Gold and Other Minerals in lozca. — Calvin. 367 
ures in the region between Des Moines and the northeast cor- 
ner of the state. '^' Explorations for coal in the Mississippian, 
Devonian, Sihirian, or older systems of rocks are foredoomed 
to failure for the simple reason that these rocks were all com- 
pleted before a single workable coal seam was deposited, some 
of them before a single coal plant, or any terrestrial forms of 
vegetation from which coal might be formed, had come into 
existence. These formations all lie geologically below the 
coal. If one could begin in the Mississippian or lower forma- 
tions underneath Des Moines or in that vicinity, and bore up- 
wards he might have some chance of striking coal. Ikit boring 
downwards in any of the formations referred to, whether un- 
der Des Moines or at jjoints where the older beds come to the 
surface in the eastern part of the state, is going in the wrong 
direction; and the farther the l)oring is carried, the more hope- 
less, becomes the search. There is positively no coal in any 
parts of Iowa, which have formations older than the Des 
Moines shales and sandstones as the surface rock. The find- 
ing of coal is not a question of deep drill holes, Init is one of 
intelligent and thorough prospecting of geological deposits of 
a particular age. If the operation is l)egun in any formation 
older than the Des Moines, the drill may go through to Aus- 
tralia or anywhere else without finding a speck of coal. 
Petroleum and natural gas are like coal in one particular — 
they are derived from organic products. They are known to 
have their origin in dark bituminous shale, in limestones, which 
are in general of organic origin, in (|uantities of vcgetal)le mat- 
ter included in sanilstones, in remains of forests buried in the 
drift, in anv accumulations of organic matter which have un- 
dergone or are undergoing decay wliilc liermelically sealed 
from the atmosphere. 1lie marsh gas, which is ammally pro- 
duced bv the decay of vegetation at the bottom of j^onds, af- 
fords an illustration of the origin of one of the ])roducts we are 
considering, familiar to almost every observant person. Tt 
need scarcely be said, therefore, that rocks which are older llian 
•The Greenwood Park well at Des Moines has penetrated to the Cambrian 
and has put to actual test the statements which any competent pcologist 
would have made in advance. All the broad details of that borinj; could have 
been written out beforehand. The full record of the well, to the minutest de- 
tails, is given in Norton's Artesinn Wells of lown, Iowa Geol. Sur.. Vol. VI, p. 
294 et sell Scores of other deep wells scattered throughout Iowa and confirm 
ins all that would be inferred from studies of the siipcrficial exposures, are de 
scribed in the same volume. 
