THE BASIN PROVINCE 143 



(Page 35.) "In the central and southeastern portions of the Florida Moun- 

 tains and the central portion of the Victorio Mountains and extending part 

 way around the north end of the Tres Hermanas Mountains there is a thick series 

 of limestones to which it is proposed to apply the name Gym limestone. * * *" 



This limestone appears on the top of peaks and fault blocks in scattered 

 areas through the county. It is the uppermost formation of the Paleozoic. 



(Page 36.) "The formation consists chiefly of limestone, in greater part 

 massively bedded, of light-gray color, and showing a brecciated structure in many 

 beds. In Gym Peak and vicinity the lower member is dark and the one next 

 above it is much lighter in color, with an abrupt change from one to the other, 

 and the thickness remaining in this area and west of the peak is at least 700 feet. 

 In the canyon i mile southeast of Gym Peak limestone apparently in the middle 

 of the formation dips steeply southeastward under 80 feet of dark-gray fissile 

 shale which is traceable for about half a mile and again appears along the great 

 fault on the trail a short distance west of Gym Peak. This black shale is overlain 

 on the east by cherty limestone containing abundant Manzano fossils, and this 

 limestone is finally cut off by the great fault which crosses the mountain. * * *" 



In one locality in the Tres Hermanas Mountains the Gym limestone 

 passes under "gray quartzite, which is the highest member exposed." 



The fossils studied by Girty indicate that the relation is with the 

 Manzano, but some of the gastropods indicate the Hueco. Later Darton^ 

 said of the Manzano group : 



(Page 53.) "The Manzano group is represented in central and northern 

 New Mexico by the Gym limestone, which crops out extensively in the Florida 

 Mountains, type locality, and also in the Victorio Mountains. * * * The Gym 

 limestone also appears extensively in the Tres Hermanas Mountains, where it is 

 uplifted and cut by porphyry, and it also crops out in a few small hills rising out 

 of the desert in the south-central part of the county. The formation has not 

 been recognized outside of Luna County, although doutbless it is represented in 

 the Manzano and Hueco sections in other areas. * * *" 



"The formation consists almost entirely of light-gray limestone, mostly 

 massive and in part brecciated. An 80-foot member of dark-gray shale is 

 apparently included on the southeast slope of the Florida Mountains, but this 

 may be the Percha shale overlapped, or faulted into its present position. In the 

 Tres Hermanas Mountains part of the Gym limestone is metamorphosed to 

 white marble and there is included a member of 50 to 60 feet of gray to reddish 

 quartzite. * * *" 



"In the San Andreas and Sacramento mountains and farther north in New 

 Mexico the stipposed equivalent of the Gym limestone is separated from the 

 Magdalena group by a thick series of red beds (Abo sandstone), but these beds 

 are lacking in the southwest corner of the State and also in the region near and 

 east of El Paso. 



(Page 55.) "* * * Pennsylvanian and Permian time is represented in the 

 main by deposits of the Magdalena and Manzano groups and the Hueco and Gym 

 limestones. The Hueco and Gym are contemporaneous, at least in part, with 



^ Darton, N. H., A Comparison of the Paleozoic Sections in Southern New Mexico, U. S. 

 Geological Survey, Professional Paper No. 108-C, 1917. 



