Mystery of the Bow in the Wall

A long-time customer called to ask if I’d take a look at a dry stone wall I’d built for him many years ago.  He was concerned that a woodchuck had taken up residence nearby and that its excavations had undermined the wall.  Upon inspection, I could see that the critter’s digging hadn’t compromised the structure, but a section of the wall did have a decided lean to it.  The straight line of the 4’ high, free-standing wall was bowed and was listing badly.  It looked as though it had gone slack in the July heat.  The wall was still holding it’s own, but might give up the fight and let go at any time.  Since there was going to be a wedding party on the property in the not-too-distant future we agreed it would be best to pull down the section in question and rebuild it.  So, that’s what I did today.

The mystery of the slumping wall preoccupied my mind as I stripped out the stone and set to work.  I immediately dismissed the woodchuck theory for lack of hard evidence.  Woodchucks do get rightly blamed for damage around a place, although it’s most often in the garden, involving the munching  of green, leafy things.  In our discussion, the customer reminded me that the grade in that area had been artificially elevated when the house was built.  Could that section of wall have been built atop un-compacted earth?  That could account for the slow motion “slumpage”  over the years.  A real possibility, I supposed, but other evidence steered me toward water.  Two roofs shed rain into the area in question.  But, there was no runnel in the earth, or signs of fill being washed through the stone work.  

As I worked, I kept looking up at the eaves, and the pitch of the metal roofs.  The stone wall was only 8’ from the house.  I tried to imagine what it would look like there on a snowy January night, and what it would sound like when the snow pack slid from the roof, cascading to the ground.  The weight of a winter’s worth of snow pressing against one side of the wall could potentially bend it without breaking it.  The increase, year after year, in the wall’s bow would be incremental.  I don’t know if my diagnosis of Chronic Avalanche Fatigue is correct, or not, but it sure was refreshing to be contemplating lofty piles of fresh white snow on such a sultry summer day.