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.
<span>how plants make sugar and energy from water, air and sunlight into energy (a.k.a. ATP) to grow and develop</span>
That would be CO2 also known as carbon dioxide.