The Fontaine de Vaucluse was formed after the Messinian salinity crisis, during the latter part of the Messinian age of the Miocene epoch, from 5.96 to 5.33 Ma (million years ago), which caused the depth of the exsurgence.

Above the spring there is a 230-metre (750 ft)-high limestone cliff with innumerable breaks and faults.
This acts as a reservoir, a karst aquifer, in which the water circulates along the discontinuities until it meets a barrier of limestone and clay.

The spring, which feeds the River Sorgue, is the only exit point of a 1,100-square-kilometre (420 sq mi) underground basin, which captures waters from Mont Ventoux, the Vaucluse Mountains, the Albion Plateau and the Lure Mountain.
The water of this exsurgence contains an average of 200 milligrams per litre (0.00012 oz/cu in) of calcium carbonate, and has an annual flow of about 700,000,000 cubic metres (2.5×10¹⁰ cu ft), so the reservoir loses 50,000 cubic metres (1,800,000 cu ft) of limestone each year.

This karstification phenomenon acting on the surface of the impluvium, removes an annual volume of 45 cubic metres (1,600 cu ft) per square kilometre, which disappears after being dissolved in the water.
That figure becomes more meaningful when calculations show that, in 3.5 million years, the Vaucluse Mountains, the Albion Plateau, and the Lure Mountain, will have had their thickness reduced by 1,500 metres (4,900 ft).
The Fontaine de Vaucluse was formed after the Messinian salinity crisis, during the latter part of the Messinian age of the Miocene epoch, from 5.96 to 5.33 Ma (million years ago), which caused the depth of the exsurgence.
Above the spring there is a 230-metre (750 ft)-high limestone cliff with innumerable breaks and faults. This acts as a reservoir, a karst aquifer, in which the water circulates along the discontinuities until it meets a barrier of limestone and clay.
The spring, which feeds the River Sorgue, is the only exit point of a 1,100-square-kilometre (420 sq mi) underground basin, which captures waters from Mont Ventoux, the Vaucluse Mountains, the Albion Plateau and the Lure Mountain. The water of this exsurgence contains an average of 200 milligrams per litre (0.00012 oz/cu in) of calcium carbonate, and has an annual flow of about 700,000,000 cubic metres (2.5×10¹⁰ cu ft), so the reservoir loses 50,000 cubic metres (1,800,000 cu ft) of limestone each year. 
This karstification phenomenon acting on the surface of the impluvium, removes an annual volume of 45 cubic metres (1,600 cu ft) per square kilometre, which disappears after being dissolved in the water. That figure becomes more meaningful when calculations show that, in 3.5 million years, the Vaucluse Mountains, the Albion Plateau, and the Lure Mountain, will have had their thickness reduced by 1,500 metres (4,900 ft).
Fontaine de Vaucluse (spring)