CHAPTER XII. 

 CONCLUSIONS. 



When this essay was begun it was thought possible to prepare a 

 thorough paleontologic definition of the systems and series under con- 

 sideration. The result has demonstrated that the facts are not yet 

 accumulated to make this possible. In the first place, the formations 

 themselves are not delimited on the same basis in different provinces, 

 and, secondly, the fossils have been reported under so many different 

 names that a thorough revision of the several biologic groups is neces- 

 sary before the various lists prepared can be scientifically correlated. 

 In the meantime such lists as Mr. Miller's "American Paleozoic Fossils" 

 will suffice for all practical purposes. At the outset it was thought 

 that an exhaustive review of all American literature on the Devonian 

 and Carboniferous systems would be profitable. As the research has 

 progressed it has become evident that this literature may be divided 

 into three classes, viz: (1) Records of observations and facts ; (2) dis- 

 cussions of the relations and classifications of the facts ; (3) controver- 

 sial literature. Although all the accessible literature has been con- 

 sulted, I have concluded that the first class can not be abstracted to 

 advantage ; that the third class has generally been more concerned in 

 the defense of personal opinions than in the elaboration of the truth, 

 and in many cases the controversy has been occasioned by imperfect 

 understanding of the views of others. For the present essay selection 

 has been made chiefly from the second class of literature, written in 

 most cases by those exhibiting some acquaintance with the immediate 

 local problem under discussion, and also with the opinions of others, 

 and with the corresponding formations in other regions. Another re- 

 striction was found necessary: To go into full details would have made 

 a book so large that few would take the trouble to read it, hence when- 

 ever practicable formulations of results have been given, leaving the 

 student to examine the original works for details. For these various 

 reasons a large number of the authors consulted, probably a large ma- 

 jority, are not represented here by quotations or title. 



The territory discussed may be classified for our purposes into the 

 following geographic provinces: Acadian, Appalachian, Mississippian, 

 Michigan, Western, and Northern provinces. The Acadian province is 

 geologically isolated from the others, and has a history of its own. The 

 facts accumulated for the Northern province, extending from Manitoba 

 258 



