286 E. O. ULRICH REVISION OF THE PALEOZOIC SYSTEMS 



Page 



General discussion of principles 532 



Summary of diastrophic criteria 534 



Categorical review of principles of correlation by diastrophic move- 

 ments 535 



General statement 535 



Principles based on manifest stratigraphic relations 536 



(1-8) Correlation by unconformities, overlaps, and determi- 

 nable values of hiatuses 536 



Principles based partly or wholly on inference 540 



(9) Relation of areal extent and thickness of formations to 



rate of submergence 540 



(10) Correlation by evidence of sea-filling and tidal flats. ... 540 



(11) Correlation by evidence of progressive submergence. ... 541 



(12) Change in character of sediments indicative of dias- 



trophic movement 541 



(13) Differential effect on strandline in continental tilting.. 542 



(14) Correlation implying local tilting and warping 542 



(15) Correlation by probabilities depending on rhythm of 



ments 543 



(16) Correlations implying complete emergence of continents 



at frequent intervals 545 



The Ozarkian illustration 548 



Complete emergence at close of Pamelia Stones River. . 5.50 



The Ozarkian-Canadian emergence 551 



The Canadian-Ordovician emergence 553 



(17) The principle of maximum thickness of overlapping 



formations 5.54 



Demonstration of the principle by the Lowville overlap. 5.54 

 Demonstration by alternating northward and south- 

 ward overlaps in the Mississippi Valley 557 



Demonstration by Niagaran overlaps 558 



(18) Correlation based on inferred rhythmic shifting of the 



area of maximum deposition in successive ages 501 



Subdivision of the Appalachian and Allegheny geosyn- 



clynes by transverse axes 562 



Barrier efficiency of the Harrisburg axis 563 



Formations limited by the Staunton barrier 564 



The Wytheville axis as a barrier 564 



The Gadsden barrier 564 



Bowing of the Appalachian tract .565 



Application of the principle 566 



Shifting of Ordovician seas 566 



Sea-shifting largely due to localized surface warping and 



torsion , 568 



(19) Atlantic invasions occasionally superseded without 



break by Gulf of Mexico invasions 569 



(20) Regarding oceanic connections of continental seas 571 



Appalachian seas with Atlantic connections 571 



Depositional evidence of postulated Atlantic connections 



now almost entirely removed 572 



