EXPLANATION OP THE PLATES. 155 



PLATE XI. 



Pig. 1. View of eroded hills, near Natal, in South Africa. Drawn by Mrs. Lydia B. Grout. 

 Fig. 2. Erosions on Mamana river, South Africa. Drawn by Mrs. Lydia B. Grout. 



PLATE XII. 



Pig. 1. Ideal section of a terraced valley. 



Pig. 2. Sections across the Connecticut valley, through Mettawampe. 

 Pig. 3. Section across the Genesee valley, at Portage. 

 Pig. 4. Sectiou to illustrate the position of an ancient beach. 

 Fig. 5. Valley of erosion in Dorset, Vermont. 



Fig. 6. View of Sandalwood Island, in the East Indian Archipelago. Drawn by Rev. Charles 

 Hartwell. 



Fig. 7. Valley of erosion, in New Fane, Vermont. 



Pig. 8. Denudation at Cincinnati. 



Fig. 9. Canon of Chelly, in New Mexico. 



