This proved to be a good environment for Cyanobacteria to evolve the first photosynthetic metabolic pathways which gradually increased the oxygen portion of the atmosphere, changing it to what is known as an oxidizing atmosphere.
atmosphere | Earth's atmosphere | Atmosphere | Upper Atmosphere Research Satellite | Space and Upper Atmosphere Research Commission | Sulfate-reducing bacteria | Stellar atmosphere | Joint Institute for the Study of the Atmosphere and Ocean | Guinguette atmosphere in the ''Luncheon of the Boating Party | Atmosphere (music group) |
The brick is made from the local red clay, Etruria marl, which when fired at a high temperature in a low-oxygen reducing atmosphere takes on a deep blue colour and attains a very hard, impervious surface with high crushing strength and low water absorption.