👉 Mudsill is a type of soil structure that forms in the Earth's crust, between the upper and lower layers of rock. It is formed by the accumulation of organic matter, such as dead plants and animals, which are broken down and dissolved into small particles, forming a network of interconnected holes or cracks. The mudsill is often found in areas with high levels of water or moisture, where the soil is exposed to the air and can become saturated.