588 C. WHITTLESEY ON THE PHYSICAL 



XVIII. The Physical Geology of Eastern Ohio. By Colonel Charles "Whittlesey. 



Read February 3, 1869. 



\V HILE engaged upon the Geological Survey of Ohio, under the late Professor W. W. 

 Mather, thirty years since, my duties were principally confined to the physical side of geol- 

 ogy. The survey was abruptly terminated in the spring of 1839, before a reconnoissance of 

 the State had been completed. No final report was made or called for. Two brief prelim- 

 inary reports, which are now rare, were published in pamphlet form. It was a part of Pro- 

 fessor Mather's plan, to determine not only the boundaries of the formations in a geological 

 sense, but to ascertain their exact dip, thickness, and mass, by topographical surveys and 

 levels. This part of the work was confided to me, constituting a department which has 

 never been thoroughly carried out in any of the State surveys. Our intention was to con- 

 struct for each county a correct map, with geological profiles which should be mathemat- 

 ically exact. 



The profiles would thus show all the irregularities in the thickness and dip of the strata 

 in the coal region, which embraces about one third of the State on the east. This is of the 

 highest practical importance, because the coal seams, and all the other beds of the coal series, 

 thin out, thicken up, or disappear, in short distances. They are not at all regular, like the 

 English series. Such detailed maps would have constituted a State Geological Atlas, based 

 upon actual surveys. 



Most of the information collected by me for this purpose was left in the office at Colum- 

 bus, and is now lost. My field-books were retained, and probably the other members of the 

 survey retained theirs ; but Professor Mather, Professor Locke, and Mr. Hildreth are dead. 

 Of the field geologists, only Professor Briggs, Colonel Foster, and myself survive. Professor 

 Rutland's Report on the Natural History of the State was more complete than the others ; 

 his department therefore suffered less by the unexpected termination of the survey, than 

 the departments of geology and mineralogy. In 1838, there had been surveys made along 

 the principal valleys north and south, on routes from Lake Erie to the Ohio, to determine 

 the feasibility of canals. The office of the Canal Commissioners, to whom the present 

 " Board of Public Works " are successors, then contained all the levels taken for canal pur- 

 poses. Since that time the State has been intersected by a great number of surveyed lines 

 for railways, crossing the canal surveys at all angles. This net-work of surveys gives with 

 reasonable accuracy the elevations of the principal summits, which I have preserved as far 

 as practicable, in the hope that the geological survey might be renewed, and that in addition 

 to correct profiles of the strata, there might be made an exact geological and topographical 

 model of the State. The railway surveys are not anywhere collected in one office. Many 

 of them are lost, or so dispersed among the papers of defunct corporations, that they are 

 inaccessible. Of late years, I. N. Pillsbury, Esq., of Cleveland, a well-known civil engineer, 

 has assisted me in collecting the profiles and surveys of railroads, and has recorded in 

 book form the elevations of the prominent points. In comparing levels on different lines, 

 we have found numerous discrepancies, in some cases amounting to (10) ten feet. They 

 arise from three sources. First : inaccuracies such as occur in all preliminary lines, to which 

 no subsequent corrections are applied. Second : in all surveys commencing at Lake Erie, 

 the water line for the moment is made zero ; and this is subject to a fluctuation of many 

 feet. The mean elevation of the surface of this lake is not determined precisely. I have 



