LIST OF ILLUSTRATIONS. 



Pagb 



Fig 1. Lichen and crevice plant societies on shore rocks. 



Potentilla tridentata as crevice plant 22 



Fig. 2. Bog of drained depression type. Sedge zone in foreground . . 22 



Fig. 3. Nesting habitat of stone roller 26 



Fig. 4. Nesting habitat of horned dace 26 



Fig 5. Prairie chicken, TympcmacTius americanus 90 



Fig. 6. Diagram showing the development of a relic dune 112 



Fig. 7. Grand Tower limestone in backbone ridge, Jackson county, 



Illinois 118 



Fig. 8. Upper portion of Grand Tower limestone showing contact 



with the Hamilton 118 



Fig. 9. Map of area disturbed by earthquake. May 26, 1909 133 



Fig. 10. Sketch map of Northwestern Illinois 144 



