STATE GEOLOGIST, 103 
Strangely enough, the opinions of men who are obviously crude and 
ignorant, and whose opinions would carry no weight in any other con- 
nection, are often taken in establishing mineral industries, on the basis of 
their practical experience, while that of trained experts is condemned a 
theoretical. Even the word of interested persons, not possessing a rudi- 
mentary knowledge of technical matters, is readily believed by otherwise 
well-balanced conservative business men. ‘The American habit of “boom- 
ing” towns and localities has had a great deal to do with this reckless 
kind of work. 
In looking for a suitable clay material the experienced prospector 
makes use of all natural and artificial excavations, such as gullies, river 
banks, railroad cuts and quarries,‘ for determining the character of the 
rocks in a certain locality. He watches every clay outcrop, and by 
applying the rudiments of geological knowledge is usually able to trace 
down the available clay beds. With the help of the geological reports 
and maps, and especially with the assistance of the excellent topographical 
survey maps of the U. S. Geological Survey, the method of the attack is 
easily outlined. 
If a random sample of a clay outcrop has shown a satisfactory com- 
position and is promising in regard to its physical characteristics, an 
opening should be made into it, removing the surface clay, and a sample 
taken from the material within the bank. If this should likewise prove 
satisfactory, the bed is attacked at several places, examined, and finally 
a survey is made of a tract which affords enough material for the 
capacity of the factory which it is intended to erect. The area of the 
land is plotted and a topographical survey made. Now the map is 
divided into squares whose sides should range between 50 and 100 feet 
in length, depending on the different thicknesses of the deposit. If the 
latter is thick, say 30 or 40 or more feet, the square should be taken with 
sides of about 50 feet in length; if it is but several feet deep, they 
should be too feet, since the area to be examined in this case is so 
much larger. At the center of every square a test hole is sunk and the 
material brought up by the drill put aside for analysis. If at the depth 
drilled the clay is apparently of the same structure, color and general 
appearance, a sample need only be collected for every ten feet of depth; 
if, however, on drilling, various materials are found, a sample must be set 
aside for each different material. 
By means of these drill holes sections can be plotted cutting the 
center of the area at right angles, one section passing’ through the 
deposit, say from east to west, and the other from north to south. After 
having plotted these sections to scale on a map the total amount of the 
different kinds of clay available, in cubic feet or cubic yards, can then 
be calculated with sufficient accuracy. 
It is hardly necessary to state that the samples must be kept in 
suitable, tight receptacles, carefully labeled. 
