SUCCESSIVE DEPOSITS IN THE APPALACHIAN REGION 421 



correlation of the upper beds with Eden is unsupported by fossils and by 

 other stratigraphic evidence, to be noted presently, while my correlation 

 of these beds with Upper Lorraine is not only supported by fossils, but is 

 rendered next to imperative by the relationships of the strata. 



The post-Trenton rocks of the region between Utica and Watertown 

 comprise at the base the Utica shale, about 600 feet thick, the Frankfort 

 shale, and the Pulaski shale, the two together constituting the Lorraine 

 group. Above these comes the white Oswego sandstone, which has a 

 thickness on the Salmon River of about 110 feet, and at Oswego is suc- 

 ceeded by the red beds. There is no break in the series of strata from 

 the Trenton to the Oswego, each grading into the other. Ulrich, to be 

 sure, separates the Trenton and Utica of this region (north central New 

 York) by a break, but this is an absolutely unwarranted proceeding and 

 evidently done to fit a theoretical scheme of correlation, which has no 

 sound basis in fact. 



Observation after observation shows that the Trenton and Utica are 

 formations representing continuous deposition. The evidence is abso- 

 lutely conclusive that the Trenton type of sedimentation is gradually re- 

 placed by the Utica type. Indeed, the Utica type of mud began while 

 Trenton conditions were still dominant — that is, while in the main the, 

 organic limestones were accumulating, the black muds repeatedly in- 

 vaded the region of such deposition, this resulting in the formation of 

 intercalated layers of black shale between the limestone beds. The shales 

 commonly contain the Utica graptolites and the limestone the Trenton 

 fauna. As I have repeatedly stated, the black mud phase which consti- 

 tutes the Utica shale of Utica and of the region to the northwest is 

 merely an eastern mud phase of the Trenton type of deposition, which 

 was organic limestone. Eastward the mud deposition began earlier; the 

 black shales are thicker and the limestone thinner. The black muds have, 

 of course, their distinctive fauna, chiefly graptolites and such trilobites as 

 Triarthrus beclci. This latter is cited by Ulrich from the basal 10 feet 

 of the Martinsburg shales. I have elsewhere stated that I regarded the 

 Lower Martinsburg shale of eastern Pennsylvania as the mud equivalent 

 of the Trenton limestone of Pennsylvania, and 1 may reiterate here that 

 T consider the lower S00 or 1,000 \'wl of the Martinsburg, which litho- 

 Logieally has the character of the Utica, the real Utica in the wider sense 

 of the term, namely, that it is the black mud focies which in central 

 Pennsylvania (Center County, etcetera) is represented by Trenton lime- 

 stone and thin shale. In the same way I consider the Lower I'tica shale 

 and intercalated sandstones of the eastern part of the Mohawk Valley, 



