- 1876.] Plain, Prairie, and Forest. 579 
f; 
The prairie is a heavily-grassed area, destitute of forest growth, 
but existing in the midst of a wooded region, where the clima- 
tological conditions are favorable to the growth of timber, but 
where some other cause than the want of sufficient moisture has 
operated to prevent this growth. To illustrate how character 
and distribution of forest and prairie are independent of climato- 
logical conditions, let us take the State of Wisconsin, which has 
an area of about fifty-four thousand square miles, the ninetieth 
meridian passing nearly through its centre. The northern por- 
tion of the State belongs among the most densely wooded regions 
in the country. This heavily-timbered belt extends from Lake 
Superior south to the forty-fifth parallel. The sugar-maple is the 
predominating tree. South of this is a region of pines, not as 
thickly crowded together as are the trees in the region to the 
north, but constituting fine forests ; still farther south, and occu- 
pying the whole area south of the Wisconsin River, is a region of 
mingled forest and prairie, the trees being chiefly oaks. The 
cause of this peculiar distribution of the timber in Wisconsin will 
be noticed farther on; at present it is only desired that the atten- 
tion of the reader should be called to the entire want of harmony 
of this arrangement of forest and prairie with the climatolog- 
ical conditions. The Smithsonian charts show a greater amount 
of precipitation over the prairie area than anywhere else in the 
ta y no amount of ingenuity can the peculiarities of the 
isothermal or isohyetal lines be made to play in with the marked 
differences of the vegetation. 
Equally striking are the changes which are met with as one 
Passes from the State of Indiana into the adjacent one of Illinois. 
e former of these is forest-covered, woodlands extending over 
probably as much as seven eighths of its area; Illinois, on the 
Other hand, is par excellence the prairie State, not more than a 
quarter or at the most a third of its surface being covered with 
timber, Here, again, there is nothing to coincide with the dis- 
tribution either of rain or of temperature; the division seems a 
Purely arbitrary one until looked at in the light of geology. 
hese are only two instances, out of many which might be cited, 
going to show the absence in certain regions of any essential 
®onnection between climate and distribution of forests, and these 
are sufficient at any rate to indicate the desirability of inquiring 
What other causes may exist, determining, at least to a considera- 
ble extent, the curious intermixture of grassed and timbered 
‘teas which we find in the prairie region proper. 
