Wild Clay

White, Blue and Red Clay Bodies

Currently I am in northern British Columbia, on the ancestral lands of the Tsimshian people of Kitsumkalum, researching clay in the flat-bottomed and steep-walled fjord valley known as the Kitimat-Kitsumkalum trough.

Just below the surface there is a thick layer of marine clay left over from the last Pleistocene glaciation, somewhere around 12,000 years ago. I am learning that marine clay was formed when the glaciers sat on this land and forced it down below sea level. The clay particles created from weathering, the grinding of the glaciers and other geological processes have small holes that were saturated with salt water. When the glaciers retreated and the land rose above sea level leaching and diffusion by freshwater gradually lowered the salinity and some types of clay and mixtures of silt and clay became more prone to collapse because the repulsive forces between the particles increased. These deposits are called ‘quick’ or ‘sensitive’ clays and are unique to this region. 

In the photo you will see clay body tests from three foraged clays ~ white, red, and blue. When I did the soil test with water for each of these clay bodies I noticed there was only one layer that formed and wondered if that is because of the influence of salt water. Salt water silt and clay particles form aggregates that settle together in a random pattern ~ unlike freshwater environments where clay particles settle more slowly than silt and accumulate in stacks of plates parallel to one another.

I will bisque fire the test samples this week to see what effect heat has on each of them.

Reference: Slaymaker, O., 2017. Landscapes and Landforms of Western Canada. Springer International Publishing Switzerland.