556 A. W. GRABAU LOWER ORDOVICIC FORMATIONS 



Page 



General discussion 611 



East Scania 612 



West Scania 614 



Tosterup 617 



Ordovicic of Bornholm 618 



Summary of the early Ordovicic sections 619 



Introduction 



Geologists familiar with the formations of both hemispheres will in 

 general agree that while Europe must always serve as the type region for 

 the Mesozoic and Cenozoic formations, the North American Paleozoic 

 should be considered the standard by which other deposits of that age 

 must be judged. In no other known region is there such an extensive 

 development of the older formations, both in their marine and continental 

 phases, and in no other known portion of the world is the record so clearly 

 preserved as in the Paleozoic rocks of the greater part of the North 

 American continent. This is especially true of the earlier systems, which 

 have not only a slight representation over much of Europe, but are for 

 the most part strongly disturbed; or, where not so affected, as in the 

 Eussian region, are in large part covered by comparatively recent surface 

 deposits. This is emphasized by the extent of the treatment accorded 

 the several divisions of the column in the standard European treatises. 

 Thus, Kayser in his "Lehrbuch der Geologischen Formationskunde," 

 fourth edition, devotes 273 pages to the Paleozoic and 400 pages to the 

 remainder of the column, above the Paleozoic, the Paleozoic thus receiv- 

 ing about 40 per cent of the whole. Of the 273 pages given to the Paleo- 

 zoic, 30 are devoted to the Cambric, 55 to the Ordovicic and Siluric, 60 

 to the Devonic, 66 to the Carbonic (including the Mississippic), and 61 

 to the Permic. Of the 217 pages devoted to the Mesozoic, 81 go to the 

 Triassic, 60 to the Jurassic, and 76 to the Cretacic, including the Co- 

 manchic of American usage. Haug in his "Traite de Geologic" gives 

 34 pages to the Cambric, 50 to the Ordovicic and Siluric, 71 to the 

 Devonic, 105 to the Anthracolithic (Mississippic-Permic), or a total of 

 260 pages to the Paleozoic. To the Triassic he gives 81, to the Jurassic 

 224, and to the Cretacic (inclusive of Comanchic) 244, making a total 

 of 549 to the Mesozoic, or more than double that given to the Paleozoic. 

 The Tertiary (Cenozoic) is discussed in 363 pages and the Quaternary 

 (Psychozoic). in 162 pages. The Paleozoic thus receives 19.5 per cent, 

 or about one-fifth of the space devoted to the entire post-Algonkic history 

 of the earth. 



