736 



JOHN W. GRUNER 





which arched up the overlying formations and metamorphosed 

 the sediments. 



One of the largest exposures of this batholith is along the Rio 

 Hondo, where a Hght-gray, very coarse biotite granite outcrops. 

 It weathers easily and forms curiously shaped pinnacles in some 

 places. Also along Lucero Creek a pinkish, more or less gneissoid, 

 granite is found. The latter is also the predominating rock in the 



Salazar Canyon, and from here a 

 broad belt of it passes beneath Lucero 

 Peak to Old Mike. 



The rocks from Old Mike and Red 

 Dome show every gradation from a 

 typical red granitic gneiss to a 

 medium-grained biotite granite. 

 Medium-grained biotite granite vary- 

 ing in color from pink to greenish 

 gray also covers a large part of Red 

 River Canyon, especially on the west 

 side. A detailed examination was 

 impossible in this part of the district. 

 Half a mile west of Larkspur Point 

 pink medium to coarse-grained granite 

 outcrops on the steep slope above 

 Indian Creek. South of Larkspur 

 Point the continuation of this outcrop 

 is found in contact with remnants of 

 ancient schist that caps a part of 

 Larkspur Point. Farther toward the southeast the gneissoid granite 

 is exposed along the northwestern tributary of Pueblo Creek for a 

 distance of two and a half to three miles. 



Basic dikes. — A number of basic dikes are intrusive into the 

 granite of the bathoUth. Their age is probably pre-Cambrian. 

 The most prominent one occurs just east of the highest point of 

 Pueblo Peak and has a width of loo to 150 feet. Its trend cor- 

 responds to that of the others, which have a northwest to southeast 

 direction. In composition and texture it approaches a gabbro. 



Fig. 3. — Pueblo quartzite on 

 Ben Hur Lake. Looking north- 

 east. Unconformity on upper left. 

 Pennsylvanian beds nearly at right 

 angles to sheeting of quartzite. 



