Wealden Lake was a freshwater lake which existed over the lands now considered to be northern France and southern England during the early Cretaceous (around 140 million years ago). Alluvial plains and deltas spread from the uplands surrounding the area where London now stands and eventually ran into this great lake.
Global tectonic shift during the mid to late Cretaceous (especially in the Maastrichtian) raised, tilted and thereby drained Wealden Lake. It would have been around the size of the Caspian Sea at its best preserved extent during the early Cretaceous.
Strata associated with Wealden Lake have been prosperous for paeleontologists, providing the mysterious Baryonyx dinosaur among many other finds.