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IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
seas and at considerable altitudes above sea level has led to much 
speculation. The Greek and Roman scholars are positive in their 
opinion that these record the former .presence of the sea — a con- 
clusion which might well have been accepted by their successors 
of the Middle Ages and later. How such changes of level were 
effected they could not explain, any more than they could tell 
how the mountains and the valleys, the rivers and the plains 
attained their present forms. Indeed it was not until the last 
pentury that the true explanation for these features was found 
— again, the most reasonable and natural explanation, lying 
ready to hand when some observer should be clear minded 
enough to grasp it. But before the fall of the Roman empire 
the operation of certain well defined natural laws had been ap- 
preciated and it is noteworthy that the development of the scien- 
tific spirit in investigating Nature was unhindered by theological 
preconceptions or popular misconceptions. If the same tolerance 
had been manifest in Christian Europe the history of scientific 
research would have been far different than it actually has 
been. 
During the Middle Ages the Arabs endeavored to enlarge the 
bounds of natural science and one of them, Avicenna (980-1037), 
states with admirable clearness that “Mountains may arise from 
two causes, either from uplifting of the ground, such as takes 
place in earthquakes, or from the effect of running water and 
wind.” 
By the time of the revival of learning the Church had ob- 
tained such a hold on the minds of men and on their methods 
of study that they were allowed to express no opinion on the 
age of the earth or its geologic history which was counter to 
the words of the first chapter of Genesis. This effectively dis- 
posed of the notion that the sea had once overspread the lands 
and that in it had lived animals whose remains are now entombed 
in the rocks. For had not the Creator separated land and sea 
before animal life was called into being? Neither was there any 
place for the heresy that the fossiliferous rocks, though perhaps 
several thousand feet thick, had accumulated during immense 
periods, for there was no escaping the dogma that the world had 
been created out of nothing about 6,000 years ago. 
So to escape martyrdom and the irrefutable facts of Nature 
at the same time there was adopted the expedient that these 
