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south, range four west. Following thence along the western border of 

 the carboniferous series, the formation is to be found occasionally over 

 Kmited areas, through towns six and seven south, range four west, Hills- 

 dale county, and towns six south, range five and six west, and towns five 

 south, range six and seven west. Branch county. In the former county 

 it is found in close proximity to the overlying sandstone, but in the- 

 latter with a considerable interval between, and generally in limited 

 bodies, which appear to be but relics left in place, after the destruction 

 and removal of the greater part of the formation. 



The ore consists of nodular masses, formed of concentric coats or 

 layers of iron, combined with lime and alumine, and surrounding a hard 

 nucleus which frequently contains fossils. These masses are often of 

 many pounds weight. They are imbedded in a gray, micaceous clay, 

 «f rery fine grain, and frequently so hard as to have the appearance of 

 «onipact sandrock. They are in general arranged in strata, alternating 

 with the beds of clay, but are often found dispersed through the mass. 

 This ore is analagous to that which is worked exxtensively, and with 

 profit, in Ohio. 



The clay is very free from lime, and of even texture. It is in conse- 

 quence, admirably adopted to all purposes of the kiln or pottery, and is 

 far superior to any found elsewhere in the State. 



As a portion of this formation, in Branch county, was made the sub- 

 ject of a special examination, in accordance with an act of the Legisla- 

 ture of last winter, it will be unnecessary for me to add any thing to 

 those practical considerations which will be as fully exhibited by you, as 

 their importance demands. 



No means were presented for ascertaining the thickness of this for- 

 mation. At the village of Branch, it has been penetrated in a well, 

 twenty-three feet. 



III. FOSSILIFEROUS, FERRUGINOUS SANDSTONES. 



Next overlying the clay and ironstone, in Hillsdale county, succeeds 

 a series of ferruginous sandstones, containing numerous marine fossils. 

 Though classed in the so called "carboniferous formation," these all oc- 

 cupy a position below the lowest of the coal l)eds, and a short distance 

 below their associated sandrocks, which present impressions of plants of 

 the carboniferous era. 



