abstracts: geology 133 



Tonopah Junction, Nevada, and Laws, California. The line is 547 

 miles long and fixes the elevations of 228 permanent bench marks. 

 The elevation of the top of rail in front of the railroad stations along 

 the line was also determined. The elevations of the bench marks and 

 of the top of rail in front of the railway stations are given in meters 

 and also in feet. As in all precise leveling in the United States the 

 datum used is mean sea level. The highest point of the line is at 

 Sunland, Nevada, 2171 meters (7122 feet). 



The result of a study of the errors of leveling is also given in this 

 publication. The practice of the observer, while setting up the instru- 

 ment, always to face in the same direction with respect to the line of 

 progress had a tendency to make the line of sight higher for the back 

 sights than for the fore sights. The effect of this has been eliminated 

 by the observer facing in opposite directions at alternate set-ups of 

 the instrument. H. G. A. 



GEOLOGY. — Geology of the Hound Creek district of the Great Falls 



coal field, Cascade County, Montana. V. H. Barnett. U. S. 



Geological Survey Bulletin 641-H. Pp. 215-231, with 1 plate. 



1916. 



This paper describes the geologic formations, the structure relating to 



the occurrence or absence of coal-bearing rocks, and the coal resources 



of the Hound Creek district. The rocks that crop out in the district 



belong to the Carboniferous, Jurassic, and Cretaceous systems, but 



detailed study was confined to the coal-bearing Kootenai formation 



(Lower Cretaceous). R. W. S. 



GEOLOGY. — Contributions to the geology and paleontology of San Juan 

 County, New Mexico. I. Stratigraphy of a part of the Chaco River 

 V alley. Clyde Max Bauer. U. S. Geological Survey Pro- 

 fessional Paper 98-P. Pp. 271-278, with 8 plates. 1916. 

 This paper is an attempt to set forth the principal features of the 

 stratigraphy in a part of the San Juan Basin, to describe the succession 

 of strata irrespective of possible correlations and thereby to establish a 

 type section for the formations exposed, and to bring out their relations 

 to the strata immediately above and below. 



The area studied and mapped comprises about 1500 square miles in 

 northwestern New Mexico extending along Chaco River for about 50 

 miles from the Great Hogback to Meyers Creek. It includes the out- 

 crops of strata overlying the Mesaverde formation, which have in the 



