~I 
BIG SPRING PRAIRIE. 
CLIMATIC CONDITIONS. 
Big Spring Prairie is crossed at two points by the 
forty-first parallel, which forms the boundary line 
between Wvyandot and Seneca counties. By reference 
to Map 1, it will be seen that almost equal parts of this 
prairie lie on either side of this line. It is about forty 
miles south from Lake Erie and about twenty miles 
north from the Ohio River and Lake Erie divide. The 
extremes of temperature are slightly greater here than 
directly along the lake shore. ‘This, in part, may ac- 
count for some of the differences in vegetation of the 
Big Spring Prairie and the Castalia Prairie near Lake 
Erie. In the Spring, the vegetation which has begun 
active growth during a few premature warm days, is 
more likely to be injured by frost than the more tardy 
vegetative growth of the lake region. In the Autumn, 
frosts occur earlier than in the lake region. Further- 
more, on the low lying prairie with its moist black soil, 
frosts occur later in Spring and earlier in Autumn than 
on the ridges around it. 
1. PHYSIOGRAPHIC.—GEOLOGICAL FORMATIONS 
SURROUNDING PRAIRIE AND CHARACTERISTIC VEGE- 
TATION OF SAME. 
The Niagara Limestone is the native rock which 
underlies the western part of Wyandot and Seneca 
counties and the eastern part of Hancock county. 
The surface of these counties is quite level, moderate 
hills occurring only along the larger natural water 
courses. As there are no important natural water 
courses in the vicinity of the Prairie, the country is a 
rather level plain with the exception of an interesting 
and remarkable outcrop of Niagara Limestone. This 
