No Dirt

At our place on the south edge of the Precambrian Shield, mica schist is more common than ordinary dirt. Gardening is a challenge with no dirt.


Aileen’s gardening is restricted to ‘raised beds’ confined in plank boxes. The dirt in the boxes is captured from nearby low spots where fragments of bedrock and detritus from trees and other plants have settled. Production of soil for the box gardens was aided by the local potteries. Aileen saved clay scraps from her potting and she begged more clay scraps from the local commercial potter. To add to this clay component, we captured fine fragments of the Precambrian Shield that had washed down the Salmon River and had become part of nearby silt beds.


When the water level gave access to these silt beds, we approached by canoe with many large buckets and shovels. Pure native silt. Rich with nutrient ions and vital minerals adsorbed onto the colloidal particles and the organic matter. But the laws of physics and hydrology had been overlooked.


As we filled buckets with the heavy, saturated sediment, the canoe went progressively aground. With all buckets filled and us onboard, the vessel would not budge. Stepping out and pushing on the gunwale simply drove my boots deeper into the silt bed. I was able to stand on the blade of the round-mouthed shovel to slow the sinking but still no canoe movement. Aileen got out onto some vegetation but I still could not move our barge. Eventually with both of us ‘wiggling’, the back and forthing got enough water under the keel to allow slight progress.

Thus, we got afloat, all aboard and back to the raised garden bed to deliver the ‘black gold’.


On the Precambrian Shield, minerals erode slowly from the bedrocks and, together with organic fragments move downhill with the runoff. The products of erosion and the products of organic growth flow downhill and accumulate in depressions, lake beds and river shores. Rarely, accumulation of this mix of rock parts and plant parts can fill hollows large enough for a market garden. But agriculture here is mainly on river flood plains or areas of glacial till left by the moving ice. Without the added organic fragments, the rate of supply of new nutrients eroded from the bedrock would be unworkably slow.


As rain, frost, ice and the mechanical forces of tree roots break up the bedrock scant dirt is started. Plants seize on it and help to hold it. Over many seasons of growth, the dead plant material becomes a major force on developing dirt, keeping dirt uphill and adding plant parts to it from the air above.