162 Stoux City Academy of Science and Letters. 
BUILDING STONE. 
The rocks of Dakota County are usually too soft to 
be suitable for building. Certain beds in the Dakota 
sandstone at Jackson and at Homer have been quarried 
for local use. Foundations and chimneys were formerly 
very frequently constructed of the stone, but now the 
cheapness of bricks from the Sioux City kilns has almost 
driven the sandstone into disuse. In the northern part 
of the county the slabby limestone of the Greenhorn 
member were likewise used to a small extent. 
LIME. 
At the base of the bluffs in the northern part of Da- 
kota County are the remains of several lime kilns. The 
Greenhorn chalks and limestones were there burned for 
lime in the early days, but the industry has been inactive 
for years owing to better grades of lime coming into the 
market from the east. 
SAND AND GRAVEL. 
Sand is abundant along Missouri River and beds of 
eravel are occasionally uncovered there. Pits of sand 
and gravel will doubtless be opened high in the escarp- 
ment above the Greenhorn limestone beds when the de- 
mand for such material warrants prospecting for it. 
