198 GEOLOGY OF EASTERN WISCONSIN. 



MAGNESIA. LIME. 



Per cent Per cent. 



Oak, body wood 4.8 73.5 



Oak, small branches with bark 7.5 54.0 



Poplar, young twigs 7.5 58 . 4 



Elm, young twigs 10.0 37.9 



Elm, body woo d 7.7 47.8 



Linden (Bass wood) 4.2 29.9 



Apple tree 5.7 81.0 



Apple tree, entire fruit 8.8 4.1 



Beech 45.8 16.8 



White pine 5-9 50.1 



Larch 24.5 27.1 



The percentages relate to the ash of the plant. 



For other facts of similar import, see the work cited above. These 

 facts go to show that magnesia is more concerned in fruit produc- 

 tion, and lime in the formation of fiber. In view of this it may be asked 

 whether the well known superiority of Wisconsin wheat is not due to 

 the magnesiaii element in her soils. 



If we compare the map of soils with the map of vegetation we 

 shall find some interesting and important relations. The Prairie 

 Loam is of course covered by prairie vegetation. The Lighter 

 Marly Clays are chiefly occupied by the oak group, the Heavier Mar- 

 ly Clays by the vegetal groups in which the maples are prominent, 

 The Red Marly Clay by very much the same; the Limestone Loam 

 by the maple, beach and conifers in the peninsula and chiefly by the 

 oaks elsewhere, this difference being due probably to climatal influ- 

 ences; the Silicious Sandy soils by the conifers chiefly ; the Calcareous 

 Sandy soils by the maple and oak and the maple and beech groups. 

 The Humus soils are occupied by the several classes of swamp vege- 

 tation. Where a patch of heavy clay occurs in an area of the lighter 

 class it usually sustains heavy oak timber, especially white oak, 

 rather than the " openings," and where the reverse is true, the oak 

 and maple group usually displaces the other maple groups. The 

 pine is frequently found on soils that are quite decidedly clayey in 

 nature, but in many of these cases a substratum of sand is to be found 

 within a few feet of the surface. 



These correspondences, which are susceptible of being carried out 

 to much greater detail, illustrate the mutual relations of soil and na- 

 tive vegetation, and open to the agriculturist a wide field for profit- 

 able study. 



