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 Monument skull is the commonest of all "memento mori" symbols in funerary art. It was also defined as the philosophical vessel ("Vas Philosophorum") in Renaissance-era alchemy. The role of the Quaternity in religious symbolism is discussed in depth in the writings of the Swiss psychologist Carl Gustav Jung. In essence, the Layer monument's four figurines represent spiritual entities which agree with Jung's analytical psychology, that the psyche moves toward individuation in fours (made up of pairs of opposites). The Layer Monument The Layer monument is an early 17th-century polychrome marble mural monument (320 × 350 cm) erected to the memory of