The School of Hard Rocks

Locally Grown

The School of Hard Rocks

OUR FARM HAS A LOT OF ROCKS— more than its fair share, I would say. The last glacier that receded some 15,000 years ago was particularly generous to us. Both during its advance and retreat, this sheet of ice a few thousand feet thick, deposited a hodgepodge of solid material, often referred to as glacial till. The many different rocks and their grindings have shaped our landscape and soils in the most profound ways. They are the foundation from which all else springs.

The rocks are both a burden and a boon to us. They are hard on our equipment and sometimes our bodies. They wear down and occasionally break the steel tines of our cultivators, the shears of our plows, and the blades of our hoes and rototillers. The sharp little ones penetrate the soft spots of our knees when we kneel down to harvest herbs or weed carrots. Medium-sized rocks—from a goose egg to a football in girth—obstruct our planting and have to be removed by hand. Larger rocks can be extracted only with a tractor or backhoe. Still others are so big that they literally block our passage, requiring us to work around them. They are like islands in the middle of fields. Then there is the bedrock itself, in the form of a jagged ridge along the southern border of the farm. This wooded high ground is a conspicuous extension of the earth’s continental crust.


Every year we spend many hours clearing rocks from our fields. We call this rock-picking. Someone—usually me—sits on a tractor with a bucket and drives slowly back and forth. At the same time, a couple of less fortunate individuals scurry about in front and on either side of the tractor. Their job is to pick up all the medium-sized rocks (there are too many small ones to worry about) and throw them into the bucket. The tractor keeps moving and so do the pickers.

Our larger tractor bucket can hold somewhere between 1,000 and 1,500 pounds of rocks at a time, by my estimate. No one has kept count, but, over the past 20-odd years, we must have picked at least a thousand buckets of rocks. At the conservative end of the estimate that would be 500 tons. The thing is, there seems to be just as many rocks in the fields as there were before we embarked upon this Sisyphusean undertaking. I’ve come to accept this, but go on picking them anyway.

Over millennia, rain and wind and freeze and thaw wear down the earth’s rocks, transforming their minerals into particles of soil. 

The truth is, I’ve grown fond of the rocks. To me, they exemplify stability and staying power in a mutable and uncertain world, too much in the thrall of my own species. No two rocks are quite alike; each has its own presence, its own shape, size, hue, heft and composition. Each has a past that reaches back far beyond human time. And almost every rock has a history of being jostled around, battered about and exposed to the dynamic forces of the earth. Even so, rocks en dure—perhaps not forever, but for a lot longer than we do.

Over millennia, rain and wind and freeze and thaw wear down the earth’s rocks, transforming their minerals into particles of soil. Forty percent of a typical fertile soil is made up of small pieces of rock and minerals. The rest is air (25 percent); water (25 percent); and organic matter, which comes from decomposed plant and animal material (5 percent). We need our rocks; they are a part of us.

Before the invention of barbed wire, flat rocks of suitable size were used to build stonewalls to contain livestock. Some of these impressive walls still stand in the woods of our farm, as solid as they ever were. Today, we are more dismissive of our rocks—many that are taken from the fields are dumped along hedgerows; some are used to fill potholes in the driveway, others to weight down weed barrier, row cover, or mesh fencing. Sometimes an elongated rock is used like a hammer, to drive a stake into the ground. Or, three or four flat rocks are stacked on top of each other to form a cairn or marker, indicating where we have ended a planting, or switched from one variety of vegetable to another. We’ve used rocks to build retaining walls and construct bridges across wet areas that a tractor might sink into. And, every now and then, we use an especially fine rock as a tombstone to remember a favorite canine or feline friend. I sometimes hear myself complaining about all the rocks we have to contend with but, sooner or later, I’m looking for a special one to put to good use.

I’ve heard old farmers in our area talk of families of rocks, which implies that rocks can appear and apparently multiply in patches of soil that have been relatively free of them. There are a couple of reasons for this. Deep tillage with a moldboard or chisel plow brings buried rocks to the surface. Another, less obvious, reason is climactic: The winter freeze-and-thaw cycles cause water in the soil to expand and contract. Rocks as big as cars can get moved around, usually upward. Old timers used their knowledge of freeze and thaw to split rocks so they could be more easily moved: They drilled holes in large rocks they wanted to be rid of and poured water into them before cold weather set in. The freezing water expanded and split the rocks into more manageable pieces. It’s something nature has been doing, albeit without drill bits, for a very long time.

Not long ago, during a tour of the farm, a friend remarked: “It’s too bad you can’t sell rocks.” I agreed, feeling slightly offended, but then told her that in a sense we do. Without all the rocks and the minerals they yield up, our vegetables wouldn’t be what they are. Besides, I told her, the rocks have much to teach us.

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