404 DESCRIPTIVE GEOLOGY. 



the west of this valley. The strike of the quartzite and limestone is approxi- 

 mately north 20° west, thus crossing the range diagonally, so that the lime- 

 stone body forms the summit of the ridge beyond the limits of the quartzite. 

 "With this direction continued southward, the limestone would strike 

 across the head of Box Elder Canon, where a characteristic Silurian coral, 

 Salysites catenulata, is said to have been found. The limestone, probably 

 of Silurian age, forms the west side of Copenhagen Valley, with a strike of 

 north 30° west. East of the valley, the range rises precipitously from 1,800 

 to 2,000 feet above the town, with short narrow canons to the westward, 

 and long gentle slopes toward Cache Valley. Brownish-yellow compact 

 quartzite forms the western slopes, overlaid near the summit by heavy dark 

 limestones which extend down to the base of the hills on the opposite side. 

 These formations undoubtedly belong to the Ogden Quartzite and the Wah- 

 satch limestone. The limestone is bluish-drab in color, usually fine-grained, 

 but carrying beds that are more or less granular and sometimes gritty. 



On the summit of the highest peak northwest of Copenhagen, in a dark 

 gray medium-grained bed of limestone, were found forms of Ptypora, 

 Aviculopeden, and Produdus, not, however, specifically determined. To 

 the southeast of the town, were found fragments of corals and species of 

 Zaphrentis, together with some Produdus, Spirifer, and Fenestella, all indic- 

 ative of the Lower Coal-Measure horizon. The road which leads from 

 Copenhagen to Wellsville in Cache Valley crosses the strata at a slight 

 angle, the upper bed striking north from 80°to 35° west, while the road has 

 a direction only a few degrees west of north, until, near the base of Box 

 Elder Peak, it turns abruptly westward, crossing the Wahsatch limestone 

 at nearly a right angle. There would seem to be here some dislocation in 

 the strata, which renders the structural relations somewhat obscure. 



Box Elder Peak is the culminating point of the range west of Cache 

 Valley. Its summit is formed of the upper beds of the Wahsatch lime- 

 stone, which dip to the northeast 45^ to 50°, with the slopes of the range, 

 and is more abruptly escarped to the west. In these limestones, the follow 

 ing forms have been recognized : 



Zaphrentis excentrica. 

 Zaphrentis Stanshuryl. 



