NORTH MOSQUITO SECTION. 131 



but it seems probable tliat they are the remains of a sheet that once cov- 

 ered Loveland Hill in an analogous manner to the porphyry sheets on 

 Mounts Bross and Lincoln. 



By the erosion of the synclinal ravine above Park Citj' the White Lime- 

 stone is exposed in its bed with some irregular bodies of porphyry, and the 

 southern half of Loveland Hill, south of this ravine, ends to the eastward in 

 a cliff, at the base of which are exposed quartzites, apparently of the Cam- 

 brian formation, in which several ore bodies have been found. From the 

 base of this cliflF the formations sweep in a curve across Mosquito gulch 

 and up the north face of Pennsylvania Hill. The Cambrian and Silurian 

 outcrops can be traced in the bed of the gulch, dipping eastward at angles 

 of 20° to 25°, but the Blue Limestone outcrops are concealed by gravel 

 and alluvial deposits in the widening valley below. 



North Mosquito section. — The cHffs ou the south facc of Lovelaud Hill afford 

 a section of the lower Paleozoic, with their included intrusive sheets, simi- 

 lar to but even more perfect than that on its northern face toward Buckskin 

 gulch. Thin sheets of interbedded porphyry and porphyrite can be traced 

 along them for nearly two miles in practical continuity. The fault which 

 was observed on either side of Buckskin gulch is not found on this cliff 

 wall, but near the mouth of the canon is a more remarkable fault, whose 

 direction is at right angles to the one above mentioned. Seen from the other 

 side of the canon, the strata seem to slope rnpidly eastward until they abut 

 against the western side of a little knoll of granite, which projects out into the 

 valley at this point and deflects the stream to the southward. When one 

 actually climbs the cliff, however, it is found that there is a reduplication of 

 the lower part of the beds ; that a faulting has sheared or .split off a portion 

 of the strata on a southeast line, nearly parallel with the face of the cliff; 

 and that the piece thus separated has apparently fiillen down at its eastern 

 end to the base of the cliffs, while at its western end it still maintains its 

 connection with the regular line of outcrops. In Plate XIV is given a dia- 

 grammatic sketch of a portion of this cliff toward the eastern end, where the 

 steeper dips come in. In the foreground maj' be seen the faulted-down beds 

 referred to above, which form a low ridge or shoulder, standing out a little 

 distance from the face of the cliff. Above and back of this ridge the main 

 cliff I'ises nearly perpendicularly, showing the regular series of Cambrian 



