Treasure pool

[Phil FK 3]

During my summer holiday trip back home to the UK I took my son on a tour of Ingleborough caves in Yorkshire. There was this pool where visitors had thrown coins. The guide said visitors had been doing this since the caves opened to the public in 1837 and nobody has disturbed them since then.

Wouldn’t mind an hour in that pool. And a big wheelbarrow.

[Rob 3,152]

Except that the water will be slightly acidic. Maybe not such a good chance of picking out a gem.

[Nutsaboutcoins 105]

My science might be a bit rusty, but wouldn't the limestone neutralise the acid?

[jelida 1,317]

Certainly the stalagtites and solid flows would suggest lime bearing water, thus alkaline; from my MD experience bronze seems to survive better in alkaline environments, but would still patinate over time. Where I have found Roman coins, shiny and uncorroded as on the day they were dropped, is in the anoxic mud of the Severn Estuary, so a significant sedimentation process might help.

Jerry

[Rob 3,152]

The water runs off the grit which is covered in peat on the hills above the limestone. The peat is acidic, which is the reason the caves are formed when the limestone dissolves. The water throughput is such that it remains slightly acidic. If it was percolating through the limestone for years before it resurfaced it would be fully neutralised, but in this case dye tests give a transit time measured in hours from the bottom of Gaping Gill through to Ingleborough Cave.

Edited to add that the pool shown looks to be stagnant, so would only be refreshed with acidic water if that section flooded.

Edited September 24, 2015 by Rob