Creation and Time by Hugh Ross

[pelathais]

Originally Posted by Orthodoxy

14 Scientific Reasons to Believe in a Young Earth (Answers in Genesis) http://www.answersingenesis.org/docs/4005.asp

11) Too much carbon-14 in deep geologic strata

"New 14C is formed from background radiation, such as radioactivity in the surrounding rocks. In some cases, 14C from the atmosphere can contaminate a sample. A few processes that can add "modern" 14C to coal are:

• Sulfur bacteria, which commonly grow in coal.
• Secondary carbonates from groundwater that form on fracture surfaces.
• Whewellite, a carbon-containing mineral, that often forms as coal weathers.

Minute amounts of contamination from these sources can cause apparent ages around 50,000 years, which is near the limit of the maximum age that carbon dating can measure."

http://www.talkorigins.org/indexcc/CD/CD011_6.html

For a more verbose explanation see:

http://www.talkorigins.org/faqs/c14.html