Natural arches commonly form where inland cliffs, coastal cliffs, fins or stacks are subject to erosion from the sea, rivers or weathering (subaerial processes). ... The alcoves erode further into the formation eventually meeting underneath the harder caprock layer, thus creating an arch.
It's a salt of carbonic acid. it's called sodium bicarbonate. It contains the anion HCO3. It usually refers to bicarbonate of soda (baking soda), a white powder that is a common ingredient in antacids. It is also a byproduct of your body's metabolism.
