ANNUAL REPORT-ROAD MATERIALS. 
5a 
the sand is compact and hard. Thus the sand roads and 
the clayed roads supplement each other. 
The road-making clays are of a red or yellowish color, 
indicating a high percentage of iron compounds which 
probably assist in the bonding power of the material. In 
texture the clay is rather coarse, and breaks up readily. 
Bog Iron Ore. 
Bog iron ore occurs in various parts of the State, but 
usually in thin deposits and of local extent. It has been 
stated by Shaler, (U. S. Geological Survey, 15th Ann. 
Kept., p. 272, 1895), that where the surface of a lime¬ 
stone road can be covered with iron ore, the firmness of 
the mass is much increased. An iron oxide, such as bog 
iron ore, serves as a cementing material, and this is doubt¬ 
less the explanation of its usefulness for this purpose. 
Phosphatic Rock. 
Phosphate of a too low grade or too high in objection¬ 
able impurities to work commercially may serve in some 
localities as a useful road rock. The hard rock phosphate 
is harder than limestone and is reported to have better 
cementing qualities. 
