Notice of Geological Surveys. 129 



one locality, and then in another it would be in an opposite direc- 

 tion. By examining " the several formations on a large scale, 

 the dip becomes very evident ; and as one formation sinks gradu- 

 ally below the surface and another superior one presents itself, it 

 gives rise to those important changes in the face and productions 

 of the country which we should hardly attribute to a slope so 

 moderate as one inch in a rod.^^ 



In connexion with Dr. Owen, geologist of Indiana, Dr. Locke 

 found that near the boundary of the two states, there is a summit 

 level and an anticlinal axis from which the strata dip in opposite 

 directions— east ward ly in Ohio, and westwardly in Indiana — so 

 that the " cliff limestone, which shows itself not many miles 

 east and west of Richmond, Indiana, descends and comes to the 

 bed of the Ohio river at the east side of Adams county, Ohio, 

 and at the falls of the Ohio, at Louisville, Ky." "The outcrop- 

 ping edges of the strata, therefore, present themselves at the sur- 

 face in the same order in the two states." 



The " blue limestone region," is covered by the rock called the 

 " blue litnestone,''^ which is the lowest rock that has been pene- 

 trated in this region. With its alternate layers of marl and mar- 

 lite, it is the exclusive rock even to the tops of the hills from 

 West Union in Adams county, to Madison in Indiana, and from 

 Dayton in Montgomery county, and Eaton, Preble county, Ohio, 

 on the north, to a line forty or fifty miles up the Licking river, 

 in Kentucky. At these places, or near them, the " cliff lime- 

 stone''' caps the hills ; while the blue limestone is found in the 

 beds of the streams, extending in some instances twenty miles 

 farther, and passes under all of the other strata. 



This extensive region is a table land five hundred feet above 

 the low water mark of the Ohio. Its valleys and the channels 

 of the streams are " sometimes bounded closely by abrupt banks, 

 or widening to half a mile or even four miles, present a rich ara- 

 ble alluvion or bottom lands." Where the marl is abundant and 

 becomes removed by the action of the weather, the layers of rock 

 (broken into irregular fragments) are undermined and slide down 

 with the earth, and are never left standing out in cliffs ; hence 

 the banks and hills are usually rounded. 



" The soil has been formed mostly from rocks and marl, iden- 

 tical with those which now lie beneath it, except where it has 

 been brought and deposited by waters, and does not contain at 



Vol. XL, No. 1.— Oct.-Dec. 1840. 17 



