113 



encroaching upon the Solidago. There is a cUfference of about 1.5 

 feet (5 chn.) in the upper and lower levels of the Polytrichum zone, 

 and the Solidago association is somewhat broader vertically. The 

 deepest part is about 16 feet (5 m.) above the drainage level 200 

 yards (200 m.) away and all the intervening territory is sand. The 

 mesophytic nature of the association must be due to the action of 

 the moss in developing- a retentive layer of humus, rather than to 

 any feature of drainage. 



Blowout C is small and flat and most of it is occupied by a dense 

 carpet of Polytrichuui, with many low shrubs of Salix pcdicellarls 

 and some seedlings of Populiis deltoides. The surrounding zone 

 consists chiefly of Solidago grauiUiifolia and Lcspedcza capitata. 

 This blowout is about 12 feet (4 m.) above the drainage level and 

 about 6 feet (2 m. ) above the cultivated field just east of it. It is 

 14.5 ft. (4.8 m.) below the crest of the deposits of blowout D at 

 the west. 



D is a larg'e blowout still active on the north, east, and west. 

 A low oblong area enters the blowout from the southwest and is 

 now almost entirely stabilized. J\Iost of this represents a recent 

 deposit of sand from the rear, but the deepest part, nearest the cen- 

 ter of the blowout, is the extinct basin. It is now 11 ft. (3.3 m.) 

 below the crest of the deposits. In this basin both the Salix and 

 Solidago associations are now developing. The latter is represented 

 by a plentiful growth of Solidago graiiiiiiifolia and Aristida tuber- 

 culosa, with some J uncus acuuiiiiatus; the former by abundant young 

 plants of Salix longifolia, with Ludvigia palusfris, some small plants 

 of Pauicum virgatuiu, four or five plants of Populus deltoides, and 

 four lumches of Scirpus cypcrinus. The sand is wet and well cov- 

 ered with a layer of dead vegetable matter. 



On pure sand back of this basin and 6-12 inches (1-3 dm.) above 

 it is a mixture of the Solidago and Polytrichuui associations. 

 The ground is partially covered with dense or open mats of 

 Polytrichuui, with Hypcricmn gentianoides, RJicxia virginica, Juncus 

 acuniinatus, Polygala sauguinea, and seedlings of Salix pedicellaris. 

 Solidago graminifolia and Aristida tuberculosa are abundant, but 

 as usual are conspicuously smaller when growing on the moss mats. 

 Rlicxia may live in the middle of the mats, but Hypericum gentian- 

 oides gTOws only in the bare sand in the immediate vicinity of the 

 moss. 



Each of these parts of the blowout illustrates early stages in 

 the development of the associations, before their zonal relations have 

 been established. The Salix association apparently demands moist 



