The amount of radioactive carbon (14C) that had been in the organism when it was alive begins to decrease at death as it loses nuclear particles through radioactive decay.In effect, the "clock" starts ticking when death occurs. After 5,568 years, half of the original amount of 14C in the living organism remains.

dating sediment layers-8

But how does one determine an age for the initial set of rocks?

One might assume those ages are obtained either directly or indirectly from radioactive dating techniques.

Because deep-ocean sediments are so thick, secular scientists assume they were deposited over millions of years.

This might seem reasonable since sediments accumulate very slowly today.

Knowing which events came before or after others allows scientists to analyze the relationships between the events.

For example, archaeologists might date materials based upon relative depth of burial in a site.

The archaeologists record and analyze the changes in types and styles of human-made items from different levels according to the principle explained below.

Sediments are usually laid down in horizontal beds.

Any observable tilting or swirling is due to disruption of the process. Material that intrudes or cuts into a horizontal bed is assumed to be younger than the material that is disrupted.

Consider a lake that dries out or somehow contains older sediments that are washed into it.

In theory, yes, but secular scientists have been known to reject such ages if they contradict the evolutionary story the scientists think the fossils are telling—even if the dates from multiple methods agree with one another.