“The Universe of Clay: Understanding Clay Through Science & Art” by Rhianna Moore, Shelagh Leutwiler, Ania Szynkiewicz
Description
Clay & People
People have used clay deposits for making pottery since the Stone Age (~16,500 years ago).
In East Tennessee, the Cherokee are People of the Clay who have used hand building techniques to make pots, vessels and pipes for hundreds of years.
Pottery making traditions continue at Mighty Mud by a diverse group of artists who have found their home in the Knoxville area.
Clay Formation
Clay minerals are a family of fine-grained hydrated silicates comprised of silica, aluminum, magnesium, oxygen, and hydrogen. They are formed as a result of interactions between water and igneous rocks at or near Earth’s surface. Collectively these interactions are known as “weathering”.
Two modes of clay deposit formation can be distinguished in nature. Primary clays are formed in situ on hill slopes where water percolates through soil and reaches shallow bedrock. Secondary clays undergo long-distance transport in rivers and streams, and are eventually deposited in lakes and seas, making thick, layered deposits. Pottery is created with secondary clay deposits but in some instances primary clays are used to make clay paints.
Clay mineral type is strongly linked to climate at the time of formation. For example, smectite clay commonly forms in arid, cold climates and kaolinite in warm, humid climates, like here in the southeastern USA.
Clay on Mars
Clay minerals have fascinated planetary geologists who study the surface of Mars using rovers and orbiters. Clay minerals are the main indicators of past climate and hydrothermal activity on Mars.
So far, primary clays are the majority of clays detected on Mars, usually on steep hill slopes and crater walls. Small quantities of secondary clays are present in lake-type deposits inside of craters. The lack of secondary clays is likely due to the cold climate and minimal interaction with water in the past.
Consequently, it would be difficult to make pottery on Mars as we do in Mighty Mud because Mars lacks thick deposits of secondary clays. It is possible that small pieces of pottery could be made with primary clays after separating them from accompanying sand and rock fragments.
Nearest Future
The new rover Perseverance is on its way to Mars now. It will land in February 2021 and investigate clay minerals in Jezero Crater that had been filled with a large lake ~3 billion years ago.
Perseverance will also collect soil and rock samples to be returned to Earth in the next 10-15 years.
Clay minerals from Mars’ surface will be used to learn about climate and water activity in Jezero Crater, and may also help in understanding the origin of life.
Some scientists are exploring the idea that clay minerals may have played a fundamental role in the origin of life on Earth because of their unique crystal structure, a process known as abiogenesis. Their ability to absorb, concentrate, and organize materials into organic molecules makes them ideal templates for developing complex structures like proteins and even DNA.
Shelagh Leutwiler – Visual Artist
Anna Szynkiewicz – Associate Professor, University of Tennessee
Rhianna Moore – Graduate Student, University of Tennessee
