UKH

I've searched the whole web for the answer to this one without much joy so will be grateful for any info anyone can contribute.

What I'm trying to find out is; if I am on a glacier in August or September and there is no loose snow and the surface of the glacier is like the other neve, (currently scalloped, wind blown, melted, re-frozen and firm), and I can clearly see some crevasses (sometimes only 10cms wide) in some places, can I be confident that ALL the crevasses are visible?

Just for context , I live in the French alps and have been going for some nice long day walks here and there for the last few years. I'm retired and totally out of date and practice with actual climbing (bar the odd scramble to a rocky peak) though I used to do a bit of climbing and caving back in the 1970's.

Any thoughts besides the usual advice of roping up, crevasse rescue etc on which much has been written?

No-one will give you an absolute guarantee on that matter.

No, you cannot be confident that all crevasses are visible.

Are you sure?  I think pretty much every discussion of glacier travel highlights the risk of concealed crevasses.  You most certainly can't assume that because you can see some crevasses you can see them all, rather the reverse if anything.  The fact you are walking on neve rather than fresh snow doesn't change this.  Even on a dry glacier there is some risk.  Whether you take the risk  of walking on a glacier unroped is up to you - no one can else can decide.

If there's snow on the surface, no, you can't be confident that there are no hidden crevasses.

If there's no snow on the surface (i.e. it's glacier ice) then you can be confident you can see all the crevasses.

If you're not sure whether it's snow or glacier ice, presume there is snow. 

(You'll see people refer to this as wet and dry, which boils my piss because it is incredibly wrong). 

Err why? Wet/dry used metaphorically of course. What would you say?

Snow covered and snow-free. Every glacier in the entire world is wet in the sense that they all have some liquid water at the surface - even when not apparently melting there is very small amounts between ice/snow crystals. Conversely, the "dry" mountaineering definition actually tends to align with the wettest bits of glacier - i.e. those with a melting surface and lots of surface meltwater. Wet/dry is also used crudely to describe the presence or lack of water at the bed. 

For context, I'm a glaciologist by trade - my job is in a university and my research area is glacier surface hydrology. 

If you are walking on a dry glacier, you will find it difficult to arrest a fall, and if roped, one falling person might pull the rest of the party with dire consequences for all.

I don't think anyone takes the terms literally, they are just useful shorthand.

https://www.ukclimbing.com/articles/skills/series/alpine_skills/glacial_tra...

Thanks for your reply.

I think it's maybe walking on firm neve where what's under foot looks identical to shallower, non-permanent neve that gives one a false sense of security. There is indeed a lot of stuff on the web about crevasses but the terms wet and dry are used a lot as if there are two binary conditions one can detect and choose a strategy accordingly. The reality might be more complex.

Thanks to all who have contributed to my question. Together you've given me as good an answer as I think it's possible to get. These 'hidden dangers' are always a tricky and emotive subject and naturally it's always good to err on the side of caution. But sometimes we also take risks and the more we know about how to evaluate them the better.