KNOPF : ANDALUSITE MASS 549 



In a further note another absorption glass will be described 

 for use with a tungsten-filament pyrometer lamp: a glass such 

 that its transmission requires an invariance of A with for all 

 practical purposes, taking account of the loss of light at lens sur- 

 faces and the emissivity of tungsten. 



GEOLOGY. — An andalusite mass in the pre-Cambrian of the 

 Inyo Range, California. 1 Adolph Knopf, Geological Sur- 

 vey. 



The andalusite mass here described is in southern Mono 

 County, California, 4 miles east of Milner station on the Nevada 

 and California Railroad. It is in the northern part of the Inyo 

 Range, or as this part of the range is known locally, the White 

 Mountains, and is at an altitude of 7500 feet, about 3000 above 

 the floor of Owens Valley. 



GENERAL GEOLOGY 



The rocks exposed along the trail that leads from the base of 

 the range to the andalusite mass consist largely of argillite, 

 more or less slaty, and schistose conglomerate. They form 

 a belt more than 10,000 feet wide, of which the conglomerate 

 is roughly estimated to make up one-third. The strata stand 

 at high angles, generally vertical, so that their thickness is 

 roughly measured by the width of the belt, but they have prob- 

 ably been repeated by faulting. 



The conglomerates are composed mainly of fragments of 

 fine-grained quartzite. Many of the pebbles, which range up 

 to 12 inches long, are well rounded, but the smaller pebbles 

 are generally angular. Pockets and irregular lenses of con- 

 glomerate are irregularly intercalated in argillitic strata, and 

 the pebbles in these intercalated lenses are unsorted and un- 

 shingled, the longer axes of contiguous pebbles commonly stand- 

 ing at right angles to one another. These features suggest a 

 fluvial origin for the great series of strata lying west of the an- 

 dalusite mass. 



1 Published with the permission of the Director of the U. S. Geological Survey. 



