PARTLY DISSECTED PLAINS IN JO DAVIESS COUNTY — 739 
THE GALENA PLAIN 
The Galena plain is best developed and distributed over widest 
areas and can be seen to best advantage in the district around the 
towns of Scales Mound, Apple River, Warren, and Stockton. 
Here is a surface 150 feet lower than the tops of the mounds and 
ridges of the Niagara plain, and 150-200 feet above the stream beds. 
Except for the elevations above it and the depressions below it, 
the plain forms a wide area of slight relief. In Section 8, Rush 
Township, where its surface has not been modified, it has a relief 
of less than 20 feet for a whole mile. This is a little more flat than 
the average, but not greatly so. This plain is practically confined 
to the northern two-thirds of the county; it does not appear to any 
appreciable extent in the southern one-third, and is lacking entirely 
along the south edge of the Galena and Elizabeth quadrangles. 
In the vicinity of Galena it appears in flattish or rounded divides 
midway between the upland mounds and the valley bottoms. By 
close observation, similar features may be seen about as far south 
as the Great Western tunnel in the Galena quadrangle, and to about 
the latitude of Stockton in the Elizabeth quadrangle. If recon- 
structed, this plain also would slope southward at a low angle. 
Stratigraphically, the Galena plain is located on the hard Galena 
dolomite or only slightly above it in the Maquoketa shale. The 
broad flat in the district around Scales Mound, Apple River, War- 
ren, and Stockton is underlain directly by the upper thin beds of 
Galena, or locally far from the main streams by 5—15 feet of Maquo- 
keta shale above the Galena. The rounded divides and narrow 
flats around Galena and north and south of that place are underlain 
by Maquoketa shale of thicknesses up to 30 feet. In the south 
part of the county where the Galena dolomite dips beneath the 
surface, the flat cannot be seen. 
In the case of the Galena plain, only three of the four above- 
discussed means of origin are possible. It cannot be an original 
marine plain of deposition, because the mounds and ridges of 
Niagara dolomite stand above it, and have been made by processes 
of degradation since the recession of the sea. It may, however, be 
a structural plain on the hard Galena dolomite, or it may represent 
the beginnings of a true peneplain, or perhaps it is conceivable that 
it was carved out from the shale and dolomite above the Galena 
