You don't have to go all mathematical to prove the Earths age, some geological features or how they form prove beyond any doubt how old the planet is, river canyons with a waterfall at their head is a good example, they start life as a river running off a plateau, eventually the water wears away the rock, as thousands of years pass it creates a canyon, the waterfall at the head keeps moving backwards or away from the plateau edge continually, how long for a river canyon to get 100 yds long, 1 mile long, i don't know the answer, but i do know its not 6000 years