lOWA ACADEMY OF SCIENCE 
13 
Iowa, in reliable form, a fund of useful information that should prove of the 
highest value in the further development of this important industry. 
The lead and zinc resources of the state have received deserved attention. 
Early in the history of the present Survey a full report on the mining industry 
around Dubuque was prepared by Leonard on the basis of extended investiga- 
tions made in the field, and was published in volume VI. Later, the subject 
was reinvestigated, and in greater detail, by Bain, and the results of this later 
work constitute the greater and the more important part of the report on the 
Geology of Dubuque county, which appears in volume X. 
The oldest of the rock formations native to Iowa, and the only deposit of 
pre-Cambrian age in the state, is the Sioux quartzite. This is limited to a 
small area in the extreme northwest corner . of Lyon county, but it is quite 
extensively developed northward and westward in Minnesota and South Dakota. 
This unique formation was deemed worthy of a special report, vs^hich, after 
careful field study, was prepared by Dr. Beyer. 
In spite of all that can be said and done, there are people in enlightened 
Iowa who persist in the erroneous notion that it is necessary only to bore deep 
enough to get supplies of petroleum and natural gas in any desired quantities 
in any locality. Many thousands of dollars have been uselessly expended in 
the search for these products in regions that had previously been explored 
with the drill in efforts to get supplies of water. The records of these drill 
holes were available, but the parties interested seem to have been possessed, or 
obsessed, by the curious notion that wells drilled through the geological forma- 
tions to get water prove nothing as to the presence of gas or oil. When you 
want water, drill for water; and when you want gas or oil, drill for gas or oil; 
as if the intent of the driller exercised some mysterious influence on the nature 
of the products to be obtained from the deeper-lying strata. The Survey has 
told the people the truth in all such cases and has conscientiously tried to get 
them to see it, but the truth has proved in most instances to be exceedingly 
unwelcome. Some have tried to ward off the unwelcome facts and compel the 
rocks of Iowa to yield products they do not possess by indulging in coarse abuse 
of the Survey and its officers, but the result has not been a pronounced success. 
The position of the Survey has been sustained in every case; it has nothing to 
apologize for, nothing to recant; it may be worthy of note, though in no way 
unexpected, that the loudest and coarsest of the vilifiers have never offered a 
single word of manly apology. The small amounts of gas from deposits of 
sand and gravel in the drift have been recognized since before the Survey began, 
and it is hoped that many more of these reservoirs may be found. Letts and 
Herndon are the best known localities .i^mong those where Pleistocene gas is 
known to exist. The deep wells, so widely distributed, have in general settled 
the question of oil or gas from the older geological horizons, but there yet 
remain a few unexplored areas that may some time surprise us by becoming 
productive. 
The work of the Survey is now far enough advanced to make it possible to 
construct a detailed section of the rocks of Iowa, fairly correct. Thin zonesr 
of economic or scientific importance have been determined and recognized, in 
some instances over hundred of square miles. For example, the non-mag- 
nesian, lithographic limestone which is the principal basis of the Portland 
cement industry at Mason City, has been traced from Iowa City to Howard and 
Mitchell counties and across the line into Minnesota. A reef of stromatoporoid 
