Quick clay

Quick clay, also known as Leda clay and Champlain Sea clay in Canada, is a special kind of very sensitive clay found in many places around the world. This includes Canada, Norway, Russia, Sweden, Finland, and the United States. This clay is special because it can change shape very easily.

When it gets stressed or shaken, like during an earthquake or after a lot of rainfalls, the clay can suddenly turn from a solid-like material into a flowing liquid. This can cause big problems, leading to landslides. The ground can move quickly and unexpectedly, making it dangerous for people and buildings nearby.

This change happens because of something called soil liquefaction. This is when the soil loses its strength and behaves more like water. Small vibrations can trigger this process, turning solid ground into a slippery, flowing mass.

Quick clay is important to study. It helps scientists and engineers learn how to build safer structures in areas where this clay is found. Understanding quick clay helps people prepare for and prevent dangerous landslides, protecting lives and property.

Quick clay main deposits

Quick clay is found in countries near the North Pole, like Russia, Canada, Norway, Sweden, Finland, and Alaska in the United States. These places were covered by ice long ago during a time called the Pleistocene epoch.

In Canada, quick clay is linked to the old Champlain Sea. It is common around the Ottawa Valley, the St. Lawrence Valley, and the Saguenay River areas.

This special clay can sometimes turn from solid to liquid when it is disturbed. This can cause landslides. In Canada, quick clay has been linked to many landslides. Sometimes, earthquakes may have started these landslides.

Clay colloids stability

Quick clay is very unstable because its particles can change from a solid to a watery state when disturbed. This happens because clay particles have a negative charge and are surrounded by a layer of water molecules. In salty water, these particles stick together, but when the water becomes fresh, they spread apart, making the clay weak and unstable.

When quick clay is disturbed, like during an earthquake or heavy rain, it can lose its strength and flow like water. Adding salt can help it regain its strength by bringing the particles back together.

Formation of quick clay

Long ago, during the last ice age about 20,000 years ago, huge glaciers pushed rocks and dirt into the ocean, which had moved far inland. In this ocean water, tiny particles of silt and clay formed a special kind of soil that stayed strong because of salt in the water.

When the glaciers melted, the land rose up again, and this clay was left behind. Rainwater weakened the clay over time, making it loose and filling it with water. Usually, a layer of topsoil protects this weak clay. However, big events like strong earthquakes or heavy rain can soak through the topsoil and cause the clay to suddenly turn watery and flow like a liquid.

Main article: Flocculation
Main articles: Marine clay · Post-glacial rebound