What evidence for the age of the earth is indicated by the fact that sedimentary rock is found on mountain tops?

Undisturbed rock formations on mountain tops are basically an indication of the Earth's age. This can be supported by the law of proposition. This law states that the youngest sediments or rock are found at the top of the sequence and the oldest are found at the bottom - given they're undisturbed. So the higher mountain tops or rocks formation are, the more we can say that the Earth is indeed very old.