124 CARBONIFEROUS LIMESTONES 
wedge-shaped interpolation is well seen at the next section, a little higher up 
on the Des Moines, above Bald Point, where two thin seams of coal are seen 
tapering away until they finally run out as ae approach each other. (See Section 
No. 60, D.) 
MARL AND DRIFT RESTING ON CARBONIFEROUS STRATA, DES MOINES. 
f 
At a westerly bend of the Des Moines, here represented, designated on the chart 
of the river, “ Bald Point,” the hills are about two hundred feet high; laminated 
sandstone forms their base, while the main body of the hill is composed of ash- 
coloured, marly earth and drift. One mile above Bald Point, ledges of reddish 
limestone extend to the height of five or six feet above the water-level; and half a 
ile further, or about eight miles above the Rapids, fragments of ironstone are 
scattered on the shore near the water-level, mixed with a conglomerate of gravel 
and sand, cemented by oxide of iron. A few hundred yards above this place, on 
the left bank of the Des Moines, below the mouth of Honey Creek, ledges of soft 
sandstones project from under the drift. Interposed between the beds is a wedge- 
shaped siliceo-calcareous rock, which projects beyond the sandstones. 
The blacksmiths of Boone County have obtained some coal from a bed situated 
on Section 5, Township 83 north, Range 26 west. From one to two miles above 
the line between Townships 83 and 84, in latitude 42° 2’, alternating beds of sand- 
stone occur, overlying shale and coal; and two to three miles higher two seams of 
coal are seen above the water, one eighteen inches, and the other ten inches thick. 
They are associated with shales, and shaly sandstones. Nodules of ironstone are 
disseminated in the argillaceous beds below the eighteen-inch seam of coal. The 
lowest bed, which decomposes into a fine, light-coloured potters’ clay, gives out, when 
applied to the tongue, a strong astringent taste. 
About three hundred yards up the river, in nearly a northerly course, the lower 
bed of coal is at the water-level, but rises again, in conformity to the undulating 
depressions and elevations of the strata prevalent through this region. The beds 
thus attain an elevation of twenty to twenty-five feet above the water- 
