One of the most interesting ceramic traditions of late prehistoric North America is centered in the Mississippi Valley; this community differed from preceding and contemporary Woodland groups in its level of technological adaptations. Such innovations included the introduction and widespread use of shell tempering, changes in firing temperatures, clay sources, and the use of fluxes. The firing temperature was between 800° and 900°C. It appears that the addition of salt to the shell-tempered pottery kept the ceramic ware from lime spalling and reduced or prevented vitrification. See also AATA 20-771.