240 



C. L. HERRICK 



followed by a large series (over 200 feet) of alternating shales, quartz- 

 ites, and earthy or sandy limestones, the latter being quite fossilif- 

 erous. 



Of the Graphic-Kelly formation which in the Magdalena Mount- 

 ains, a few miles to the west, separates the Sandia series from the 

 granite, there is no trace. 



The Coal-Measure rocks soon become horizontal, and at the east- 

 ern side of the basin, where they abut upon the eastern boss or rib of 

 granite, they dip to the west and lie in juxtaposition to a fault exactly 

 similar to that on the western side of the first-mentioned or western 

 rib. In fact, the eastern rib is to all intents a repetition of the first. 



(ir-a.-nru1 e. 





s«t>i.<tt.a -Bet^s 



Fig. I 



and the Sandia series is repeated on the eastern aspect in all essential 

 respects as it occurs to the east of the western granite rib. 



Locally, however, there is a third fault which serves to repeat the 

 granite. This fault is a few hundred yards east of fault No. 2, and 

 in the interval there are preserved a few of the Sandia strata, though 

 in many places they are entirely removed by erosion. It is in the 

 V formed by these two faults that the best example occurs of the 

 fire-clay beds with the inclosed plant remains. In other localities 

 the fire clay also occurs beyond the influence of this local fault, but 

 these points are as yet little explored, and, in several localities visited, 

 the granite contact has only a silicious shale in the place of the fire 

 clay. 



The dip of the strata as they repose on the granite may be as high 

 as 70 degrees, but more often about 45 degrees. Passing eastward, 

 one crosses in succession a number of low hills, each capped by a bed 

 of quartzite, the intervals being filled with shale and limestone, the 

 superior resistance of the quartzites having thus impressed itself upon 



