Huntingdon Counties, Central Pennsylvania. 527 



new, although the presence of the Ozarkian in this region 

 was recognized by Ulrich in 1909 or 1910. 



The Larke dolomite is named from Larke postoffice, 

 which is several miles south of Williamsburg, in Blair 

 County, where thick beds of the dolomite are exposed. 

 A good specimen of Helicotoma uniangulata was found 

 in the Larke near Ore Hill, farther west in the county, 

 and shows that it contains beds, perhaps in its upper 

 part, of the age of Ulrich 's Chepultepec dolomite of Ala- 

 bama, of the Gasconade limestone of Missouri, and of the 

 upper cherty, fossiliferous zone of the Little Falls dolo- 

 mite of the Mohawk valley of New York. Good expos- 

 ures of the Larke occur just east of Williamsburg. 



The Mines dolomite is named from the old mining town 

 of Mines, which is several miles southwest of Williams- 

 burg, where brown iron ore was once extensively mined 

 by the Cambria Steel Co. This formation seems to occupy 

 the position of the Copper Ridge dolomite of Ulrich, 

 which in Tennessee is the main body of the Knox dolo- 

 mite, lying between the Canadian (Beekmantown) part of 

 the Knox and the Nolichucky shale. The Mines dolomite 

 is best exhibited in the north end of the long ridge just 

 southeast of Williamsburg, Pa. 



The Gatesburg formation is named from Gatesburg 

 Ridge, in Center County, Pa., the name having been pro- 

 posed by Prof. E. S. Moore, of State College. 



The Ore Hill and Stacy members were named by the 

 writer. The Ore Hill is named from a mining town south 

 of Roaring Spring, Blair County. This member has 

 yielded several species of trilobites, mostly undescribed 

 forms, the nearest relatives of which, according to Ulrich, 

 occur in the Hoyt limestone of New York. The Ore Hill 

 is well exposed in a quarry a mile southwest of Ore Hill 

 and at a point just north of the road a half mile north- 

 west of Drab in the Huntingdon quadrangle, 6y 2 miles 

 southwest of Williamsburg. Most of the fossils were 

 collected at these localities. The Stacy member is named 

 for Stacy Hill, an isolated knob 4 miles slightly west of 

 south of Williamsburg. 



The Gatesburg is nowhere well exposed but can best be 

 seen on the north bluff of the river, a mile northeast of 

 Williamsburg and along the north bluff a short distance 

 west of Williamsburg. It is also well exposed along the 



