358 



HOTANICAL SURVEY OF DISMAL SWAMP RKCJION. 



SOIL ANALYSES. 

 Table B.— Mechanical analyses of soils and subsoils. 









>, 







i- 



T3 i — 1 



T 





>- 





No. 



Locality. 



Description. 



-• 



•fa 

 'cs a. 



So 



*a 



•4-> 



/ 



o 



i 



= 



- 



'- 



bt 



■■- 



a 

 3 



"3 



cS 





PI ■ 



"a 

 a? 



I 



DO 



a ■ 



Kg 



a a 



rH 



q 



49 



--' 



.—i 



11 



tn 



o 

 2 



sa 



- a 









P.rt. 



Z 

 P.rt. 



S 



o 



P.rtf. 



fa 

 P.ct. 



r> 



00 



fa 



/ ,1 



_■ 







Inches. 



iVf. 



P.rf. 



P.ftf. 



P.r.t, 



3921 



(1 mile west of 

 ' Wallaceton, Va. 



| [ 0-20 



1.72 13.10 



T. 



1.3H 



2 75 



34.1519.78 



10.01 5.21 11.60 



at«2 



} Virgin soil ..-{20-40 



1.24| 3.30 



T. 



.20 



1.45 



34.05 20.23 



10.93 4.83i23.35 



3923 



1 Edge of swamp. 

 [Wallaceton, Va., 

 J 300 yards west of 

 1 Dismal Swamp 

 I Canal. 



1 |li) ii' 



.961 1.90 





.15 



2.00 



47.3019.25 



7.95 3.0316.65 



31129 



1 In corn for 201 0-24 



1.32 6.90 



T. 



.95 



7.75 



50.53 8.68 



7.70 4.42 



1 1. 10 



39311 



[ years eon-<24-44 



1.22 2.40 



T. 



1.13 



5.63 



50.13 9.15 



7.61 3.9618.65 



3881 



tinuously. J44-60 



1.00 1.40 



T. 



.03 



4.88 



58.10 8.78 



4.82 2.82 



16.50 



3924 



| Wallaceton, Va.. 

 1 100 yards cast of 

 | Dismal Swamp 

 I Canal. 



Moan of above. 



West Norfolk, Va. 



j In corn for 501 0-21 



.hi r,. hi 



T. 



1.15 



7.25 54.45 8.20 



10.68 3.16 



7.80 



:fl »;.'.. 



\ years con-j21-40 



.97 



2 In 



T. 



.!«) 0.40 



48.38 6.15 



12. 13 



3. 35 



18 40 



3926 



tinuously. [40-00 



.<X, 



l.ll 

 .50 



1.00 

 4.13 



T. 



.50 3.25 



. 77 4. 60 

 . 46 IS, 28 



67.95 8.80 



49.4512.11 

 53.83 5.84 



2.80 



8.211 

 6 IE! 



1.05 



3.65 

 4~39 



12.35 





T. 



0.04 



15. 16 





Finest truck land, 



357 



1.00 



8 78 







9-18 inches. 



















302 



Champaign, 111 



Prairie soil . 







1.04 



1.98 G.K5 



6.23 1 5.82 



28,38 



15 46 



30 IK) 



3928 



Wallaceton, Va.,1 

 mile north. 



Sand dredged from 

 canal, 10-14 feet. 



.17 



.20 





. in 1.73 



79.0016.25 



.82 



.07 



.15 



3933 



Lake Drummond, 



Sand bored from 



.48 



2. 12 



T 



6.7939.69 



15.0715.32 



6 113 



3 Hi 



11 fltf 





Virginia. 



bottom of feeder 

























12 feet deep. 













1 









THE PLANT COVERING OF THE REGION: ITS PHYSIOGNOMY AND 



ECOLOGY. 



One of the most important functions of plant geography is the 

 description of the vegetation of each floral region as it actually 

 occurs in nature, apart from the systematic relationships of the 

 species and the historical-geographical affinities of the whole flora. 

 A word picture is given of the facies or physiognomy of the plant 

 covering as a whole, and of the various assemblages of species — 

 formations and associations — which occupy the different soils, over- 

 lying the several geological formations. In the Dismal Swamp region, 

 owing to the uniformity of its geology and the comparatively slight 

 physical and chemical differences of its soils, the principal factor in 

 effecting a differentiation of the plant formation is the nature of the 

 drainage. Only the plant growth of areas bordering immediately 

 upon salt water is affected to any great extent by the chemical com- 

 position of the soil. Elsewhere it is chiefly a question of whether the 

 substratum possesses a greater or less water content. 



In order to an intelligible description of the physiognomy, a classifi- 

 cation of the several plant assemblages of the region is necessary. 

 The following arrangement appears to be, on the whole, the most 

 simple and logical. It must not be supposed that the natural limits 

 of the formations and associations are sharply defined. On the con- 

 trary, between neighboring assemblages there is usually a debatable 

 ground, which might be reckoned 1o either. Tims the forests of the 

 plain pass by insensible gradations into the xerophile woods of the 

 inner strand on the one hand, into hygrophile forest or wooded swamp 



