The Geology of Bedgebury
Bedgebury is on Tunbridge Wells sandstone that is between 134 to 140 million years old. It is a mixture of siltstone, sandstone with some fine clay; this variety was caused by the rise and fall of sea level. The dust on your car or bike in summer is evidence of how fine grained this can be and you just have to look at a cyclist in wet weather to see how muddy it can get!
What little nutrients there were leached out to form bands of dark rusty black iron ore bands (pictured) running through the rock. These nutrient poor soils known as podzols are the reason that historically the Weald was left forested; but the combination of iron ore and wood to make charcoal made the Weald one of the most important industrial areas in the country until the 18th century.
All of the lakes and ponds in the forest were built to provide a water supply to the foundry near Bedgebury House.
The soil in the Pinetum is very acidic with pH ranging from 7.1 to 3.5. Fortunately many conifers can survive in acid conditions and rhododendrons positively thrive hence our ongoing battle with the invasive R. Ponticum. The heath area near the Glory Hole is another example of plants that like acidic soils.
Bedgebury is situated in a much larger area of the south-east, known at the Weald. 150 Mybp (million years before present) the Weald was at the northern edge of a huge fresh water lake with deposits of sand, silt and clays being deposited in rivers, estuaries and deltas. Around 100 Mybp, this compacted and sank filling the basin with seawater becoming part of the Tethys Sea and allowing chalk deposits to build up from the shells of planktonic micro-organisms known as coccolithophores. Later, starting around 50 Mybp, as a by-product of the collision of Italy with Europe, the Weald was uplifted in a huge dome up to 1000m above sea level. This was eroded and flattened during and after the Ice Ages by the massive amounts of melt water; leaving older rocks exposed in the centre with the younger chalk (N & S Downs) around the outside.