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Re: ~*~Aamney Saamney Aak Key 2~*~
Hmmm bohat clever bunanay ki kooshish ki he aap ne...lekin me aap se bhi ziada clever hoon :lpop:
chalein mein aap ko kuch easy ker ke batata hoon suppose koi insaan aaj se 800 years pehlay mara tha...us ki deadbody kisi pahaar ki ghaar mein mili...ub is pe fossels walay rules bhi apply nahi hon ge...sedimentation method, magnetic field aur radio-isotopes walay process bhi yeh measure kerne ke liye kaam nahi aaein ge ke aaya yeh insan kitnay saal pehlay mara...us ke liye aik aur special process hota he...us process ka naam bataiye...:lpop:
Originally posted by fari
Paleontologists use many ways of dating individual fossils in geologic time.
:lpop: :lpop: :lpop: jawab dhoond lijiya angrazi mai ha app ko samjh a jay ge na:mm: :mm: :lpop:
- The oldest method is stratigraphy, studying how deeply a fossil is buried. Dinosaur fossils are usually found in sedimentary rock. Sedimentary rock layers (strata) are formed episodically as earth is deposited horizontally over time. Newer layers are formed on top of older layers, pressurizing them into rocks. Paleontologists can estimate the amount of time that has passed since the stratum containing the fossil was formed. Generally, deeper rocks and fossils are older than those found above them.
- Observations of the fluctuations of the Earth's magnetic field, which leaves different magnetic fields in rocks from different geological eras.
Dating a fossil in terms of approximately how many years old it is can be possible using radioisotope-dating of igneous rocks found near the fossil. Unstable radioactive isotopes of elements, such as Uranium-235, decay at constant, known rates over time (its half-life, which is over 700 million years). An accurate estimate of the rock's age can be determined by examining the ratios of the remaining radioactive element and its daughters. 
For example, when lava cools, it has no lead content but it does contain some radioactive Uranium (U-235). Over time, the unstable radioactive Uranium decays into its daughter, Lead-207, at a constant, known rate (its half-life). By comparing the relative proportion of Uranium-235 and Lead-207, the age of the igneous rock can be determined. Potassium-40 (which decays to argon-40) is also used to date fossils.
:lpop: :lpop: :lpop: jawab dhoond lijiya angrazi mai ha app ko samjh a jay ge na:mm: :mm: :lpop:
chalein mein aap ko kuch easy ker ke batata hoon suppose koi insaan aaj se 800 years pehlay mara tha...us ki deadbody kisi pahaar ki ghaar mein mili...ub is pe fossels walay rules bhi apply nahi hon ge...sedimentation method, magnetic field aur radio-isotopes walay process bhi yeh measure kerne ke liye kaam nahi aaein ge ke aaya yeh insan kitnay saal pehlay mara...us ke liye aik aur special process hota he...us process ka naam bataiye...:lpop:
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