THE DEVONIAN SECTION NEAR ALTOONA, 

 PENNSYLVANIA^ 



CHARLES BUTTS 

 United States Geological Survey, Washington, D, C. 



STRATIGRAPHY 



Introduction. — This joint article has grown out of work done in 

 connection with the geologic survey of the Ebensburg quadrangle, 

 which is about 5 miles west of Altoona. Fig. i shows the location 

 of the section of the state, and Fig. 2 shows in greater detail the 

 area studied and the location of the profile section, Fig, 2. The rocks 

 of the greater part of the Devonian section of the region are very 

 well exposed along the Pennsylvania Railroad west of Altoona, and 

 along the New Portage branch of the same west of Hollidaysburg. 

 They strike about N. 40° E., and dip regularly to the northwest 

 with a uniformly diminishing degree. Only one fault of any con- 

 sequence is known. It is shown in the profile section, Fig. 2. The 

 downthrow is apparently 100 feet to the east. 



In previous surveys of this region it was recognized that the mass 

 of shale and thin sandstones between the Oriskany sandstone below 

 and the bottom of the Catskill above represents the Marcellus, 

 Hamilton, Genesee, Nunda (Portage), and Chemung formations; 

 yet, on account of the generally homogeneous character of the mass 

 as a whole, no effort was made to discriminate and map the indi- 

 vidual formations. It has been found possible, however, by taking 

 careful note of the lithologic and paleontologic characters of the rocks, 

 to identify the main formations recognized in New York state, and to 

 establish and map the limits of the same with a fair degree of pre- 

 cision, as will appear in the following description. The section 

 described in this paper then consists of the Oriskany sandstone, 

 the Marcellus shale, the Hamilton formation, the Genesee shale, 

 and the Nunda, Chemung, and Catskill formations. With the 

 exception of the Marcellus, which is not certainly known at Altoona, 

 :jhe above mentioned formations are shown in the profile section, 

 Fig. 2. The section begins at the intersection of Seventeenth Street 



I Published by Permission of the Director U. S. Geological Survey. 



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