dip being insignificant) and is as follows : 



1. Limestones and sandstones of the usual series, not examined in detail about 



200 feet. 



2. Hard arenaceous limestone, honeycombed with many small cavities 1 inch to 



2 inches in diameter and containing crusts of crystalline calcite 1 to 3 feet. 



3. Soft, easily weathered calcareous sandstone 2 to 4 feet. 



4. Harder limestone, more calcareous than No. 3 1 to 3 feet. 



5. Arenaceous limestone, with soft, easily weathered spots, also showing a few of 



the cavities characteristic of No 1 5 to 10 feet. 



6. Hard oolitic limestone (exposed on the north side of the point only) 4 'feet. 



7. Talus. 



Parts of the section are shown in figures 3 and 4. 

 Thin sections from specimens of No. 5 and No. 6 have been pre- 

 pared and examined by Prof. J. C. Jones, of the Mackay Scho.ol of 



FIG. 3. View of nitrate-bearing exposure on north side of point, showing weathering into strata Nos. 3 



and 5 of the section. 



Mines. He reports that No. 5 is an arenaceous limestone with 

 rounded quartz grains 0.1 millimeter in diameter, forming about 25 

 per cent of the entire rock. Blotches of iron oxide occur irregularly 

 distributed through the specimen and some kaolin is also present. 

 The calcite occurs in part as a microcrystalline cement and in part 

 as crystalline grains of diameters .up to 0.3 millimeter. No. 6 is an 

 oolitic limestone with many rather angular quartz fragments usually 

 occurring as nuclei of the oolitic grains. Some of the calcite has 

 been recrystallizcd and serves as cement. The oolitic grains vary 

 from 0.1 millimeter to 0.2 millimeter in diameter. 



The visible nitrate occurs as a very thin efflorescence on the sur- 

 face of Nos. 3, 4, and 5 of the section. Nitrate can also be detected 



