Column: Gravel is gold

Published 8:40 pm Friday, November 18, 2005

By Staff
One of the cornerstones of our nation's greatness is our abundant natural resources. We all appreciate a seemingly limitless supply of clean water and never ending source of timber. Oil and natural gas fuels our mighty industry, allows us to be mobile and keeps us warm. Vast deposits of metals and minerals from iron, lead and copper to the riches of gold and silver fulfill our every need. These are the things that come to mind when we think of natural resources. There is one unsung resource hero that few of us think about yet is one of the most important - gravel, plain old lowly gravel. Without gravel our roads and highways would be mud wallows. Concrete is next to useless without gravel. There would be no high rise buildings or even foundations for simple wood structures. We would be existing in single story adobe huts. Without gravel to filter and drain our sewage systems we would be wallowing in defecation.
I never thought much about gravel until we built our new house. Or, more precisely, when we paid the bill for the gravel that went into our drive, drain fields and sewage system. I had no idea gravel and gold are of equal market value. Being the curious type I was compelled to learn more about this stuff, not only why the big price tag but where all those neatly rounded little stones come from in the first place.
One of the first things I learned is that good gravel does not appear everywhere. Here in the upper Midwest we are fortunate to be in rich gravel country. In some other places of the world my bill would have been much higher yet. Gravel is the result of erosion of bedrock. In some cases this may come from weather factors such as freezing and thawing, wind and rain. Weather alone, however, is a pretty poor way to make gravel. More efficient is water flowing over bedrock, breaking it down and rounding the particles. This we often see in streams. A few streams here and there, though, are not about to satiate our glut for the millions of tons of gravel we use every year. Then there are the deleterious side effects of digging up our rivers like rerouting waterways, killing wildlife and all the other things we used to do before we knew better.
The real granddaddy of gravel production was the glaciers. As the glaciers inched their way across the land they broke up the surface of the bedrock. These pieces were drug along by the ice. As centuries turned into millenniums the constant movement of the glaciers ground the rocks smaller and smaller. Of course, some sloughed off the bottom of the glacier along the way, making small deposits of rather large rocks and gravel but these are quite useless for commercial purposes.
It's when the glaciers stopped and began to recede that gravel production really got cooking. Sometimes the gravel and its smaller brother, sand, were simply left in a flat blanket across the land. Other times the gravel and sand were caught in depressions and valleys. Most often, though, it was washed away in immense river systems of melting glacier water. This is the premium stuff gravel gurus cherish. The flowing water further smoothed and rounded the gravel. Of more importance, it did much of the sorting and sifting naturally. The larger, heavier stones fell out first. As the debris washed downstream it neatly settled out in graduated sizes. Eventually the melting subsided and the rivers dried up, leaving a deposit of gravel covered by lighter sand and other soils. The gravel people simply follow the deposit until the desired size is reached. Then all that's left to do is some minor things like settling land owner issues, removing up to several hundred yards of top soil, digging out the gravel, washing it, sifting it to precise size, storing it, loading it on trucks and such. With my new found knowledge I think I will quit whining about the cost and begin contemplating what would happen if we ran out of this most precious resource. Carpe diem.