To recap, springs arise from the base of a permeable, water-bearing rock (the aquifer) that overlies a less permeable rock (the aquiclude). Groundwater accumulates within the aquifer above the aquiclude, to an extent that depends on the aquifer’s permeability. The top surface of this body of water is the water table – it is not flat but curves downward towards the edge of the aquifer, where springs emerge.
There are two aquicludes in the local area. The most productive locally, in terms of the number of springs it generates, is the Grey Chalk near the junction between the West Melbury Marly Chalk and the Zig Zag Chalk. The springs at St Eadburg’s Well, the one below Rectory Lane, and the Eastbrook Spring in Etchinghill all issue close to this boundary. The seasonal roadside springs between Broadstreet House and Green Banks also flow from this unit.
The second aquiclude, regarded as the main aquiclude regionally, is the Gault at the base of the Chalk. Local examples include the springs at Postling (in a private garden) that feed into the East Stour, and the springs issuing from the base of the escarpment immediately east of Etchinghill, which feed into the Seabrook Stream. Seasonal springs also occur along the Beachborough road and on the Postling road north of its junction with the A20 Road.
A characteristic of Chalk, which also affects the flow of springs, is that it is soft and soluble. Once a spring starts to flow, groundwater flowing towards the spring enlarges the flow path by erosion and dissolution, which increases the flow and further enlarges the flow path. So, they are self-perpetuating and can become permanent features. (This characteristic is used by operators of water extraction boreholes in Chalk. As a well is “developed”, the water yield increases.)
In the urban environment, some spring water may find its way into the permeable backfill of service trenches in the road, or into the road’s granular sub-base. These then effectively act as “French Drains” – a primitive type of land drain comprising a gravel-filled trench used to collect and divert groundwater flow. Where this happens, the water can erupt through weak points in the road construction as “road springs”. Occasionally, during periods of high groundwater levels, water may issue from manhole covers. This may be evidence that groundwater has penetrated through discontinuities in the pipework and that the downstream pipework’s discharge capacity has been exceeded, causing the excess to erupt around manhole covers.
Locally, these road springs are particularly obvious in winter, when the water table is high and roads cross the Gault-Chalk boundary. Good examples can be seen in the lower part of Beachborough and near the bottom end of Sandling Road. When the water table is sufficiently high, springs issue from perched water tables higher up the slope within the permeable parts of the West Melbury Marly Chalk Formation. Good examples of these can be seen near Broadstreet on the south side of Lyminge and on the north side of Etchinghill. The geological maps show linear deposits of Head at both locations, which may indicate ancient water courses.
The alternation of permeable and impermeable beds, characteristic of the lower part of the Grey Chalk, creates the conditions for the development of artesian pressure. Groundwater supplied from a higher-elevation source is under pressure if it is trapped beneath an impermeable layer. Where this water reaches the surface through discontinuities in the capping layer, it issues under pressure sufficient to produce a noticeably rapid flow. It is likely that some of the road springs are under artesian pressure, as suggested by their high flow rate.
A way to keep an eye on the height of the water table, if you are interested in such things, is to observe the progression upslope of the highest spring eruption as winter progresses, and then its regression in spring. (This method suggests that the water table during the winter of 2024 was particularly high.)
Andrew Coleman
Rev. 14/10/2026
