I do wish they would not describe things in that manner, for example, my garden is planted in 1.2 billion year old dirt. (See what I mean) Now, I really do have some 7,000 year old wood.
Yes, but what they meant was they know from the strata of the layers of soil and clay that that level of clay was deposited 125 million years ago. 100 feet is a long way down. There was an electronic resistor-like part discovered in rock several years ago plus other artifacts found deep in the earth. And there is biblical support for an event that wiped out everything millions of years ago, much more devastating than Noah's flood.
These links test the limits of one's open-mindedness as to the history of intelligent existence on the earth. :^)