Ozone depletion as the International Day for the Preservation of the Ozone Layer, or "World Ozone Day", to commemorate the signing of the Montreal Protocol on that date in 1987. Ozone depletion Ozone depletion describes two related events observed since the late 1970s: a steady lowering of about four percent in the total amount of ozone in Earth's atmosphere (the ozone layer), and a much larger springtime decrease in stratospheric ozone around Earth's polar regions. The latter phenomenon is referred to as the ozone hole. There are also springtime polar tropospheric ozone depletion events in addition to these stratospheric events. The main
The Layer Quaternity other. As such, the Layer Quaternity may be viewed as exemplary of Renaissance-era psychology. Its four highly-symbolic figurine entities are simultaneously, a 'map' of the psyche, and a highly-original alchemical mandala in western funerary art. The Layer Quaternity The Layer Quaternity are four marble sculpture figurines approximately in height located on the two columns of the Layer Monument, an early 17th-century polychrome mural monument () which was installed in the Church of Saint John the Baptist, Maddermarket, Norwich to the memory of Christopher Layer (1531–1600). The quartet of figurines sculptured in marble, "Pax, Gloria, Vanity, Labor" exhibit primary thematic concerns