The Weald is an area in South East England situated between the parallel chalk escarpments of the North and the South Downs. It crosses the counties of Sussex, Hampshire, Kent and Surrey. It has three separate parts: the sandstone "High Weald" in the centre; the clay "Low Weald" periphery; and the Greensand Ridge, which stretches around the north and west of the Weald and includes its highest points. The Weald once was covered with forest, and its name, Old English in origin, signifies woodland. The term is still used today, as scattered farms and villages sometimes refer to the Weald in their names.
The Weald is the eroded remains of a geological structure, an anticline, a dome of layered Lower Cretaceous rocks cut through by weathering to expose the layers as sandstone ridges and clay valleys. The oldest rocks exposed at the centre of the anticline are correlated with the Purbeck Beds of the Upper Jurassic. Above these, the Cretaceous rocks, include the Wealden Group of alternating sands and clays – the Ashdown Sand Formation, Wadhurst Clay Formation, Tunbridge Wells Sand Formation (collectively known as the Hastings Beds) and the Weald Clay. The Wealden Group is overlain by the Lower Greensand and the Gault Formation, consisting of the Gault and the Upper Greensand.
The rocks of the central part of the anticline include hard sandstones, and these form hills now called the High Weald. The peripheral areas are mostly of softer sandstones and clays and form a gentler rolling landscape, the Low Weald. The Weald–Artois Anticline continues some 40 miles (64 km) further south-eastwards under the Straits of Dover, and includes the Boulonnais of France.
Many important fossils have been found in the sandstones and clays of the Weald, including, for example, Baryonyx. The famous scientific hoax of Piltdown Man was claimed to have come from a gravel pit at Piltdown near Uckfield. The first Iguanodon was identified after a Mary Mantell unearthed some fossilised teeth by a road in Sussex in 1822. Her husband, Gideon Mantell, noticed they were similar to modern iguana teeth but many times larger; this important find led to the discovery of dinosaurs.
At the second location, you will be able to observe one of the unique outcrops of sandstone, known as Sweeps Cave. The cave itself is actually no more than two alcoves carved into the sandstone rock. It was given it’s name as they were used by local chimney sweeps to store soot.
Sandstone is sand that has been cemented together by two other elements: matrix, which is a fine-grained material that comes mixed with the sand, and mineral matter, which acts as the cement that binds the matrix and sand into rock. When the sand mixture is buried deep under the Earth's surface, the pressure of burial and slightly higher temperatures cause the minerals to dissolve or deform. The grains then become more tightly knit together, and the sediments are squeezed into a smaller volume. This process usually happens offshore from river deltas, but desert dunes and beaches can also create sandstone beds.
In rock classifications, sandstone has medium-to-large particles. The particles usually measure between 1/16 millimeter and 2 millimeters, which is one of the larger particle sizes for rocks in the sandstone/mud stone rock categories. Most sandstone is composed of quartz or feldspar because these are the most common minerals in the Earth's crust.
To claim this Earthcache, please message me the answers to these questions. You do not need to wait for a response before logging the find.
1 – During which period were the sediments of the Weald (including the Hastings Beds) deposited?
2 – What type of rock is sandstone?
3 – What is a sandstone with a high feldspar content?
4 – To prove you were at this location, please tell me either the date which is carved into the sandstone just to the left of the left hand alcove of Sweeps Cave, or if you are unable to reach Sweeps Cave, the date of birth on the memorial bench at location 1.
5 - Although not a requirement for logging, photos (without the above date) are appreciated