203 



NINETEENTH REPORT. 



This calcium carbonate content varies from one to five per cent. The 

 dune sand is also characterized by a very unequal distribution of organic 

 material, in the presence not only of old soil lines, but also of individual 

 plant parts and of patches of dark material, apparently carbonaceous, 

 with rare ferruginous ^patches, and also marly layers, indicating 

 apparently the location of former pannes. The surface of the glacial 

 deposits is mainly outwash, consisting of sand with more or less gravel, 

 and even boulders, and with occasional exposures of clay layers. 



The moisture content of the soil varies with the location and with the 

 character of the substratum as shown in the following table: 



Table I. 

 Relation of Character of Substratum to IMoisture Content. 



III. ECOLOGY. 



(Fig. 11.) 



A. Climax forest. The wliole region, including at least part of the 

 moving area, was originally covered by a heavy climax forest, 

 (Plate VIII), which is still practically untouched in the southern tip 

 and along most of the eastern edge of the dunes. The level ground on 

 the Bar has largely been cleared, and is covered with second growth of 

 foi^st trees and clearing pioneers, where not occupied by summer 

 cottages. The climax forest is composed of beech, maple, and hemlock, 

 with much yellow birch. The trees are tall and slender with close stand 

 and very little undergrowth, where undisturbed. Occasional specimens of 

 Quercus rubra, Pinus Strobus, and Pinus resinosa are found. Among the 

 shrubs, Acer spicatum, about at the southern limit of its range. Viburnum 

 acerifolium and Taxus canadensis are conspicuous. Characteristic species 

 in the undergrowth are Aralia nudicaulis, Streptopus roseus, Clintonia 

 borealis, Aralia racemosa, Maianthenium, I.innaea borealis and Mitchella 

 repens, witli Aspidium sjDinulosum, Adiantum pedatum, and Botrychium 

 virginianum. 



