412 } GEOLOGY OF OHIO. 
reports of the Survey. The latter is deubtless of much more frequent 
occurrence. It is to a wide-spread stratum of interglacial vegetation that 
the buried tree-tops, roots, leaves, and ancient soil, so often reported in. 
the digging of wells and other like excavations, must be referred. 
The Forest-Bed, as this stratum has been designated, is of much less 
frequent occurrence in Preble county than in the counties to the south 
and east of it, but there are still many evidences of its presence within 
this area. In Harrison township a tree top is reported to have been 
struck at a depth of thirty feet. | 
An ochre seam, which, it will be remembered, sometimes accompanies 
the Forest Bed and sometimes replaces it in the regions to the south- 
ward, is also occasionally met. with in Preble county. It is generally 
found associated with a gravel seam, which it cements into a hard-pan, 
which must be penetrated in order to reach the water veins. 
The beds of modified Drift, as the sand, gravel, and clay that overlie 
the bowlder clay in stratified deposits are called, occur abundantly in © 
the county, not being confined to the deeper valleys, but being found as 
well over most of the uplands of the county. In the northern town- 
ships, and especially in the flat-lying districts, they have a general 
thickness of about twenty feet, of which the following may be taken as 
a representative section : 
tort ua Seen NN NNRE aL Rh MMA MME RIEL OLE mami Leen aes se 
Welllowrclayistrealkedmwathybluishy Cl avaeme seeleeets tel ea nerin enero 10 
Blue clay (sometimes brown), always fine-grained, and free from gravel.-.. 8 
Underneath are found the seams of sand and gravel that cover the | 
bowlder clay, and which constitute the water-bearer of much of this 
region. | 
In all of the above named particulars the Drift of Preble county is 
seen to be part and parcel of the great Drift field of Ohio, but there is a 
single feature that remains to be mentioned in which it has preéminence 
over all contiguous areas. A very remarkable bowlder belt traverses its 
central and eastern regions—more remarkable than any similar belt 
thus far reported in the State. There are various points in this general 
region where bowlders are very thickly strewn over the surface for 
limited areas, as, for instance, along the uplands that bound the Great 
Miami Valley for twenty-five miles above Dayton, on the west side of 
the valley, directly opposite Dayton, and also in the country that lies 
west of the Stillwater, in the vicinity of Union, Montgomery county, 
but none of these bowlder belts attain the proportions of that now under 
consideration. _ 
Its northern boundary is not very distinctly defined, but there is a 
