Ozone as concentrations in μg/m. The study of ozone concentration in the atmosphere started in the 1920s. The highest levels of ozone in the atmosphere are in the stratosphere, in a region also known as the ozone layer between about 10 km and 50 km above the surface (or between about 6 and 31 miles). However, even in this "layer", the ozone concentrations are only two to eight parts per million, so most of the oxygen there is dioxygen, O, at about 210,000 parts per million by volume. Ozone in the stratosphere is mostly produced from short-wave ultraviolet rays between 240
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