Wikipedia radiocarbon dating uranium lead dating
Using logs recovered from old buildings and ancient ruins, scientists have been able to compare tree rings to create a continuous record of tree rings over the past 2,000 years.
This tree ring record has proven extremely useful in creating a record of climate change, and in finding the age of ancient structures. The thick, light-colored part of each ring represents rapid spring and summer growth.
Of all the isotopic dating methods in use today, the uranium-lead method is the oldest and, when done carefully, the most reliable.
Unlike any other method, uranium-lead has a natural cross-check built into it that shows when nature has tampered with the evidence.
So when a mineral grain forms (specifically, when it first cools below its trapping temperature), it effectively sets the uranium-lead "clock" to zero.Each dark band represents a winter; by counting rings it is possible to find the age of the tree (Figure 11.22).The width of a series of growth rings can give clues to past climates and various disruptions such as forest fires.The level of atmospheric Radiometric dating in general, of course, poses a huge problem for people who believe that the universe is 6000-odd years old.A favorite tactic of Young-Earthers involves citing studies which show trace amounts of Indeed, this results from a unique decay mode known as "cluster decay" where a given isotope emits a particle heavier than an alpha particle (radium-226 is an example.) This fact is extremely inconvenient and creationist literature, accordingly, usually does not mention it.
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Uranium comes in two common isotopes with atomic weights of 235 and 238 (we'll call them 235U and 238U).