Periodically, rocks buried in the soil at our farm will come to the surface. This is usually a very slow process aided by weather conditions. It can take years, decades, or in the case of huge boulders, centuries for the rocks to be pushed out of the dirt. After many years of mowing the fields and orchards, I have memorized the locations of all the rocks that jut from the surface enough to catch the mower blades. Or, at least I thought I had.
In recent years new rocks have lifted their heads within just a few winters. The piece of granite above is an example. It measures about 3.5 ft x 2 ft and for most of my lifetime at the farm has been nearly submerged. The stone is a piece from the cellar of a barn that stood on our property back in the 1800s. Until recently I have been able to mow right over this chunk of granite. Starting around four years ago, things changed. I hit the thing with my mower blade.
Trying to mow a rock with a rotary mowing machine is not recommended. I cringe whenever I hear that telltale ringing crunch of metal on stone. Luckily, it is a rare occurrence since removing the mower blades for sharpening is a tedious, time-consuming task. Yet, in the past few years I have caught several previously unknown rocks that have suddenly surfaced. What is so quickly moving these buried chunks of mountaintop or ledge? Most likely the power of ice.
Our weather here in central Maine has changed since I was young. Even in the last ten years there have been noticeable shifts in patterns, something I’ve discussed in prior posts. The current pattern involves much more rain in winter. Storms that once would have been pounding Nor-easter blizzards now deluge us in rain. The ground does not freeze as deeply as it once did so the water soaks in. Since it is still Maine in winter, a heavy rainstorm in December is often followed by several days of below-zero F temperatures. All that moisture runs down around and under the rocks in the ground and then freezes.
Freezing water expands with an irresistible power. The ice crystals push the rocks higher and higher until they break the surface. I believe the new warmth and excess rain are why rocks are appearing with such annoying regularity when I’m mowing. And also why older rocks are rapidly working their way more completely from the earth. As they pop to the surface, most of these stones can be loosened with the tractor bucket and moved out of the way. The great chunk of granite above will require some effort with chains, pry bars and the tractor to get it out of the middle of a hayfield. I’ll put that job on my To Do list.