CONTENTS xiii 



CHAPTER XX 



THE MISSISSIPPIAN (EARLY CARBONIFEROUS) PERIOD 

 FORMATIONS AND PHYSICAL HISTORY 596 



East of the Great Plains, 597. In the Great Plains, 600. West of 

 the Great Plains, 600. General considerations, 601. Lower 

 Carboniferous of other continents, 603. Climate and duration, 

 606. 

 THE LIFE OF THE MISSISSIPPIAN (SUBCARBONIFEROUS) 606 



Marine faunas, 606. Kinderhook fauna, 607. Osage fauna, 607. 

 Waverly fauna, 611. Great Basin fauna, 611. Genevieve (St. 

 Louis-Kaskaskia) fauna, 613. Evolution of the fishes in the 

 Mississippian period, 617. Land life of the Mississippian, 619. 



CHAPTER XXI 



THE PENNSYLVANIAN (UPPER CARBONIFEROUS) PERIOD 



FORMATIONS AND PHYSICAL HISTORY 620 



Pottsville conglomerate (Millstone grit), 620. Coal measures, 621. 

 Productive coal-fields, 624. Coal, 630. Extent and relations of 

 coal-beds, 637. Varieties of coal, 637. Iron ore, 638. Geo- 

 graphic conditions in the eastern interior, 639. Duration of the 

 period, 640. Close of the period, 641. Carboniferous forma- 

 tions in other continents, 641. 



LIFE OF THE PENNSYLVANIAN PERIOD 643 



Plant life, 643. Climatic implications of the coal-plants, 651. 

 Land animals, 652. Fresh-water life, 655. Marine life, 656. 



CHAPTER XXII 



THE PERMIAN PERIOD 



FORMATIONS AND PHYSICAL HISTORY 660 



East of the Mississippi, 660. West of the Mississippi, 660. Corre- 

 lation, 662. In Europe, 662. Other continents, 666. Permian 

 glacial formations, 666. Close of the Paleozoic era, 668. 



LIFE OF THE PERMIAN * 668 



Impoverishment of life, 669. Plant life, 669. Land animals, 672. 



Fresh-water life, 674. Marine fauna, 674. 

 PROBLEMS OF THE PERMIAN. . 677 



