PACKER BASIN. 151 



for long distances from one mountain to anotlier. In this way it becomes 

 an easy matter to correlate strata in such blocks as Islan<l and Leader 

 mountains and Sugar Loaf The deep gorges jjcnetrating the limestones 

 ati'ord grand exposures. Sugar Loaf offers one of the 1)est points of view 

 for gaining a clear understjuiding of the synclinal structure of tlie Silverado 

 Hills, the characteristic belts of sandstones and mottled limestones being 

 readily traceable from an easterly to a westerly dip. The summit of Sugar 

 Loaf is formed of Ui)[)er Devonian strata, with abrupt escarpments on all 

 sides. At the east base of this isolated mountain, the Rescue Canyon fault 

 may be traced crossing the ridge betw^een the head of Rescue Canyon and 

 the faulted block of White Pine shales at Charcoal Cannon. From Sugar 

 Loaf northward to Packer Basin all the limestones on the west side of the 

 fault dip westerly, the fault following the line of contact between the 

 Nevada limestone and the White Pine shale. ( )i)portuuities for observing 

 these westerlydipping beds maybe found in Charcoal and Ox Bo^v canyons, 

 the streams which cut the ravines crossing the strata nearly at right angles 

 to their strike. 



Packer Basin.— Packer Basiu is a small depressed block of Nevada lime- 

 stone lying between the northern end of the main ridge and the broad 

 basalt table, the abrupt wall of the latter shutting in the basin on the north. 

 As the basin lies on the ver}- edge of a broad volcanic field, it has naturally 

 undergone a good deal of dislocation, and is much broken up by pumices 

 and tuffs, wdiich partly fill the basin, having poured out along a fissm-e 

 on the w^est side of the faulted block. It is interesting to see here the same 

 association of pumices and tuffs, followed by a later outburst of basalt, in 

 all respects similar to those occurrences seen in so many other places 

 bordering the uplifted block. The limestone still maintains the north and 

 south strike and westerly dip of the main ridge to which it really belongs. 

 Its chief interest lies in the finding in a massive blue limestone a fauna 

 characteristic of a somewhat higher horizon than those observed at Wood- 

 peckers and Basalt peaks. Additional interest is derived from the disappear- 

 ance of the Rescue fault and the accompanying White Pine shales beneath 

 the basalts. 



