SEDIMENTARY ROCKS OF OHIO 85 



The northern line of wells. — At Findlay the interval between the 

 crystalline rocks and the top of the Trenton formation is 1,605 f^^t. 

 This will be considered as constant for northern Ohio. 



At Lorain, the interval between the Clinton and the Trenton 

 is 1,075 feet, at Cleveland 1,658 feet, an increase of 21 feet per mile 

 to the eastward. If this continues to the state line sixty miles 

 eastward, the interval would be 2,918 feet (1,658+1,260). 



In Wayne Township, Ashtabula Coimty, the Clinton formation 

 is found 2,940 feet below sea level. Data from wells at Lorain, 

 Avon, East Cleveland, Chester Township, Geauga County, Harts- 

 grove and Wayne townships, Ashtabula County, show an average, 

 although not constant, decline of the surface of this formation of 

 22.7 feet per mile. If the eastward decline continues at the same 

 rate to the state line, the surface of the formation should be about 

 3,172 feet below sea level at this point. Add to this figure the 

 estimated distance between the top of the Clinton and the top 

 of the Trenton, 2,918 feet, and the distance from the top of the 

 Trenton to the crystalline rocks, 1,605 f^^t, and we have a total of 

 7,695 feet, the depth below sea level at which crystalline rocks 

 should be found near the northeastern corner of Ohio. An addition 

 of at least 1,000 feet should be made for the thickness of strata 

 above sea level, giving a total estimate of some 8,700 feet of sedi- 

 mentary rocks in this part of the state. 



Central Ohio. — The wells extending from Columbus to north 

 central Muskingum County are not on a straight line, but the 

 departures to the north side are practically balanced by those to 

 the south. It will be seen later that the variation in thickness of 

 the sedimentary rocks along a north and south line is comparatively 

 slight in short distances. 



The Clinton occurs 186 feet below sea level in a well along the 

 Mifflin Township line in the eastern part of the city of Columbus. 

 From this well to one at Basil, the top of the Clinton declines at an 

 average rate of 41 feet per mile. Eight other wells, some of them 

 as far east as north central Muskingum County, show a decline 

 ranging from 56 feet to 34 .9 feet per mile, with an average of 46 .6 

 feet. Using the last figure, the top of the Clinton should be 5,778 

 feet (= 186 -F 5,592) below sea level at Wheeling, 120 miles eastward. 



