UKC

As a non-chemist, I'm curious as to why the limestone at Swanage and Portland feels 'soapy' in certain conditions. I don't think I just mean greasy, as I think I even felt a soapy taste in my mouth after wiping it with my hand yesterday. I don't think I've felt the same soapiness at Pembroke, or on inland limestone.

In reply to kmsands:

Mixture of clay and seagull shit! A lot of the tops there have a thick layer of clay and soil which can make some Swanage top outs 'interesting' .

In reply to kmsands:

Not sure how relevant that is to the areas mentioned, but up here in Aberdeen conditions are very wind direction dependant. With most cliffs facing south and east, any wind from those directions has a tendency to blow moisture from the sea onto the rock. It can look dry, but feel like anything between grabbing a dry bar of soap and sopping wet. Northerlies and westerlies blowing from inland are most favourable. Maybe something like that at work here?

In reply to kmsands:

I've always assumed it's to do with the salt water spraying on and evaporating off, leaving salt behind, which then becomes slick from the moisture and heat from the air and your hands.

In reply to kmsands:

We found a tree in a forest producing soap bubbles as rainwater ran down it this summer, photo below.

It turns out it’s not really a tree thing, the tree is just the substrate that accumulated particles from the air in dry times and then mixes them with rainwater to make soap.  The texture of the bark seemed really good for this; perhaps some fluety limestone would do the same? 

https://bygl.osu.edu/node/1595

In reply to JimR:

Did you mention the seagull shit because I mentioned wiping my mouth with my hand?

You might be right but this was at Subluminal Cliff, which has a solid limestone topout and was guano-free. A sunny but windy day, after rain in the night, with a big swell and a bit of spray up to the lower ledge. I'm interested in whether it's a chemical reaction - it's doesn't feel like just a sheen of moisture, feels like it's sweated from the rock somehow and with a definite soapy taste and feel.

In reply to wintertree:

The regular bubbles suggests some creature at work there; like 'cuckoo spit'. But I guess a regular drip, drip, drip could do the same.

Plenty of tree and plant leaves contain saponins.

Not sure about the linked article: "soaps are a mixture of salts and acids'. Salts are the result of acid/alkali reactions. Soaps are fat/alkali products (that could still result from alkaline dust and fat/oil from a tree).

In reply to kmsands:

Maybe someone misunderstood the phrase 'cleaning the route'...?

In reply to captain paranoia:

If I could have posted a video I would.  You could see the bubbles forming dynamically in the down flowing water.

Yes, you need the fat from somewhere.  This happens on pines which aren’t saponin producers?  Really fascinating to watch it happen in person.

In reply to kmsands:

To clarify to the downvote squad, my reply to Jim, who I've climbed with, about wiping seagull shit on my face, was intended as jocular, rather than snappy. Hi Jim and thanks for the reply! I'm just not sure that explanation fits the particular cliff I was on.

In reply to Ciro:

The salt and maybe other things like alginate from seaweed while slightly damp I thought.  It’s definitely a real phenomenon on shaded limestone faces in Pembroke.

In reply to kmsands:

The clay/guano think is certainly pertinent on the Ruckle. However, oil is trapped in tiny bubbles in limestone and there are a couple of oil field extraction areas close by. Kimmeridge and Poole harbour . So I wonder if there is some sort of oil/calcium/ water mix going on when the conditions are spray and sunshine

In reply to carr0t:

Yes, the wind was certainly blowing right onto the cliff yesterday, and I'm sure it is something in the spray, but not just salt. I'm wondering if it is a reaction of salt water with the limestone itself (and/or oil, or something else organic in the rock or the water, as suggested in a few posts above)

In reply to kmsands:

In my professional opinion as a extremely mediocre geologist...

It's not really anything to do with the rock (you get soapy conditions on pretty much any rock type) if it was a chemical reaction there wouldn't be much cliff left the amount of times you get soapy conditions! It also isn't oil, you can pretty much always smell any hydrocarbons (and get obviouse staining). Try give the cliffs around Kimmeridge a good bash to get a fresh surface and give it a sniff.

What it is I rekon is simply salty water blowing onto the cliffs, salt is strongly polar and will attract water, (why salty water will rot fabrics, wood and ruin electonics). So it needs 'extra' drying when compared to plain old normal water by strong sunlight, a stiff breeze or low humidity.

In reply to kmsands:

Good question, and I know what you mean.

Ogmore has similar, smooth yellow limestone and feels the same on a bad day. The iron hard Pembroke/Gower stuff behaves like a completely different rock, climbable in heat or rain.

Always found Cornish granite to feel slippery, even way above the sea at Bosigran. The white, Lundy granite however, is always rough and grippy to the touch.

Haven't a clue why, unless it's simply down to texture.

In reply to kmsands:

It's definitely a thing in Pembroke too.

I'll throw in another guess... pH of seawater is a little above neutral, alkaline things feel soapy, maybe that's part of it 🤷

Edit: more likely just the amount of stuff dissolved in seawater getting more and more concentrated as it dries out. It's not like a drenching with pure distilled rain. 

In reply to kmsands:

Aye, if it's blow on it's just smegginess I would say. We've got the same up here pretty much. I'm sure there is chemistry in there somewhere, but whether it's a relevant to the feel of the rock I'm not sure. 

In reply to kmsands:

It's the same on the West Cornwall granite until the sun dries it. I think it's the salt retaining moisture

In reply to Steve Woollard:

I remember early starts often being a tactical error on Cornish granite ☹️.

Can't remember whether the greenstone gets similarly affected - or maybe I (without planning) never climbed on it in the morning.

In reply to kmsands:

Thanks for the various answers all. Seem to be a few possibilities but evaporating seawater leaving a moist residue which has salt & some kind of oily/organic matter in it looks most likely, and probably not a reaction with the limestone itself.

In reply to kmsandsY

Yes after rain Swanage limestone is extremly soapy. The short answer is that limestone disolves in water. Thats why there are caves in limestone, caused by rivers running through the limestone disolving it as it goes. The dissolved limestone often gets redeposited in cracks and that is what forms flowstone like on Reptile Smile on Portland. The other benefit is that Swanage routes don't seem to polish up. The surface dissolves when it rains.

I've no idea if salt (or guano) makes this process faster - I suspect not as I've felt every hold on Elysium go soapy in the rain. The top of the route was as badly effected as the bottom.

In reply to kmsands: The salt crystals feel slippery.  

In reply to mutt:

Notwithstanding the downvote a small amount of googling reveals that limestone dissolves faster in the presence of environmental acid. Guano has a pH of 3.4 being uric acid and so can be reasonably expected to accelerate the dissolving of surface ledges. I can't see how this would account for soapiness on popular routes as the guano would be rubbed off in climbing. 

In reply to JimR:

There is no oil in the boulder ruckle strata. Oil extraction is from the oil that has settled onto a impermeable basin formed by the syncline that forms 750m below the valley between purbeck and kimmerage. The boulder ruckle formation is the high point and doesn't contain any oil 

Edit:depth of oil bearing strate for clarity

In reply to mutt:

Surely not at the sort of rate that we would be able to notice by touch - otherwise the routes wouldn't last very long.

There are plenty of examples of rain exposed limestone getting extremely polished. I think with sea cliffs the fact that they are getting battered by the elements helps reduce polish, but not by washing it away - more the abrasion of everything from particles of sand to boulders getting chucked around by the sea.

In reply to wbo2:

I sometimes find my hands feel sort of greasy after sea kayaking, which takes a bit of washing off.  Other times that doesn't happen, so I'm not sure it can be accounted for by just the salt. 

I wonder if it might be phytoplankton or something like that.  They're generally too small to be seen with the naked eye, perhaps the concentration of them on the surface of the water varies with weather, prevailing winds further out to sea or something like that.

In reply to Ciro:

In fact the routes don't last very long. A walk below boulder ruckle show many scars of fallen routes. They fall because the overhangs are separated by cracks from the rock above. Eventually the dissolving connections fail. 

Isis (VS 4c)Tatra (E1 5b)The Planet (E3 5c)Larus (reclimbed after 2008 rockfall) (E1 5b) to name a few. They are numerous.

In reply to Ciro:

And many limestone cliffs have decidedly spikey ledges. This is caused by water collecting in dimples and dissolving the dimple until it gets very deep. 

In reply to Ciro:

It's an interesting question, a quick Google suggests UK rates for limestone have been measured at 0.035mm per year. This is for Carboniferous limestone (at Swannage its slightly softer Cretaceous limestone) and for Derbyshire. This is a very small  amount, we are talking geological timescales rather than human ones here. Rates at Swannage will be faster I would have thought as its coastal, and the rock is softer. But either way I would be surprised if its enough to either cause a noticeable effect on polish or case significant erosion/rockfall. 

https://www.sciencedirect.com/science/article/pii/S0016787813001016

In reply to Ciro:

It's an interesting question, a quick Google suggests UK rates for limestone have been measured at 0.035mm per year. This is for Carboniferous limestone (at Swannage its slightly softer Cretaceous limestone) and for Derbyshire. This is a very small  amount, we are talking geological timescales rather than human ones here. Rates at Swannage will be faster I would have thought as its coastal, and the rock is softer. But either way I would be surprised if its enough to either cause a noticeable effect on polish or case significant erosion/rockfall. 

https://www.sciencedirect.com/science/article/pii/S0016787813001016

In reply to mutt:

Allothough clearly the result of chemical dissolution of the limestone, I think these features take thousands, or tens of thosands of years to form.

In reply to kmsands:

Probably a combination of things: condensation, salts holding water, damp dust/clay and a biological film that enjoys those conditions.

It happens on the inland Yorkshire magnesian limestone which is quite distinct from the other rocks mentioned and definitely not salt sprayed. Clay and microbes.

jk

In reply to mutt:

Indeed, but this is long, slow, continuous erosion that eventually reaches a spectacular tipping point; if the surface was dissolved by rain at a rate we could notice by touching the rock, surely the routes would be dissolving back into the cliff at a rate we could notice.

In reply to ebdon:

The dangers of google scholar... 

a study on a variety of different limestone's gives results in the same order of magnitude to the UK one I linked to above - from 4 to 40 mm per thousand years,    

https://pubs.geoscienceworld.org/gsa/geology/article/42/9/751/131612/Limest... 

by that rate I reckon give the crags a rest of about 100 years and you might see a notable impact on polish levels.  

In reply to ebdon:

sure but as abdon has pointed out these cracks have been forming for millions of years. The dissolution or dissolving  is definitely responsible  for some significant cliff collapsing. The entirety of larus slipped down one night and I was able to walk the route stepping on the chalked up holds. 

But as far as the soapiness goes how much dissolving is required to give that feeling? I suspect only a very small amount of solute is needed. 

I remind you that I am probably the only person in this discussion who has direct personal experience of this phenomenon on a route in the rain and I also have an msc in geophysics to boot. Not everything has to be complicated. 

In reply to kmsands: I'm qualified as a geologist (hard rock!) but have a lot of years experience working as a geophysicist if you want to throw titles around,  I'd say it's a few things.

1. As before, salt crystals are slippery.

2.  The stuff is also comparatively soft as a mineral, making it prone to polish.

Clay minerals will also be present in small amounts, and concentrations will vary with bedding.  Will clay rich layer be more prone to forming holds, be more resistant, but have a 'clay' smear on the top?

In reply to kmsands:

high humidity is noramlly a factor IMO. Sun normally sorts it out. For Swanage the best conditions Ive found are normally wind over the top of the crag, but if its 80+ humidity its still likely to be a bit damp IMO.

In reply to mutt:

Run that past me again, you think you're the only one here who's climbed soapy wet limestone?

I've climbed wet/damp/condensed/seeping limestone of just about every major variety that outcrops in the UK plus some more, above ground, below ground, coastal, inland, clean, dirty, dusty, salty, teeming with life, smothered in shit and of course caked in greasy damp climber's chalk...

Some of it gets a greasy film on it, some doesn't.

Generally, the harder, more massive the rock, the more weathered (sea, wind, rain, flowing water) and the less exposed to sunlight (less life), the grippier it tends to be when wet.

jk

In reply to jkarran:

its different, I have also climbed greasy limestone but this is a definate wet soapy feel that is like you've lathered up and are about to shave. 

In reply to mutt:

I think this thread is about the soapy stuff we've all climbed, not the unique one that only you have experienced...

In reply to mutt:

I’ve had a few close shaves on limestone 😀

In reply to Ciro

Read back the original message 

'I'm curious as to why the limestone at Swanage and Portland feels 'soapy' in certain conditions. I don't think I just mean greasy, as I think I even felt a soapy taste in my mouth after wiping it with my hand yesterday. I don't think I've felt the same soapiness at Pembroke, or on inland limestone.'

So no it is not greasy or soapy as experienced anywhere other than Swanage 

In reply to mutt:

Still pretty hilarious to claim you're the only one who's experienced it. What did you actually mean? Because loads of us have climbed at Swanage and experienced it. And sometimes, though perhaps less often, you do get a very similar feeling elsewhere.

In reply to mutt:

Conversely I have experienced far, far greasier conditions at Pembroke then I ever have at Swannage, I suspect this is due to a sampling bias effect of climbing there a lot more, in a wider range of conditions then I have at Swannage. 

In reply to mutt:

I understand the OP.

I've climbed extensively in Portland and Swanage, also a fair bit in Pembroke, quite a lot of limestone DWS in the med, and on all of them I've found that under certain conditions you get an extreme soapyness that isn't found on inland limestone.

I haven't been to the East coast Mallorca DWS venues in the springtime, but I understand that if you do, due to the angle of the rock and the sun, you'll find the soapiest limestone known to man.

I would hazard a guess that the OP has a selection bias having climbed more often in soapy conditions at Swanage than at any other sea cliff.

In reply to kmsands:

Let’s talk about sticky damp. I’ve never experienced this rare mythical condition although the closest was probably on Gymnic in a downpour when being young and foolish we decided we’d better do some climbing instead of going to the pub😀

In reply to ebdon:

Me too.  The worst I can remember was on Keelhaul at Bosherston Head, which just felt terrifying.