This explanation can be called the mature-earth creation hypothesis.
In summary, the age of the earth as calculated by radiometric dating methods remains one of the more problematic issues for creationists.
Potassium atoms vary in their numbers of neutrons, resulting in atoms with different masses (called isotopes).Some possibilities have been proposed, but they are not compelling because they often often invoke supernatural activity or unknown mechanisms. Another approach to explaining ages of millions of years is to propose that the rocks of the earth are very old because the planet was created long before life was placed on it. The Bible does not give an age for the Earth, nor is any theological point drawn from the age of the Earth, so it may not be as important as some of the other issues.Most scientists believe the Earth is about 4.5 billion (4,500,000,000) years old. Some creationists have attempted to reconcile this figure with the creation in Genesis by proposing that the rocky, lifeless planet was created long ago (perhaps 4.5 billion years), and God created life on this planet later (perhaps 6,000 to 10,000 years ago), when it suited His purposes to do so.