191 



The sand plains succession may be regarded as fairly repre- 

 sentative of succession on unconsolidated rocks. It differs in 

 some respects from succession on gravel and clay, but so far as 

 the sequence and composition of stages is concerned the resem- 

 blances are greater than the differences. Just as was found in the 



Fig. 8. Pitch pine forest; Farmington. The undergrowth is largely xero- 

 phytic, common shrubs being Ceanothus americana, Corylus americana, Myrica 

 asplenifolia, Quercus ilicifolia and Rhus glabra. 



case of consolidated rocks, the chief difference between various 

 uncompacted rocks in their effect on succession concerns the 

 quickness or slowness with which mesophytic conditions are 

 attained. The presence of clay in a soil increases its ability to 

 retain water and thereby favors the more rapid advent of meso- 

 phytism. The most favorable of all soils in Connecticut, from a 



