There is no need to stray off the footpaths to complete any part of this Earthcache, and no benefit would be gained by doing so, a clear view is available from many points along the footpath, so please don't go down the quarry itself. This cache can not be completed at night.
Geology
Irchester is sited on the hills adjoining the flood plain of the River Nene. In the predominantly agrarian medieval period, this combination of access to fertile, if flood-prone, valley bottom soils and drier (but heavier and more clay-rich) hillside/ hilltop soils seems to have been good for a mixed agricultural base. The clay-rich hilltop soils are primarily a consequence of blanketing of the area with boulder clay or glacial till during the recent glaciations. On the valley sides and valley floor however, these deposits have been largely washed away in the late glacial period, and in the valley bottom extensive deposits of gravels were laid down, which have largely been exploited for building aggregate in the last century.
Iron Ore
The most economically important aspect of the geology of the area is the Northampton Sands ironstone formation. This is a marine sand of Jurassic age (Bajocian stage), deposited as part of an estuary sequence and overlain by a sequence of limestones and mudrocks. Significant amounts of the sand have been replaced or displaced by iron minerals giving an average ore grade of around 25 wt% iron. To the west the iron ores have been moderately exploited for a very long time, but their high phosphorus content made them difficult to smelt and produced iron of poor quality until the development of the Bessemer steel making process and the "basic slag" smelting chemistry, which combine to make high quality steelmaking possible from these unprepossessing ores.
The Northampton Sands were a strategic resource for the UK in the run-up to World War II, being the best developed bulk iron producing processes wholly free from dependence on imported materials. However, because the Northampton Sands share in the regional dip of all the sediments of this part of Britain to the east-south-east, they become increasingly difficult to work as one progresses east across the county.
Logging Requirements
To log this cache you will need to walk from one end of the Geological feature to the other, making observations along the way.
Please send the answers to the following questions to the link in my profile, stating your username and show email so I can reply and confirm correct answers.
1. What does NSI stand for?
2. Describe the colour of the Geological feature, and tell me if it is lighter or darker at the top.
3. What is the approx. distance from one end of the feature to the other, in Yards or Meters only please?
4. How high is the exposed Geology at its highest point?
5. What might of been produced from the extracted products of this old quarry?
6. It would be great if you post a photo of you on the trail, but is optional.
Park Information
•Superb children's play and activity areas supported by East Midlands Development Agency
•Quarryman's Rest cafe open every day except Christmas Day
•Free Admission - car parking charge of £2.50 on pay and display basis
•Park and upper car park open all day, every day
•Toilets and lower car park open 9:00am to 5:00pm daily (except Christmas Day)
•Designated picnic areas
•Circular, waymarked and hard-surfaced trails through woodlands
•Open spaces for ball games, and dog walking
•Quiet areas to relax and enjoy the peace or watch the local wildlife
•Wheelchair loan
•Orienteering trails
•High ropes adventure trail
•Spirits of Wood chainsaw artist based in the park
•Dinosaur Adventure Trail
I hope you have fun and learn something at the same time whilst completing my Earthcache.
FTF Honours go to Lorri-Ann & Kev & Scott Cache Seekers
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