IGY IN RETROSPECT—ROBERTS 281 
oceans is substantially larger than formerly thought—still another 
factor in the heat-engine cycle. Perhaps the most immediately inter- 
esting of the ocean-floor discoveries was a scattering of iron and man- 
ganese nodules, mixed with nickel, cobalt, and copper, over millions of 
square miles of the southeast Pacific, in concentrations worth hundreds 
of thousands of dollars per square mile. The economics of dredging 
appears promising. 
Glaciology.—Like a smaller and less mobile counterpart of the sea, 
the ice deposits of the world store, and eventually release, water and 
thermal energy. Thus, they contribute their part to the endless cycle 
of weather and ocean phenomena. They also constitute valuable rec- 
ords of the past. 
The ice in Antarctica is 40 percent greater than formerly believed 
but is now diminishing. It averages 10,000 feet in depth and con- 
tains 90 percent of all the ice in the world, some 614 million cubic 
miles. In many places on the high icy plateaus, 10,000 feet and more 
above the sea, the ice has been found by seismic prospecting methods 
to rest on underlying earth thousands of feet below sea level. Such 
discoveries show that we may have there a great archipelago in- 
stead of a single land; however, the IGY seismic explorations indi- 
cate a crustal structure of continental type. Perhaps it is a “foun- 
dered continent.” It seems likely that removal of the ice would 
disclose a broad strait between the Weddell and the Ross Seas, cutting 
Antarctica into two major land masses. 
Ice borings in Greenland and Antarctica have reached layers 
formed by the precipitation of more than a thousand years ago. 
These layers can be read like tree rings, and the thermal insulation 
is so good as to have preserved the temperatures of past centuries. 
Ancient climates are thus known, and clues to the future may be 
deducted. This is one of the ways in which we know of warming 
trends of world climates. 
We know, through observation of precipitation rates, that the 
Arctic has twice the snowfall of Antarctica. Pollen traces in perfect 
preservation and ash deposits at certain levels attest the atmospheric 
impurities of former times, and may give clues to ancient volcanic 
activity. 
Glaciological studies of the great ice caps and smaller glaciers 
throughout the world provided first steps toward an understanding 
of the regimen, behavior, and physical properties of the great volumes 
of water withheld by climatic conditions from free circulation. An 
understanding of heat balances and interface reactions was gained. 
It was learned that glacier behavior throughout the world is syn- 
chronous—recession is going on everywhere. Incidental results were 
the creation of a corps of world scientists willing and able to endure 
the rigors of polar work and life, and in Antarctica, at least, a 
