. r >4 THE PLANT LIFE OF MARYLAND 



in the conditions, due to physical agencies and to the vegetation 

 itself result in a gradual replacing of the earliest plant covering by 

 successive different ones. As respects their physical conditions im- 

 portant to plant life, new habitats due to shore-line changes fall into 

 two classes, a — those arising from the deposition of fine material in 

 the shallow water of inlets and coves, b — those arising from the 

 building up of reefs or liars of coarse soil, which takes place only on 

 the shores of larger bodies of water where wave or tidal action is 

 vigorous. The first of these classes embraces salt or brackish 

 marshes, the second the fringing-reef of the ocean front, and hooks, 

 spits and bars such as may be found at Roaring Point in the N" anti- 

 coke River, at Castle Haven in the Choptank River, and at, Lloyds 

 Creek in the Sassafras River. The character of the material of 

 which now features consist and the level to which they are built 

 above tide determines their soil-water conditions, which in turn de- 

 termine the occurrence of salt marsh, brackish marsh, strand or dune 

 vegetation. A secondary result of deposit along shore-lines is the 

 formation of bars which cut off small inlets from the main body of 

 water as has occurred at a number of localities along the Chesapeake 

 Bay in Kent and Anne Arundel counties. The conditions become 

 gradually changed from salt to fresh in these so-called "relic ponds." 



MINERALOGY AND Sons. 



The relation in which the soil stands to plants is thai of a store- 

 house of water and raw food materials. This causes all of the 

 characteristics of the soil which have to do with the presence and 

 availability of both the water and its dissolved substances to be of 

 great importance in the physiology of the plants occupying the soil, 

 and the differences in the physiological character of different plants 

 causes these soil conditions to play a very important role in sorting 

 the species which make up the flora of a given area. In other words, 

 soil conditions are responsible for the distribution of plants in small 

 areas with uniform climate. The fact has already been pointed out 

 that the topography often operates in determining the water content 

 of soils, yet it is only one of many factors which lie at the base of 

 the characteristics of the soil. The direct importance of soils to 



