64 PROCEEDINGS OF THE WASHINGTON MEETING 



different from the usual methods in such work, the object being to take ad- 

 vantage of the unusual structural conditions. 



The Alabama marble is medium to fine grained, with distinctly interlocking 

 crystals. It is unusually translucent, sonorous, and resistant to abrasion and 

 weathering. These qualities, together with its warm coloring, explain its 

 growing popularity in the market. 



A careful study of the structural conditions in different parts of the field 

 show numerous examples of drag folding and, locally, schistosity in the marble. 



The sharp line of demarcation between calcite and dolomite beds is sug- 

 gestive of a distinct differentiation in the original sediments. 



Presented by title in the absence of the author. 



ORISKANY IRON ORE 

 BY E. J. HOLDEN 



(Abstract) 



This ore occurs in quantity only in Virginia. Its chief development has a 

 definite stratigraphic position at the top of the Lewistown limestone. The ore 

 bodies have thicknesses up to 40 feet and extend on the strike for distances 

 of a few hundred feet to half a mile and down the dip for several hundred 

 feet. Various theories of its origin have been given, but mining has shown 

 that the ore is secondary, and it now seems certain that the most productive 

 phase of the ore is a limestone replacement, the iron being derived from the 

 overlying shale. 



Presented in abstract extemporaneously. 



GEOLOGIC MAP OF THE FORT HALL INDIAN RESERVATION 

 BY GEORGE K. MANSFIELD 



(Abstract) 



The sedimentary rocks of the Fort Hall Indian Reservation include repre- 

 sentatives of all the great Paleozoic and later systems except the Cretaceous. 

 Igneous rocks, mainly extrusives, are present in great abundance and consider- 

 able variety, including a single occurrence of nepheline basalt. Some of the 

 Triassic and Jurassic rocks are so well developed as to require new sub- 

 division. The structure is quite complex, with both folding and faulting, 

 especially the latter, and there is an important thrust-fault, the Putnam over- 

 thrust. Three epochs of deformation and four of igneous activity have been 

 recognized. There may be others. Important deposits of phosphate occur in 

 the eastern part of the reservation. 



Presented by title. 



