PAL.E0NT0L0GICAL REPORT OF GEOLOGICAL SURVEY. 



555 



the proof that they have been destroyed by subsequent erosion? The 

 proof is found in the quaternary formations, all along the Ohio and 

 the Mississippi rivers. The loam deposited by these rivers is some- 

 times mixed with broken and rolled pieces of coal; there are even 

 some deposits of alluvial rolled coal, or pebbles of coal, heaped in 

 strata in such a way that they have been taken, by unexperienced ob- 

 servers, for true coal beds. I had opportunity to examine one at low 

 water of the Ohio river, below Vevay, Ind., in an alluvial formation, 

 just upon the Lower Silurian Measures, and I have heard of some oth- 

 ers. 



But here we must close this already too lengthened discussion, and 

 let the reader draw his own conclusions from the facts enumerated 

 above, and also apply the general rules to the different localities open 

 for his examination. There are, no doubt, some phenomena of the 

 formation of the coal that are not yet satisfactorily explained, and some 

 local accidents which will baffle every effort toward a generalization. 

 But the science of the coal is still new, especially in the United States, 

 where the coal-fields have been till now regarded only as true mines of 

 wealth, very good for working, but scarcely worth a careful scien- 

 tific study. 



