Dry Sandford EarthCache
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Dry Sandford Pit attracts a diversity of plant and animal life. The exposed pit cliffs are brilliant for spotting solitary bees and wasps, as well as fossil remains from southern Britain's ancient under-sea past.
Dry Sandford Pit is famous among geologists for its sandstone exposures where Jurassic fossils can be found, and biologists love it for the unique combination of woodland, ponds and a fen that plays host to the nationally rare Southern Damselfly and the carpets of marsh helleborine orchids.
The old quarry at Dry Sandford Pit exposes part of a sequence of limestone rocks known as the Corallian Beds, laid down during the Middle Oxfordian Stage of the Jurassic, some 140 million years ago. The original sediments were deposited in shallow coastal waters close to coral reefs. The layered rock succession seen here includes parts of three main units of the Corallian; the Lower Calcareous Grit; the Lower Trigonia Bed of the Highworth Grit Formation; and the Third Trigonia Bed, Urchin Marl and Coral Rag of the Osmington Oolite Formation. (the upper Trigonia Bed, Pusey Flags and Highworth Grit and Clay) are missing from the succession seen here, indicating that a major period of erosion took place in this area during the deposition of the Oxfordshire Corallian Beds. With the exception of the Urchin Marl and the Coral Rag, these beds contain a rich and important fauna of fossil ammonites. These rocks have yielded a diverse array of fossil marine creatures including brachiopods, ammonites and corals. The ammonites have been important in enabling the rocks to be compared and dated with other sequences of similar age throughout southern Britain.
The middle Oxfordian Stage is sub-divided into two time zones, each defined by the occurrence of a diagnostic species of ammonite one zone is characterised by Cardioceras densiplicatum and the other zone by Cardioceras tenuiserratum; both zones are represented at Dry Sandford Pit. As such, the site is invaluable as a middle Oxfordian reference section against which other Corallian sections, both locally and nationally, can be compared.
Approximately 7.50 hectares in area, it is a tranquil place with a convenient car park in Dry Sandford. It is part of a complex of four reserves - known as the Cothill reserves - which includes Parsonage Moor, all within walking distance of the recommended car parking area.
In this area there are known to be at least 42 different types of plants and 18 types of insects, along with various vertebrae and birds too.
To log this cache you must visit the locations listed and answer the following questions.
Feel free to log straight away as there is no need to wait for a reply to your answers. However, failure to provide the answers within a reasonable time limit may invalidate your log which subsequently may be deleted!
Q1 - What mineral is contained in the fell water to encourage plants growth and explain why you think it is important?
Q2 - How do you think the grey layer of limestone is formed and explain your answer?
Q3 - Name the 3rd layer which make up the "Limestone section" of rockface and what is your conclusion about how it is formed? (Observe the rockface to see what is contained within the layers for a clue).
Feel free to post a picture of yourself or GPSr at the rockface as it will not be a spoiler
Additional Hints
(Decrypt)
Sbyybj gur sbbgcngu nebhaq gur onfr bs gur ebpxsnpr naq ernq gur abgvpr obneqf!