Douglas Couch, age 9, of Portland, Oregon 

July, says Andy, is a very fine time to think of ice and Ice Ages  We might even fly far, far to the north and take a look at the tail end of the last Ice Age  In Greenland, Canada and Alaska there are vast sheets of ice and frozen snow called glaciers  These glaciers are carefully measured and some experts think they are shrinking  Muir glacier 3n Alaska moved back four miles in about 14 years  Other northern glaciers seam to be moving back just a few inches or a few fast a year 

A glacier may nestle in a valley or high in a cleft of the mountains like a frown river  It may spread out over a plain in a flat field of ice, Its ice may be many feet thick and some of the glaciers at the south pole are layers of ice two miles thick  Ice is very fragile, always ready to crack under stress and strain  For this reason, glacier is always moving 

The bulky layer of ice slides down a valley, flows down a mountain slope or spreads its edges cut over a plain  As a rule, it moves so slowly that it takes years to measure the changes  As its ice melts and runs away in chilly streams, more snow falls on the surface to become more ice, It may take thousands of years for a snowfall near the center of the glacier to reach the edges and turn into running water 

The size of the glacier may shrink or it may grow  This depends upon the climate, which is the weather through countless summers and winters  Suppose our climate changed so that the year‑round weather was just a little cooler  Winter would bring snow and more snow  The summer days, just above freezing, could not melt all the snow before winter came again to bring more, The snow on the ground would pile up deeper and deeper every year  It would freeze into a solid sheet of ice and become a glacier 

This is how the cruel Ice Ages began in the past, Glaciers formed, especially in the north, and each year grew bigger  Some were two miles thick  Their edges were steep walls of ice inching farther and farther south  They crushed over forests and hills  Boulders and rocks, gravel and soil sere frozen in the solid ice and pushed southward as the glaciers grew  The plant life perished and®r the cruel ice  Some of the animals moved south ahead of the glaciers  There was plenty of time to move, for it took many thousands of years for the glaciers to creep down over much of North America and Northern Europe,

A last the climate changed and summers became warm again, The winter’s snow melted and so, bit by bit, did the glaciers  But it took thousands of yea  i•s for them to shrink beak to the north  Boulders and gravel were dumped from the frozen glaciers as the ice melted, often far south of their homes  The pointed hills had been rounded and smoothed, rocks had been scratched by icy fingers and for a while the newly freed earth was wet and swampy,

There have been many Ice Ages in the past  Each one lasted many thousands of years and then came a long spell of warm weather  The glaciers of Canada, Alaska and Greenland are most likely the disappearing tails of the last Ice Age and we can expect a gentle climate for the next few thousand years  However, no one can promise this  For we do not know yet what causes the cruel Ice Age to come and go as they do