Topography of the Valley of the MusTcinguin. 11 



The summit level of the Ohio canal is three hmidred and ninety- 

 three feet, above low water mark at the mouth of the Muskingum, 

 while the tops of some of the adjacent hills are at an elevation of 

 nearly one hundred and fifty feet more, making the highest lands 

 between Lake Erie and the Ohio river to be four hundred and fifty 

 three feet, above the water at either of those places ; there is a dif- 

 ference of only two feet between the level of the mouth of the 

 Muskingum, and the lake ; the latter being lower by two feet. 

 When compared with the ocean, the hills on the heads of the Musk- 

 ingum, are at least one thousand feet above its tide ; a meridian line 

 from the mouth of the Muskingum, would pass a little east of the 

 summit level, from which spot, there is sufficient descent to cause 

 a rapid current in the water, and when urged on by an accumula- 

 tion of power from the sudden rise of the streams, the torrent be- 

 comes capable of levelling all obstructions that may oppose its course, 

 tearing up the sandstone rocks, and shales down to its present deep 

 and tortuous bed, amongst the hills which cluster along its borders. 

 From the termination of the sandstone rocks, to the westerly heads 

 of the river, a distance of not less than sixty miles, boulders and 

 fragments of primitive formations are found scattered over the sur- 

 face of the earth. They ar^ however, not confined to the surface, 

 but in sinking wells, at the depth of seventy feet, the same varieties 

 of water worn and rounded fragments are found. They are of all 

 sizes, from a pound weight, to that of several tons ; and they are 

 found through the tertiary deposits from the N. E. line of the Ohio, 

 to the jNIississippi river. I have now before me a fragment of a 

 large boulder from the " Grand prairie" in Illinois. The early set- 

 tlers of these regions observing their singular appearance, and entire 

 dissimilarity to that of any local or known rock, gave them the very 

 appropriate name of " the lost rocks." They are most commonly 

 seen in solitary masses, but sometimes in groups of several hun- 

 dreds, as if deposited from powerful currents, or streams of water 

 suddenly arrested in their course. The fragment before me is com- 

 posed of feldspar, mica and hornblende. The feldspar is nearly 

 white, and is the most abundant material. The mica is in plates of 

 from one eighth to a twelfth of an inch in diameter, color, black, or 

 that of very dark smoke, and it composes one eighth part of the 

 mass. The hornblende is in grains, fi'om the size of a mustard seed 

 to that of half a grain of wheat, and very uniformly diffused, and its 

 cohesive power is rather weakened from long exposure to the at- 



