CHAPTER III. 



PALEOZOIC ROCKS AND ERA. 



SECTION I. GENERAL DESCRIPTION. 



The Lost Interval. Between the Archaean and Pale- 

 ozoic rocks occurs the greatest and most universal break 

 in the whole stratified series. At this point in time 

 occurred the greatest and most wide-spread changes in 

 physical geography and climate which has ever occurred 

 in the history of the earth. The justification for this 

 statement is found in the fact that everywhere, even in 

 the most distant localities, we find the lowermost Paleo- 

 zoic (Primordial) lying unconformably on the Archaean. 

 No one has yet seen the two series continuous. Now, 

 when we remember that unconformity always means a 

 previous eroded land-surface (page 192), and stratified 

 rock a sea-bottom, we easily perceive how wide-spread the 

 changes of physical geography must have been at this 

 time. Again, when we remember that unconformity also 

 always means a lost interval unrecorded at the place ob- 

 served, and that the unconformity exists at all observed 

 places, we at once see that right here is an unrecovered, 

 probably an irrecoverable, lost interval of time. During 

 the lost interval wide areas of land existed, which were 

 afterward submerged and covered with Paleozoic sedi- 

 ments. As compared with the early Paleozoic, it was 

 evidently a continental period. 



Corresponding with the great physical changes here, 

 there was also immense advance in life-forms. During 



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