A thousand years ago, the proud peaks of the Rockies looked just as they do today, There has been no noticeable change in the forested slopes of the beautiful Appalachians in the past million years. But all mountains have a beginning and an end, though their life span is so long that they change hardly at all in ten or even twenty human life times.

Suppose we could see our planet as it was 500 million years ago. There were no western mountains in North America and no Appalachians down its eastern shores. In this remote past, the Laurentians of eastern Canada were lofty peaks. Long ages of wind and weathering have worn these ancient mountains down to gently sloping hills.

A mountain range has an old age lasting millions of years during which its proud peaks are worn down to level ground. It also has a youth lasting millions of years during which it grows from a ditch, called a geosynline, to its loftiest height. To the geologist, this dramatic life story is part of diastrophism   the slow and persistent heaving and dipping, bending and buckling of the earth's crust.

A geosyncline is a long and shallow ditch collecting the drainage from countless muddy streams. Through the ages, its floor piles deep with silt and debris and in time, the weight of these extra lagers upsets the balance of the earth's crust. This, say the geologists, is what happened in New England some 300 million years ago, About 100 million years later, it happened to a geosyncline lying to the south of New England.

Slowly, slowly, the crust of the earth bent up in a gigantic wrinkle. First the northern, then the southern arm of the Appalachians poked up their heads and continued to grow taller and taller until the balance of weight in the earth’s crust was restored. This diastrophism is mountain making.

Meantime, other forces were at war with the growing mountains. Rainfall and gushing streams, blustering winds and perhaps icy fingered glaciers tore at the growing peaks and washed surface debris down the slopes. But young mountains grow faster than the warring weather can tear them down. When at last the growth is finished, the battle turns. Through millions of years of old age, the mountains are worn down again to the level ground.

 Geologists are now looking for deep reasons to explain the diastrophism in the earth's crust. They suggest that these surface ups and downs may be caused by the mantle layer which begins 30 to 40 miles below ground. There are a lot of facts to support this theory, but we need to know more about the deeply buried mantle layer before we can prove it.