16 



INTRODUCTION. 



General Sequence op Carbonifeeous Rocks in North America, 



CaRB0NIFEE0T7S 



r rSandstones, shales, conglomerates, and lime- 



Ooai ixLeasures { ■ i i i n i i • 



I stones, with beds of coal and iron ore. 



rPebble beds, sandstones, conglomerates, and 



\ grits. 



Millstone Grit. 



SUB-CABBONIFEEOTTS 



Chester Group Limestones in beds, shales, and sandstones. 



. _, f Limestones, calcareous shales, and arena- 



St. Louis Group { ,. 



I ceous limestone. 



•( Keokuk G roup Limestones with chert. 



Burlington Group . . . Limestones with chert. 



„. , , , ^ rSandstones, grits, and shales, with thin beds 



Kinderhook Group ..A . ,• • ,• 



I 01 oolitic limestone. 



