16 



Geology of the Musldngum Valley. 



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shells, but In many places, abounds in cubic crystals of sulphuret 

 of iron. Some of the calcareous deposits are dark colored and 

 decompose into a marl on exposure to the air, and all have a 

 tendency to crack and break into rhombic fragments, as they lie 

 in their beds. The sandstone rocks are more coarse, and are also 

 destitute of the casts of fossil trees, found so abundantly in the strata 

 of rocks in the vicinity of Zanesville, and on the waters of Moxa- 

 hela creek in Perry county. Coal deposits are more rare, and the 

 beds thin and shaly- There are numerous beds of red and light 

 blue marl of a schistose structure, lying under thick deposits of sand- 

 stone; they are filled with the impressions of fossil plants, general- 

 ly of the genus Sphenoptera, affording decisive evidence of a con- 

 comitant and exuberant vegetation, analogous to that of the carbon- 

 iferous group ; although from some cause, the materials for coal were 

 furnished much less abundantly than in many other parts of the val- 

 ley. The strata of red marl are in many places from ten to forty 

 feet in thickness, and on exposure to the air and frosts, decompose 

 into a red clay highly charged with iron, disclosing nodules of the 

 red oxide of iron in considerable quantities ; and occasionally fossil 

 shells of the genus Unio, completely changed into the same mate- 

 rial. From this fact, we are led to conclude, that these deposits 

 were made in fresh water, and probably in a calm and tranquil con- 

 dition, as the texture of the marl is very fine and smooth. Several* 

 shells, taken from the red marl, a few miles west of Marietta, are 

 figured on page No. 1 of the wood cuts, and numbered 17, 18, 19, 

 20 and 21. Below the surface of the earth, beds of the red marl 

 are found of much greater thickness. 



In boring for salt water, on march run, a few miles N. W. of Ma- 

 rietta, a stratum was recently passed, of one hundred and fifty feet, 

 resting on sandstone ; tracts of tolerably level land, several miles 

 in extent, are sometimes found near the heads of small streams. 

 In these situations, diluvium, or earth deposited from water of very 

 ancient date, forms the superstratum. It is composed of an ash col- 

 ored, tenacious clay above, and deep blue, or dark colored below, 

 resting on gravel or sand, in which is imbedded decayed wood ; de- 

 posits of this kind have been passed through in sinking wells, at the 

 depth of sixty or seventy feet. Marine and fresh water shells are 

 sometimes found in the sand, lying side by side, as the following 

 detail will more fully show. Six miles above the mouth of the 

 Muskingum and one mile and a half north of the Ohio river> a well 



