The Earth altar entrance is located northeast of Varrock and south of the Lumber Yard. It is very close to the balloon transport system, which can be used with a ring of duelling to save travel time. The closest bank from the altar is near to the gate to Paterdomus.
The music track "Down to Earth" unlocks at the earth altar.
It is possible to make dust runes ,mud runes and lava runes while at this altar, at a mid success rate, so expect to lose a few runes. To make these however you require one set of elemental runes, a stack of pure essence and 2 talismans.
Note: Performing this action uses up a talisman and you will NOT get it back. For example, crafting mist runes would consume 1 water talisman PER craft
If you equip a binding necklace, your success rate when binding runes like these will increase to 100% ,giving you the ability to make as many bound runes as you have rune essence and whatever elemental runes you have with you. It has a total of 15 uses before it is broken.
E.g.: For each time you use the craft option you use a charge NOT per entrance to a runecrafting temple. So if you use 20 essence to make some steam runes, and then empty your rune pouched to make another group you will use 2 charges of your necklace.
The earth altar used to be larger requiring two clicks to craft earth runes (one to see the altar and another one to craft the runes) but after a system update its size was reduced requiring only one click to craft earth runes once inside the altar.