The chondrule and phosphate dates are interpreted as the timing of cessation of Pb diffusion during cooling following metamorphism in chondrite parent bodies.
The difference in estimated closure temperatures, ∼950–1150 K for pyroxenes, and 700–800 K for phosphates (temperature estimates are based on published diffusion rates for Pb in pyroxenes and apatite), allows evaluation of the average cooling rate at 26 ± 13 K/million years for the Richardton parent body over the period of 4563–4551 my.
Matchmakers now needed a keen eye for a couple who could live together harmoniously and enjoy each other's company—as well as each other's inheritance.
The first matchmaking agencies in Britain appeared in the 1600s when parish vicars played a crucial role in matching their parishioners with a spouse from the same social class.
Despite cold takes that Tinder perpetuates hook-up culture and is killing romance as we know it, the app has been downloaded 100 million times and is obviously doing something right.
In four fast years, it’s amassed users in 196 countries and is available in 30 languages.
Before then, the Bible had provided the only estimate for the age of the world: about 6,000 years, with Genesis as the history book.
Chondrules and milligram-sized fractions of pyroxene-rich chondrule fragments contain highly radiogenic Pb and concordant or nearly concordant U-Th-Pb isotopic systems, and are suitable for precise Pb-Pb age determinations.Using fossils as guides, they began to piece together a crude history of Earth, but it was an imperfect history.After all, the ever-changing Earth rarely left a complete geological record.Writers such as Jane Austen offered a biting, and often hilarious, social satire to send up the process in their novels.Austen was modernist in her belief that one should marry for love, and clearly shows her contempt for matchmaking in where Elizabeth talks about her mother, Mrs Bennet, who only has eyes for money (and the odd handsome soldier).But for humans whose life span rarely reaches more than 100 years, how can we be so sure of that ancient date? Even the Greeks and Romans realized that layers of sediment in rock signified old age.