396 SEOLOGY OF OHIO. 



tree, standing erect, with the trunk and some of the branches almost entire. This tree 

 continued down to a depth of thirty feet, where he found its roots, in the natural posi- 

 tion of growth, peuetratinj; the hard-pan." 



The remarkable example noted in the second edition of the Report of 

 the Ohio Geological Survey for 1869, in the chapter on Montgomery 

 county, will be recalled. (See also Silliman's Journal for July, 1870.) 

 A peat bed, fourteen feet in fchicknesp, was found buried under one hun- 

 dred feet of drift deposits, itself overlying gravel and clay. 



2. The yellow, gravelly clay that makes the main element of the 

 Drift in all of this region is also very abundant in Butler county. It is 

 not formed from the weathering of the upper portions of the bowlder 

 clay in situ. The action of the atmosphere upon an exposed bed of blue 

 clay changes its color and also its texture, it is true, but much more than 

 this is required to account for the surface clays of Southern Ohio. They 

 have been worn away from their old places of deposit by water, and have 

 been re-deposited. The bowlder clay is always unstratified ; the yellow 

 clays are generally distinctly stratified. The uplands of the county, 

 especially of its northern and central portions, are almost universally 

 covered with deposits of this kind. There are no elevations in the 

 county that escape the deposits of the modified drift. 



The sand and gravel that make a third element in the Drift of this 

 region do not deserve a place by themselves. They form a phase only of 

 the second order of deposits, and must be referred not only to the same 

 general line of agencies, but also approximately to the same time. As 

 has just been stated, the highest elevations in the county give clear 

 proof of having been involved in the submergence, by which alone these 

 facts can be explained. Bowlders are found at all altitudes, and some of 

 the largest size are found at the greatest elevation. One lying on the 

 highest land of the west side of Ross township measured one hundred 

 and thirty cubic feet above ground. 



In concluding this description of the Drift formations of the county, 

 the opportunity may be taken to say that the history involved is a long 

 and complicated one. There can be no doubt that the general order of 

 events has been correctly determined in the best statements that have 

 thus far been made in regard to North American Drift; but the details of 

 the history are yet to be worked out. Oscillations of temperature and 

 level will doubtless be found to have taken part in the history, and the 

 time occupied in these changes will stretch into long cycles. 



In a description of the Drift of the county, the deposits of the Great 

 Miami valley require a place by themselves. The map accompanying 



