Best isotope to use when dating very old samples
This paper describes in relatively simple terms how a number of the dating techniques work, how accurately the half-lives of the radioactive elements and the rock dates themselves are known, and how dates are checked with one another.
Many Christians accept this and interpret the Genesis account in less scientifically literal ways.
Many people have been led to be skeptical of dating without knowing much about it. In spite of this, differences still occur within the church.
For example, most people don't realize that carbon dating is only rarely used on rocks. A disagreement over the age of the Earth is relatively minor in the whole scope of Christianity; it is more important to agree on the Rock of Ages than on the age of rocks.
When the glass is turned over, sand runs from the top to the bottom.
Radioactive atoms are like individual grains of sand--radioactive decays are like the falling of grains from the top to the bottom of the glass.