68 Notice of the Louisville Canal, fyc. 



banks of the river below Shippingsport, but whether it rises 

 again I do not know. It contains a great variety of petri- 

 factions. The minerals which I have collected from it, are 

 few and common ; the principal are quartz crystals, calc- 

 spar, and sulphuret of iron. Several springs issue through 

 it, most of which contain a considerable quantity of oxide of 

 iron, held in solution by means of carbonic acid. This has 

 induced many persons to ascribe valuable medical proper- 

 ties to these springs. 



When newly exposed to the air, this rock continually gives 

 out an agreeable bituminous odor, occasioned by petroleum 

 or Seneca oil, which is found filling the cavities. In some 

 rare and small places, this rock is composed of small sixsided 

 cells, resembling honey comb, generally covered with the bi- 

 tuminous oil above mentioned.* 



It is this rock which forms the rapids of the Ohio. The 

 stratum descends towards the west ; the edge of it project- 

 ing above the surrounding country would form an obstruc- 

 tion to the river, which would continue to rise, until it ran 

 over at the lowest place, and then in regaining its former 

 level it would form a rapid. Instead of continuing in its 

 course, south west, 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 limerock forms, when calcined in the 

 usual way, a cement, which has the property of setting very 

 hard under water ; hence the name water limerock has been 

 given to it. A thin layer of a coarse grained limerock, prob- 

 ably oolite or roestone, lies immediately on it. It forms a 

 small island opposite to Shippingsport, called Rock island, and 

 is quarried from the lock pits at the lower end of the canal. 

 Its color is bluish-grey ; fracture conchoidal ; adheres slight- 

 ly to the tongue ; emits an argillaceous odor when breathed 

 upon ; and it effervesces with acids. When calcined, it is of 

 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 locks and oth- 

 er mason work on the canal. 



* Mr. Lapham very properly objects to the popular impression, that this rock 

 contains petrified honey comb ; these imbedded masses are evidently the variety 

 of madrepore, called by Mr. Say, (see Vol. 1 of this Journal, page 384) Favosite ; 

 productions as truly marine as any that are now formed in the existing oceans.— 

 Ed. 



