Ceramics of indigenous peoples of the Americas
The clay body is a necessary component of pottery. Clay must be mined and purified in an often laborious process, and certain tribes have ceremonial protocols to gathering clay. Different tribes have different processes for processing clay, which can include drying in the sun, soaking in water for days, and repeatedly running through a screen or sieve. Acoma and other Pueblo pottery traditionally pound dry clay into a powder and then remove impurities by hand, then running the dry powder through a screen, mixing it with a dry temper, and then mixing water to create a plastic paste. In preparing the clay, potters spend hours wedging it to remove air pockets and humidity that could easily cause it to explode during firing. The clay then needs to "cure" over time.
Dartmoor Preservation Association
The china clay industry on Dartmoor was established long before the DPA was founded. The earliest record of a china clay pit refers to Hook Lake in 1502. The area was surveyed around 1827 by Cornishmen with thirty years experience in the clay industry. They obtained a 21-year lease in 1830, from the Earl of Morley who owned the land, to work the area between Lee Moor and Shaugh Moor. A rival pit was opened at Leftlake in about 1850 and at Hemerdon and Broomage in about 1855. Further pits were opened at Cholwichtown, Whitehill Yeo and Wigford Down/Brisworthy (circa 1860). Others followed at Smallhanger and Headon in the 1870s. Redlake started working in 1910. China clay pits are open cast mines that result in large holes in the ground accompanied by large waste tips. Over time, the pits become larger and more ground is needed for the waste, changing the landscape: the effect of this can be seen from space.