136 THE DEVONIAN AND CARBONIFEROUS. [bull. 80. 



He proposed u the use of the name" " Mississippi limestone series or 

 Mississippi group" "as a geographical designation for the Carbonifer- 

 ous limestones of the United States which are so largely developed in 

 the valley of the Mississippi Kiver." 



At the time this was written the Chouteau group of Broadhead was 

 correlated with the Chemung group of the New York geologists, and one 

 of the important results of WinchelPs paper was the demonstration 

 that the Chouteau group of Missouri, the Kinderhook group of Illinois, 

 the Waverly group of Ohio, and the Marshall group of Michigan were 

 different types of a single formation of more recent age than the Che- 

 mung group of New York. 



As the Carboniferous age of the Chouteau and Kinderhook faunas is 

 fully established, it appears entirely appropriate to extend the limits of 

 the Mississippian series so as to include all the formations containing 

 Carboniferous faunas from the top of the Devonian to the base of the 

 Coal Measuses. I have already proposed the use of the name in this 

 sense in recent reports to the State geologists of Arkansas and Missouri. 



As the nature of sedimentation fe greatly determined by the geo- 

 graphical relations of ocean to shore lines, a brief description of the 

 geographical conditions of the region during the upper Paleozoic is 

 here appended. 



At the opening of the Devonian period the Archean continental 

 nucleus of the Northeast had been increased by a considerable border 

 of Silurian formations. The borders of this land mass roughly defined 

 extended from near the mouth of the Mackenzie Eiver southeastward 

 to Lake Winnipeg, and as the line approached Lake Superior it was 

 diverted westward, to what extent we do not know, as the more recent 

 deposits cover the record. The shore line appears again running across 

 the northeast corner of Iowa, thence eastward across Illinois, and there 

 suddenly bends northward, forming a great bay, taking in the peninsu- 

 lar part of Michigan ; thence eastward across Ontario, northern New 

 York, and around the Catskill Mountains into New Jersey ; thence with 

 some interruptions south westward, forming an eastern shore for the 

 Appalachian basin. 



The Cincinnati uplift was probably an island for part of the Devon- 

 ian period, and the Ozark uplift of southeastern Missouri formed an- 

 other large island, which probably remained above water throughout 

 the Carboniferous. Other islands may have furnished shores of erosion 

 farther to the south and west. Thus from the beginning of the Devon- 

 ian till the time of the general continental elevation which initiated the 

 Coal Measures, the central part of the United States was a vast ocean 

 basin. The sedimentation about the margins of this basin was prevail- 

 ingly arenaceous and argillaceous, the formations are more varied, and 

 it is in these margins that we find the best development of the Devon- 

 ian system, both stratigraphically and faunally considered. As we 

 approach the central portion of the basin the sedimentation is prevail- 



