VALLEY OF THE OHIO. 133 



all the formations of tlie northern part of the continent, a 

 great natural cabinet at once rich, confused, and instructive. 

 Its multifarious specimens may be arranged in the following 

 manner : 



1. Fragments of fossil wood, which have been dug up at 

 various depti)s, from ten to ninety feet. They are not mi- 

 neralised, and appear to have belonged to trees of the same 

 species with some of tiiose which grow in our existing fo- 

 rests. I iiave not detected among them any tropical plants. 



S. Grey, siliceous, and calcareous sand, which composes 

 a great portion of the plain, and has probably resulted from 

 the destruction of arenaceous limestone rocks, many strata 

 of which exist in this country to the north and east. 



3. Veins of blue and yellow clay, afforded no doubt by 

 the marl, which in many parts of the limestone tracts, sepa- 

 rate the laminse of that formation. 



4. Holled and angular fragments of blue shell limestone, 

 detached from the strata of the surrounding hills. Many of 

 these are large tabular masses, and seem to have been 

 brought only a short distance. None of them indeed could 

 have come down the river more than one hundred miles, as 

 this variety does not extend beyond that limit to the east. 

 They are very numerous. 



5. Polished debris of tliat kind of grey sandy limestone 

 which tlie Sciota and Little Miami rivers traverse near their 

 sources, and which have evidently been rolled hither by the 

 copious streams that formerly flowed in the valleys of those 

 rivers. These fragments are as numerous as the last.* 



6. Rubble and boulders of grey variegated and micaceous 

 sandstone, with minute fragments of coal, aluminous slate, 

 and shivers, generally rendered smooth by attrition. These 

 are from the country up the Ohio, where such strata are 

 found in place. They are not so numerous as the two last. 



7. Foreign or adventitious debris, consisting of granite of 

 different colours, gneiss, micaslate. hornblende, sienite, xvacke, 



• These, on account of tlie whiteness of the lime into which they burn, are 

 collected and used for that purpose. 



