SANDUSKY FLORA. 



sorts, each having its characteristic plants, while many 

 species not known to grow farther east in the state are 

 found on both of them. 



Extending over the greater part of the township of 

 Oxford, and over portions of the townships of Milan, 

 Huron, Perkins, Margaretta andGrotonis a nearly level 

 prairie which probably at one time formed the bottom 

 of the glacial lake that preceded Lake Erie and later of 

 a bay or bays partly shut off from the lake by sand 

 bars which still exist. Underlying most of this prairie 

 is the Ohio shale, which in man}' places is close to the 

 surface. The ground requires tiling to produce good 

 crops. The other prairie lies north and west of the 

 village of Castalia, extending to the western boundary 

 of the county. The soil of this is different from the 

 other, being a calcareous deposit from the water of the 

 Castalia springs. Within the memory of men still 

 living a great deal of this prairie was under water 

 much of the time. A considerable portion of the region 

 extending south of Castalia for a distance of over fifty 

 miles has no surface streams, but the water descends 

 through the joints of the limestone and flows through 

 subterranean passages which it has made in the soluble 

 rock of the Waterlime formation. This water charged 

 with lime carbonate issues from the ground in numer- 

 ous bold springs in the vicinity of Castalia, which owes 

 its name to this circumstance. These springs are the 

 largest and most beautiful in Ohio. The slope from 

 Castalia to Sandusky Bay is very gradual and before 

 any artificial drainage was established, the region was 

 a marsh filled more or less with the calcareous water 

 whose deposits have formed over thousands of acres to 

 a depth of many feet. In some places these deposits 

 are indurated forming a tufa, in others, soft making a 

 shell marl containing theremainsof millions of Limnea 

 and Planorbis of the same species as live in the bay 

 now. The tufa is composed mostly of petrified Chara 



