92 NINTH REPORT. 



staphylos Uva-ursi, Gaylussaccia resinosa, Vaccinium Pennsylvanicum and 

 Sibbaldiopsis trident ata. Very common tenants, promiscuously scattered, 

 and in this locality of no consequence as soil-binders, are such grasses as 

 Ammophila arenaria, Elymus Canadensis and Cakile edentula. Occasion- 

 ally found are Amelanchier botryapium, A. rotundifolia, Diervilla diervilla, 

 and now and then Unifolium Canadense, Lathyrus maritimus, Echinochloa 

 Crus-galli, Equisetum arvense, and Rosa Sayi. 



The Jack Pine is the most abundant tree, and flourishes best in these 

 xerophytic places. Whitford (17) has suggested that a definite deciduous 

 society is finally developed upon dunes and sandy beaches. It seems as 

 if the mixed forest types further west along the shore, and those on the fossil 

 beaches farther inland were indications of dunes having passed to this stage. 

 Near the Catholic cemetery the undestroyed Norway pines in the young 

 Jack pine forest indicate, perhaps, that this fossil beach had formerly a mixed 

 forest. Changes in water level remaining high or low for a prolonged time 

 (due to periods of greater or less rainfall or changes in drainage) might dis- 

 place the original flora or give rise to a heterogeneous flora. But whether 

 this suggestion is in accordance with the observed facts is difficult to say. 

 For, in many places where the soil conditions are unfavorable up to a certain 

 limit, the region is certain to have indefinitely a Jack pine aspect. How- 

 ever, it is not the nature of the soil alone which determines that the Jack 

 pine should predominate or be succeeded. The nature of the soil water as 

 determined by the character of the underlying layers, and the ability of this 

 soil to retain water, must be considered as one of the most important of the 

 secondary factors influencing distribution. 



Swamps. — The dunes, formerly fixed, have been rejuvenated by the com- 

 plete removal of mature timber, and are now encroaching more and more 

 inland upon the swamp, partly by actual advance in that direction and the 

 formation of new dunes, partly because of wind and wave action during the 

 storms of autumn. In some places the sand has covered the swamp to a dis- 

 tance of 30 to 40 feet, showing from 6 to 7 wave-action debris lines. 



The area of the swamp is extensive, low, not well drained, and caused 

 either by a general sinking of the beach or a raise of water level due to exces- 

 sive rainfall, evidences of which are clearly seen in the submerged and partly 

 buried trees standing along the lake shore, or perhaps by bars and spits 

 forming across embayments. The silting up of the mouth of Dead River by 

 the wash of the surrounding soil and the accumulation of vegetation may 

 further have hastened the process. This low and wet area is now inhabited 

 by a swamp flora whose zonal arrangement is more or less complete but not 

 always continuous. Since the zonal distribution in swamps is well known 

 the various zones occurring need be mentioned here only briefly. 



Starting as ponds or lakes with a multitude of water lilies, bladder-worts, 

 water-milfoil and other pond plants predominating, most swamps are bor- 

 dered by the bulrushes (Scirpus lacustris, S. subterminalis, S. cyperinus), the 

 swamp cinque-foil (Comarum palustre), Typha latifolia, and others, with 

 sedges like Carex oligosperma, C. Sterilis and C. filiformis encroaching upon 

 the water in the form of a quaking mat. This mat becomes firmer shoreward. 

 Gradually the surface is built up above water level, the decay of these plants 

 preparing the way for another succeeding zone, the Cassandra-Sphagnum 

 vegetation — the true bog flora-comprising cotton-grass (Eriophorum alpi- 

 num, E. gracile, E. polystachyon), Andromeda polifolia. Ledum Groenlandi- 

 cum, Sarracenia purpurea, Pyrola uliginosa, Drosera rotundifolia, D. inter- 

 media, D. linearis, Oxycoccus oxycoccus, Solidago uliginosa, Dryopteris 



