starting about 2.500,000,000 years ago, sedimentary rocks affected by higher amounts of oxygen in the atmosphere, appear red, as though rusted. Fossils include earliest fish, but of types very different from modern ones. signs of the "tentative presence" of plants on land.Mesoproterozoic from 1,600,000,000 to 1,000,000,000 years ago. Particular importance attaches to occurred around 1,300,000,000 years ago during the late Mesoproterzoic era, after the earth's transition to a more highly oxygenated atmosphere with an ozone screen. Deposits that made Westmorland Green slate formed around 450 million years ago. About 50 million years later, the material was altered by heat and pressure (metamorphosed) to slate, during mountain-building. After many more millions of years, they resembled patches of moss a few centimeters high.So by measuring carbon 14 levels in an organism that died long ago, researchers can figure out when it died.The procedure of radiocarbon dating can be used for remains that are up to 50,000 years old.In living organisms, which are always taking in carbon, the levels of carbon 14 likewise stay constant.
The ratio of carbon-12 to carbon-14 at the moment of death is the same as every other living thing, but the carbon-14 decays and is not replaced.
Shorter than violet you would see the ultraviolet, that which gives us tans and sunburns, and then you would encounter much more dangerous X-ray radiation and finally deadly gamma rays.
Except for the energy they carry, all portions of the spectrum -- ordinary light, infrared, radio, ultraviolet -- are fundamentally the same.
It is suggested that analysis of sedimentary pyrite from the Belingwe sedimentary basin in Zimbabwe may provide evidence for bacterial reduction at this date.
2,500,000,000 to 542,000,000 years ago The Proterozoic Eon: the most recent part of the Precambrian Supereon.