Butts — Geologic Section of Pennsylvania. 523 



Art. XXL — Geologic Section of Blair and Huntingdon 

 Counties, Central Pennsylvania;* by Charles Butts. 



The geologic section in Blair and Huntingdon counties, 

 Pa., was worked out by the writer in 1908 in a survey of 

 the Hollidaysburg quadrangle and in 1913 in a survey of 

 the Huntingdon quadrangle, which adjoins the Hollidays- 

 burg quadrangle on the east. These two quadrangles 

 include a large part of the two counties and lie across two 

 great folds, the Nittany anticline and Broad Top Moun- 

 tain syncline. The strata exposed have a maximum 

 thickness of over 27,000 feet and an average thickness, as 

 shown in the accompanying section, of nearly 25,000 feet. 

 This is probably as thick as any if not the thickest section 

 exposed in the Appalachian region in so small an area. 



Geologists familiar with the region will see that the 

 writer's contributions to the stratigraphy consist partly 

 of detail, such as the delimitation of the Middle and 

 Upper Devonian formations recognized by the geologists 

 of the Second Geological Survey of Pennsylvania but the 

 boundaries of which were not denned by them. Much 

 that is new has, however, been added, particularly con- 

 cerning the lower part of the section, where the valley 

 limestone, No. 2 of the older geologists, has been split up 

 into twelve formations and several members. 



Brief notes, mainly on the new formations and their 

 names, follow. In the Chemung the name Saxton con- 

 glomerate member is introduced to replace White 's name 

 Lackawaxen conglomerate, as it seems very uncertain 

 whether this conglomerate is the same as the Lacka- 

 waxen. The conglomerate is well exhibited in and about 

 Saxton, Huntingdon County, whence the name. 



The Portage group has been divided into two forma- 

 tions, the Brallier shale and the Harrell shale which 

 includes, in the bottom, the Burket black shale member. 

 The Brallier shale is named from a station on the Hunt- 

 ingdon & Broad Top Mountain Railroad a few miles 

 northeast of Everett, in Bedford County. This shale is 

 the same as the Woodmont shale member of the Jen- 



* Published by permission of the Director of the United States Geological 

 Survey, with the statement that parts of the classification and nomenclature 

 have not yet been officially adopted. All the names of formations and 

 members shown in the stratigraphie column have, however, been adopted 

 by the Survey. 



