Portsdown Hill EarthCache
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Portsdown Hill is a long chalk hill in Hampshire, England, offering good views over Portsmouth, The Solent, Hayling Island and Gosport, with the Isle of Wight beyond.
Once you have found one of my Earthcaches, you can discover TB3Y3CB.
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Portsdown Hill is a ridge of chalk that lies to the north of Portsmouth Harbour on the South Coast of England. The north face of the hill is farmland, while much of the south is a SSSI (Site of Special Scientific Interest). The hill is on the mainland, just to the north of Ports Creek, which separates the mainland from Portsea Island, on which lies the main part of the city of Portsmouth, one of the United Kingdom's main naval bases. To the north lies the forest of Bere, with the South Downs in the distance. Butser Hill can be seen on a clear day. Southwick House is close by the north side of the hill, the HQ for U.S. General Dwight D. Eisenhower during the D-Day invasions; the generals prayed together before D-Day at Christ Church Portsdown, on the hill, which has a memorial window.
The A3(M) motorway cuts through the east side of the hill while the original A3 climbs over the centre by the "George" pub and Christ Church. The nearest train stations (from west to east) are Bedhampton, Cosham and Portchester.
There are many stories about real and imagined tunnels in the hill.
The Hampshire Basin is the traditional name for the landward section of a basin underlying the northern English Channel and much of central southern England, known more fully as the Hampshire-Dieppe Basin. The simple basin structure is complicated by localised folding. A smaller outcrop of Palaeocene and Eocene deposits occurs in a small syncline to the south-east of Salisbury. An anticline to the north of Portsmouth results in the significant chalk ridge of Portsdown Hill within the younger sediments; the London Clay to the north contains the Forest of Bere. A similar structure further east causes chalk to outcrop between Bognor Regis and Worthing, separated from the chalk of the South Downs by a belt of Reading Beds and London Clay continuing from Havant through Chichester and south of Arundel to the coast at Lancing.
Portsdown Hill, when seen from the harbour in the south, or when driving, cycling, walking or flying over, clearly shows as a ridge of pure white chalk. Quarry faces, numerous pits, the road verges, as well as bare fields, grassland and scrubland all display the white rock which underlies the countryside. The pure white chalk is surrounded by the clays and gravels of younger strata. This chalk is almost pure calcium carbonate, and is biogenic - it is composed of the calcite shells and skeletons of organisms, most of which are microscopic. Calcium carbonate is one of the major rock-forming minerals of the world; the other being silicates of various compositions. Chalk is widely used in manufacturing, as well as forming much of the basal layers of the local roads, such as the M27 which runs in front of the Hill.
There are several interesting walks on and around Portsdown Hill which can be found at www.portsdown-tunnels.org.uk http://www.portsdown-tunnels.org.uk/images/portsdown/Walks
To log this Cache
you must first answer three questions. At the given coordinates you will not find the necessary information for Question 1 & 2, however you will be able to observe what you have learned. These questions can be solved by homework. At the coordinates you will be able to answer Question 3. Then you will need to walk/drive to the base of the cliffs to take a photo showing the cliff face (with chalk & the answer to Q1 visible). If you walk, follow the road east, until you see the footpath heading down the side of the cliff face. If you drive, see waypoint to access the base of the cliff.
Question 1:
The Chalk of the Hill is frequently studded with another rock, in either sheets or layers of nodules. What is this rock? This other (black coloured) rock can be seen in sheets in the sides of the tunnel cut into the chalk at The Royal Armouries Museum, Fort Nelson (free entry), or in layers of nodules at N 50° 51.300 W 001° 05.666
Question 2:
The chalk was deposited during which Geologic Period?
Question 3:
You can see the sea from the top of the cliff. Estimate how high the top of the cliff is above todays sea levels.
Send an email with your team name to:
Portsdown.Answer1.answer2@gmail.com (Email title Answer3)
If, e.g., Sandstone was the other rock, the chalk was deposited during the Jurassic period, and the top of the cliffs are 100 metres above todays sea level, then send your answer to:
Portsdown.Sandstone.Jurassic@gmail.com (Email title 100 metres)
With the right answers you will receive log permission.
The coordinates are suitable parking to walk down the hill from. I recommend walk 2 from the Portsdown tunnels website for your view, but any view of the cliff face will be fine. You must upload a photo with your log entry of the chalk cliffs with you holding your GPS, or just your GPS if caching alone. Logs without log permission or picture will be deleted by me regularly.
Update: The auto response is temporarily not working, so you will not get an instant reply.
Enjoy exploring the hill.
Additional Hints
(Decrypt)
Lbh pna hfr lbhe TCF gb uryc lbh jvgu dhrfgvba guerr.