28 



SMITHSONIAN INSTITUTION 



f 





Fig. 27. — A typical exposure of bed-rock on the western Atichigan shore. 

 Little Traverse Bay, Michigan. Because of the local structure the geologist 

 has only to follow the shore-line to determine the entire sequence. (Photo- 

 graph by E. R. Pohl.) 



l'i(.. _'8. — All (lulcrop of Alishi.ssippian black .shale on the shores of Lake 

 Michigan near Norwood. Mich. By comparison with Fig. 51 of Sinithsoiiian 

 Explorations and Ficld-JJ^ork in 1926 the similarity of these beds with those 

 of Ontario can be seen although 300 miles separate the localities. (Photo- 

 graph by E. R. Pohl.) 



