596 Wisconsin Academy of Sciences , Arts , and Letters. 
area can now readily be made, whereas a few years ago this 
would have been attended with very great difficulty and ex¬ 
pense. 
Occurrence of Iron Ores .—It has been said that geological sur¬ 
veys do not often discover iron ore bodies. This is true. What 
a geological survey can do is to map and limit the possible iron¬ 
bearing formations, and thus sharply outline the area which it 
is profitable to explore. It has been demonstrated beyond ques¬ 
tion that all of the iron ore deposits of the Lake Superior re¬ 
gion occur in a certain definite kind of formation, which can be 
accurately mapped where there is not too much surface cover - 
ing, by combining the study of the rock outcrops with the re¬ 
sults of magnetic surveys. The exact positions of the ore bod¬ 
ies within these areas can only be ascertained by prospecting. 
However, very definite rules have been formulated by the Lake 
Superior division of the United States geological survey for 
prospecting within the iron-bearing formations. As an illus¬ 
tration of what a survey may be expected to accomplish, it 
may be said that the part of the Gogebic range lying in Wis¬ 
consin was studied and accurately mapped by the late Prof. 
Boland D. Irving. His report and detailed maps, on the scale 
of 3.6 inches to the mile were published in 1879, five years be¬ 
fore the opening of the first mine. Thus far, every mine which 
has been discovered on this range in Wisconsin lies within this 
belt, about 1,000 feet wide, located by him. The value of 
this report as is well known was thoroughly recognized by 
prospectors during the time of opening up the Gogebic range, 
and very large sums of money were saved by confining pros¬ 
pecting within the possible productive area. 
Road Materials .—The importance of good roads has recently 
been strongly emphasized iu this state. A high authority has 
estimated the loss on account of bad roads for each state of the 
Union at millions of dollars per annum. An eminent foreign 
writer has said that only a new and rich country like the 
United States can afford bad roads and streets. The subject of 
road materials was scarcely touched by the first state survey. 
The sources and qualities of materials adapted for good and per- 
