The slope of the line determines the date, and the closeness of fit is a measure of the statistical reliability of the resulting date.
As time passes, the "parent" radioactive elements change at a regular rate into non-radioactive "daughter" elements.
Thus, the older a rock is, the larger the number of daughter elements and the smaller the number of parent elements are found in the rock.
How can you tell the age of a rock or to which geologic time period it belongs?
One way is to look at any fossils the rock may contain. When you find layers of rocks in a cliff or hillside, younger rocks are on top of older rocks.
The first time we socialized outside the office, I was shocked when one of the people attending a small dinner party lit up when she recognized him.
“I LOVE your band, I saw you all play at least three times in high school! I had never heard of his band, “the Dismemberment Plan,” and it didn’t really sound like a band I would like.
As we started dating, I naturally inquired about his musical past.
He had been the lead singer of the Dismemberment Plan, but they had broken up in 2003 and hadn’t played a show together since 2007.
The latest high-tech equipment permits reliable results to be obtained even with microscopic samples.