SUCCESSIVE DEPOSITS IN THE APPALACHIAN REGION 411 



of formation. As I have studied these formations for many years, ex- 

 amining practically all the important sections from the Helderbergs 

 southward to Georgia and westward to Michigan and Wisconsin, and as I 

 have further reviewed the literature on the subject and have studied a 

 large amount of material in the laboratory, and as, moreover, I have dis- 

 cussed the problems of these formations with my advanced students and 

 colleagues for years, I may, perhaps, be granted the right and ability to 

 offer interpretations worthy of consideration.* 



The Bald Eagle conglomerate. — In the region of its best development 

 today this formation is 1,319 feet thick, and consists of gray and brown 

 sandstones, with occasional pebble beds, resting directly on and grading 

 into the Upper Martinsburg (Hudson Eiver) shales, which are here about 

 700 feet thick. The upper part of the Martinsburg shale contains a few 

 massive calcareous beds, with poorly preserved fossils. Above this occur 

 some sandy layers, which become more pronounced upward and assume a 

 somewhat concretionary character. Finally, sandy beds predominate, 

 with only some shaly layers between them, and the rock gradually be- 

 comes a solid quartzite, with ripple-marked layers. A red bed appears 

 some distance up in the series, but red on the whole is scarce in the lower 

 beds. The presence of one such bed, however, indicates the beginning of 

 conditions permitting complete oxidation of the iron content of these 

 sands during deposition, a condition which later became very pronounced. 

 Crumplings and slickensided surfaces are common in the Bald Eagle, but 

 I do not think that much faulting has occurred. The present thickness 

 of ihQ series is essentially its original thickness. 



The age of the Martinsburg shale is certainly Utica, and it most prob- 

 ably also includes at least a part of the Eden. TJlrich, indeed, claims to 

 have fossils from the upper beds, which indicate that they belong to the 

 Maysville Ortliorhynchula zone. If the faunal evidence is no more con- 

 clusive than that on which he correlated the Upper Martinsburg shales 

 of the Mercersburg-Chambersburg area with the Eden (see beyond), it 

 may readily be discarded. I have collected from these upper beds and 

 carefully examined them, and T know thai fossils on the whole are 

 scarce, as well as poorly preserved, and 1 am convinced thai correlation 

 by the few found is a hazardous proceeding unless backed up by inde- 

 pendent stratigraphic evidence. Now, it is just this independent strati- 

 graphic evidence which is againsl such a correlation, as 1 shall proceed 

 to show. Moreover, Orthorhynchula linneyi, and presumably its asso- 



* I make these statements In protest of the habit, repeatedly Indulrod i-i i-i certal i 

 quarters, of objecting to my correlations because I was unfamiliar with tlu> sections 

 objections which generally ended by ilu> adoption of my correlations. 



