478 C. D. Walcott — Cambrian Hocks of Pennsylvania. 



the central mass of the range, which is now a mountain 

 valley between the Cotoctin and Blue Ridge ridges. The 

 schist extends to a point one-fourth to one-half a mile beyond 

 the Blue Ridge station, on the Western Maryland R. R. 

 Fragments of a rhyolite-like, porphyritic rock* were also seen, 

 that probably represent the " bedded petrosilex " of Dr. Hunt, 

 as shown two miles south of this Monterey road, near Fox- 

 ville, Maryland. Going down the road beyond Pen Mar 

 towards Pikesville, there was an apparent repetition of the 

 section on the eastern side of the ridge, near Mechanicstown. 

 Subsequently, an examination was made of the section from 

 Monterey, Franklin county, Pennsylvania, to the valley on the 

 line of the Waynesborough turnpike. Just west of Monterey 

 a massive quartzite forms a plateau, upon which the Monterey 

 hotel is situated. The dip of the quartzite is slightly to the 

 northwest. A short distance beyond the toll-gate the dip to 

 the northwest increases, and a series of sandy and argillaceous 

 shales succeeds the quartzite. Following down the turnpike 

 toward Waynesborough and near the foot of the ridge, these 

 shales were found to pass beneath a light-colored, hard, com- 

 pact quartzite dipping northwest, in which numerous remains 

 of Scolithus linearis occur. By breaking the white quartzite 

 many fragments of Olenellus showing parts of the head and 

 thoracic segments were also found. In calcareo-arenaceous 

 layers, just beneath the quartzite, fragments of Olenellus 

 occur associated with specimens of Camerella minor. A series 

 of more or less sandy shales next appears resting upon the 

 Scolithus quartzite and having a northwesterly dip, toward 

 the valley. Along the foot of the ridge, low hills of sandy 

 shale and slate appear, capped with a thin-bedded calcareous 

 quartzite or sandstone. In the latter, Camerella minor, 

 Hyoliihes communis, and fragments of Olenellus are abundant. 

 A little west of these hills the limestones of the valley appear. 

 In this limestone, Kutorgina n. sp., and fragments of the head 

 and thoracic segments of Olenellus were found a little east of 

 the road leading up the east branch of Little Antietam creek 

 and about three miles east of Waynesborough. 



If reference is now made to the York county section it will 

 be seen that the upper portion of the Monterey section is 

 essentially a repetition of it — from the Scolithus quartzite to 

 the limestones of the valley. The same fossiliferous Scolithus 

 quartzite passes beneath sandy shales and slates, in which are 

 interbedded calcareous quartzites carrying the Olenellus fauna ; 

 these pass beneath the limestones of the valley in York 

 county in which the Olenellus fauna occurs. In the Monterey 



* The description of the volcanic rocks of South Mountain by Dr. G. H. 

 Williams is contained in the following article, p. 482. 



