626 E. O. ULRICH- 



Page Plate 



Appalachian folding 410 



Protaxis 625, 626 



Appalachian Valley, Cause of trend of 565 



Deposits of Middle Cambrian in 621 



Diastrophic history during Cambrian of 620 



formations 27-29 



Map of Ordovician outcrops in . . 25 



Mountain, Births in 437 



Oscillation in southern . . . ' 412 



Seas with Atlantic connections in 571 



Sequence of Upper Cambrian in 622 



syncline 335 



tract, Bowing of 565 



troughs 414, 547, 562 



troughs, Migration of Ordovician seas in 544, 345 



troughs and overlaps (map) 293 



Apparent lithologic units often include stratigraphie hiatuses 526 



Arbuckle uplift 661 



limestone of 641. 661 



Fernvale outcrops of 305 



formations in . . 27. 29 



subdivisions of Arbuckle limestone 661 



Archeocyathus ? 639 



Arctic center of dispersal 487 



Faunal realm of 483 



Invasions of 488 



Map of , 368 



migrations, Paleozoic 48S 



Areal extent. Relation to rate of submergence to 540 



Arkansas formations . . 27, 28 



novaculite 477 



Arnheim fauna. Source of 339 



formation 586 28 



shale 422 



Asaphus 504 



Asaphus canalis 653 



cf . canalis 668 



n. sp.. near A. canalis ( Whitfield) 658 



Athens formation 414 27 



sandstone 549 



( shale 453. 538, 539, 55], 555 



shales fauna 550 



trough 371. 413. 414. 441. 453. 512. 538. 555. 556. 671 



trough, Formations in 27 



Atlantic and Pacific communication in Cambrian time 490 



Atlantic connections of Appalachian seas 571 



Removal of depositional evidence of 572 



