Altitude of the Blue Lime- 

 stone Formation at 



OSBORN, O. 



BY S. F. WOODARD, OSBORN, OHIO. 



In Vol. I, Chap. XIII, of the State Geological Keport, the Cin- 

 cinnati Grroup or "Blue Limestone" foi'xnation is treated oi. In that 

 chapter reference is made to the height of the top of said formation 

 above low water mark at Cincinnati at several points, which are indi- 

 cated on the map opposite page 413 in the volume mentioned. The 

 altitudes of said points are also given in a tabular statement on page 

 414 of the same volume. Comparing the altitude of said points, the 

 top of said formation is shown to decline four feet to the mile, going- 

 north along the arch of the Cincinnati Anticlinal. (See Vol. I, 

 pages 414 and 415). Therein, Station K, one mile above Osborn, is 

 given as having an altitude of 415 feet above low water mark at (Jin- 

 cinnati, whereas, it should have a height of 450 feet to be in harmony 

 with the altitude of the other points given. 



Station L, somewhat east but only about four miles south, has an 

 altitude given of 4(J(j feet, and Station F, a very little west and about 

 13 miles farther south, is given as having a height of 503 feet. De- 

 ducting four feet to the mile, in either case, leaves about 450 feet for 

 the height of Station K, instead of 415 feet as given in the survey. 



On page 414 of the same Report, Prof Orton attempts to account 

 for this discrepancy by supposing the whole outlier of the above 

 Clinton Limestone to be there depressed below its normal level ; but if 

 any one will take the pains to examine he will undoubtedly come to 

 the conclusion that the Professor has made a mistake in taking the 

 altitude of the top of the Blue Limestone formation at Station K 

 instead of there being a depression of the Clinton Limestone. For, 

 mark, in Volume Second of the Geological Survey Prof Orton him- 

 self, in his article on Greene county, page 662, gives the altitude of 

 Osborn as 410 feet above low water mark at Cincinnati. Now, running 

 up the railroad track one mile to Station K, the elevation of the track 



