p. 19

-19-

1827.

sided cells, resembling honeycomb, generally covered with the bituminous oil above mentioned. As respects the origin or cause of the honeycomb rock, contrary to the opinion of many persons with whom I have conversed on the subject, vix. that it is real honeycomb petrified, I suggest the idea those six-sided cells were formed by numerous small air bubbles, formed there when the rock was in a plastic state. This may be the visionary imagination of a boy, suffer it to be so, and should it be considered by you as absurd or incorrect, do correct it, or anything else you think proper; or in other words I have not seen it explained in a similar way by any author I have access to, although it may not be new. It is this rock which forms the rapids of the Ohio. The stratum descends towards the west, the edge of it projecting above the surrounding country, would form an obstruction to the river, which would continue to rise until it ran over at the lowest place and then regaining its former level it would form rapids.

Instead of continuing in its course it would run down in the direction in which the stratum descends; or at least it would tend that way and gradually adapt its course to it. A variety of this lime rock forms when calcined in the usual way, a cement, which has the property of getting very hard under water, hence the name water lime rock has been given to it. A thin layer of coarse grained lime rock, probably the Oolite or roestone lies immediately on it. It forms a small island opposite Shippingsport called Rock Island, and is quarried from the lock pit at the lower end of the canal. Its color is blush-gray; fracture conchoidal; adheres slightly to the tongue; emits an argillaceous odor when breathed upon; and it effervesces with acids. When calcined it is a buff color and does not slack with water like common lime but is ground for use in a steam mill erected for the purpose. It is used in the construction of the lock and other mason work in the canal.