322 



The Ohio Naturalist. 



[Vol. VIII, No. 6, 



If the shore Hne of the Dune Section were advancing towards 

 the Lake there would in all probability be a corresponding ad- 

 vance of the Ouercus vehitina-imbricaria Forest Formation over 

 the dunes towards the east but, as conditions are at present, 

 there seems to be only in a few places any real advance made by 

 the oak forest and, practically, a state of equilibrium mav be 

 said to exist as to this phase of the question. 



Fig 10. A dune controlled by the Prunus virgiyiiana Consocies of the 

 Prunus-Rhus Dune Thicket Formation. Note secondary species: Juni- 

 perus virginiana, Asclepias syriaca, Panicum virgatiim. In blowout sur- 

 rounding dune note Panicunt virgatum, Salix interior. This dune appears 

 in distance in left third of preceding illustration. 



Towards the northern portion of the Dune Section the grass 

 dune formations are followed by a formation consisting of ever- 

 green shrubs with northern phytogeographical relationships, this 

 formation being termed: 



The Arctostaphylos- J uniperus Heath Formation. 



This formation, once established on a dune, brings about more 

 stable conditions than does the Prunus-Rhus Thicket Formation. 

 The vegetation being evergreen the winter winds are obstructed 

 much more than is the case with a deciduous dune vegetation 

 and not only are more stable conditions brought about but more 

 sand is deposited by the wind. The structure of this formation 

 is as follows: 



