Rocking in the big City #2
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A remnant of the Ice Age from the Lake District right here in the heart of the City..! but what is it and how did it get here ??
This rock or 'glacial erratic' as it should be known, originates from Borrowdale in the Lake District is located in the Quadrangle of the University in Manchester, behind the museum, the rock is over tons of andesite and was thought to have possibly been dug up during the canal excavations, the Rochdale Canal's main Manchester basin is very close by, the plaque nearby the rock states that the rock was excavated from 28ft under the ground but the canal is not mentioned.
But how did it get here from Borrowdale ?
Back in the Ice age, during the early Devensian period, ice formed only in Cumbria. By 22,000 BP the northwest of England was covered by ice
emanating from Scotland and the Lake District. The ice sheet was warmbased, with subglacial water movement within
tunnel valleys. As the climate warmed the ice receded northwards, leaving moraines and stagnant ice features. During the
later stages of recession, subglacial water began to move through the thick till bed, and deformation of this sediment into
drumlins occurred. This process was aided by the marine inundation of the Irish Sea basin, forming a tidewater glacier
margin, and causing rapid drawdown and calving of icebergs. After the main ice sheet had disintegrated, a cold snap led
to the reformation of ice in the Pennines and Lake District.
Rocks such as this one were transported from the Lake District areas within the huge moving masses of ice and were deposited wherever the icebergs came to rest before finally melting.
Evidence of the last glaciation to affect Northwest England would suggest this erratic was probably deposited in this area between 25,000 and 19,000 years ago.
This rock is a lot larger than the other erratic in Manchester City centre as you will see when you visit.
To log this Earthcache please EMAIL ME the answers to the following questions, and also post A PHOTOGRAPH IN YOUR LOG with you OR your GPSR with the erratic rock:
1. On the plaque please tell the junction of which roads the rock was excated from.
2. Please estimate the height of the rock
3. The rock is Andesite, please name 2 of the minerals found commonly in the make up of this rock (you will need to research for this information)
Please be aware the due to the high buildings the coordinates may well be slightly out, if you get to the area however you should be able to find it, and the plaque without a problem, if in doubt ask anyone nearby or in the museum, please post any better coordinates in your logs should you be able to take a better reading, the rock is pretty big, clearly visible and is plinthed so stands out.
I hope you enjoy your trip back through time, if so - why not visit my other nearby Earthcache, and learn some more about the past with 'Rocking in the big City#1', it is approximately 10 minutes walk away from this site, amazingly yet another erratic, smaller in size than this one, but formed of a different of stone not normally found in this area - carried here by the might of the glaciers up to 25,000 years ago ! In the same ice sheet perhaps ???
PLEASE NOTE: I receive a very high number of Earthcache emails, I can’t reply to them all otherwise I’d be doing nothing else all day, as has always been the case there is no need to await a reply from me regarding your answers…. However due to numerous people thinking they can just log these caches without emailing any answers, and/or completing the required tasks these will be picked up, and the logs will be deleted without further communication. To facilitate this Please email your information either before, or AT THE SAME TIME OF LOGGING THE CACHE, Thanks.
Additional Hints
(Decrypt)
Vg'f Cyvagurq va gur DHNQENATYR va gur Havirefvgl, whfg bss Bksbeq Ebnq.