COMPARISON BETWEEN EUROPE AND NORTH AMERICA 557 



In the large volume on the Paleozoic of the world, in the Lethsea 

 Geognostica, Freeh devotes 45 pages to the Cambric, 56 to the Ordovieic- 

 Siluric, 140 to the Devonic, and 408 pages to the remainder of the Paleo- 

 zoic. The Triassic is treated in a separate volume of 561 pages, while 

 the higher formations promise to be treated with similar generosity. 



If we now look at the volumes of Chamberlin and Salisbury, where the 

 American standpoint is taken, we find that the Paleozoic has devoted to 

 it 460 pages, of which 86 go to the Cambric, 64 to the Ordovicic, 50 to 

 the Siluric, 78 to the Devonic, 43 to the Mississippic, 80 to the Pennsyl- 

 vania, and 59 to the Permic. The Triassic is considered in 58 pages, 

 the Jurassic in 47 pages, the Comanchic in 31 pages, and the Cretacic 

 proper in 54 pages, making a total of 190 for the Mesozoic. The Tertiary 

 receives 136 pages and the Quaternary 216 pages; thus the Paleozoic 

 comprises nearly 46 per cent of the entire treatise on post-Algonkic 

 systems. 



In the fourth edition of Dana's "Manual" 278 pages are devoted to the 

 Paleozoic, 141 to the Mesozoic, and 158 to the Tertiary and Quaternary, 

 the Paleozoic receiving thus 49 per cent, or nearly one-half, of the space 

 given to the entire post-Archean portion of the section on Historical 

 Geology. If the various treatises were strictly devoted each to its own 

 country, the discrepancies would be even more marked than they are. 



In the succeeding pages of this paper some of the Lower Paleozoic for- 

 mations of Europe are considered in the light of the knowledge gained 

 by a study of American formations of the same age. My field studies in 

 Europe were made during the last eight months of the year 1910, and 

 the material then collected has been studied at intervals since that time 

 in the laboratory. While considering the lithologic and faunal characters 

 of the several formations, emphasis will also be laid on the evidences for 

 the occurrences in the European field of the disconformities and hiatuses 

 known to separate certain American formations, and which may owe their 

 existence to diastrophic movements. 



Lower Ordovicic of Europe and North America compared 



The classification of the Ordovicic rocks of western Europe is generally 

 based on the British succession, since that was the first to be determined 

 and defined. As is well known, these rocks were called by Sedgwick 

 Upper Cambrian, and by Murchison, Lyell, Phillips, and others, Lower 

 Silurian. Even the Lingula flags and the Menevian were included bv 

 Jukes (1863) in the Lower Silurian or Cambro-Silurian. while Murchison 

 (1868) called them "Primordial Silurian." The Geological Survey in 



