582 E. O. ULRICH REVISION OF THE PALEOZOIC SYSTEMS 



Waverlyan and the Tennessean — also, that the Eopaleozoic is divided 

 into four systems instead of bnt two. 



Why the Waverlyan and Tennessean are systems and not series. — A 

 system is divided into series on similar grounds, only in these cases the 

 breaks are commonly of a lower order and the change in provincial boun- 

 daries less extensive. We may illustrate the difference by comparing the 

 relations of the Waverlyan to the Tennessean on the one hand and the 

 interrelations of the series divisions of these two systems on the other. 

 Thus, during the Waverlyan, the continental seas were developed in 

 southeastern North America in three fairly well distinguished basins or 

 faunal provinces. Each of these provinces, furthermore, is characterized 

 by its own lithological sequence. At times, also, the seas shifted so that 

 only two or perhaps but one of the basins was submerged. Named from 

 their characteristic formations, the eastern basin, with its shales and 

 sandstones, may be called the Cuyahoga basin; the middle area, with its 

 shales and cherty limestones, may be called the Fort Payne basin; the 

 western province, with shaly beds beneath and at the top and rather pure 

 crystalline limestone in the middle, may be called the Burlington province. 



It may be questioned whether all three of these basins contained marine 

 waters at any one time during this period. I believe this occurred during 

 the Chattanoogan and, to a considerable extent also, in the New Provi- 

 dence-Fern Glen-upper Cuyahoga age, and again in the Keokuk-Fort 

 Payne-Logan-Grand Falls age. The point is not of vital importance 

 here. It is enough to know that, as a rule, the Waverlyan seas occupied 

 considerable parts of at least two of the basins, and that the greatest 

 shifting during the period occurred at times marking the close of the 

 series into which the system is divided. Thus, as shown in the Maverlyan 

 correlation table, the Chattanoogan ends with its most widely distributed 

 stage; the Kinderhookian is characterized by frequent oscillations and 

 ends with its smallest (Chouteau) stage; the Osagian begins with the 

 extensive Fern Glen stage, continues with the restricted Burlington 

 stages, and ends with another eastward tilt, during which the Keokuk 

 was deposited in Towa and Illinois, the Grand Falls in Missouri and the 

 cherty Fort Pa3me limestone in areas to the southeast of these States. 



As indicated, the Waverlyan oscillations merely shifted the seas about 

 within the area covered by the three basins. The movements consisted 

 almost entirely of simple tilting of the area as a whole. The break 

 between the Keokuk and the Warsaw stage of the succeeding Tennessean 

 period, however, as described on page 588, is marked less by tilting than 

 by warping of the surface. The Warsaw, and to a greater extent the 



