70 



SEVENTH REPORT. 



saccharinnm and with them Carpiiuis and Hamamelis. There are also 

 shrubs which belong to the oak-hickorj- forest, Corniis floridus, Prunus 

 Virginiana and the oak and hickory have invaded from the bank. 



The arrangement of plants on an established bank is better shown in 

 the diagram, 50 feet high, 120 feet long. This bank is 66 feet above level 

 of the river. 



The highest parts are covered by the oak-hickory forests spreading 

 over bank. It soon meets the zone of ravine plants, elm, basswood, Ham- 

 amelis and the herbs, Thalictrum dioicnm, fern, etc. There is a struggle to 

 hold the bank and the oak-hickory is gaining ground. Below this the 

 slope is wet by hillside springs and forms a bog which has a characteristic 

 flora. The soil is black humus with much organic matter and with much 

 lime a few feet below the surface. Still lower, quicksand is found. The 

 plants which grow here are Tilia Americana Fraximus Americana, Cra- 

 taegus, Ribes, Xanthoxylum Americana, but most abundant Spathyema, 

 sedges, mosses, Cardamine bulbosa, Eupatroium, purpureum. Lobelia 

 sylphitica, Galium asprellum, etc. 



Its position suggests that this bog may not have been a part of ravine 

 development, but may have been swamp or lake bottom when the river 

 stood at different level. Mastodon bones found in similar place a quarter 

 of a mile further point toward ancient origin. 



The succession of groups of plants is shown by chart. 



I Gulltj 2Voun3 Rgvllfc 3WeH Develq^ir A F^avifie U Old. F^Qvirp. 



5 E>fqbliit\edL£ar^. 



f7 77\ ^•k) 



1 »^ PU.tl 

 ..**,r* Pu-t, 



Succession of Plants on Sand. 



■5 «.-.», r»..T, 



Fig. 1. — Charts showing the succession of plants in the development of ravines in cLiy and sandy soil. 



