What is this white stuff>

[Argyll]

I'm currently digging out foundations for my new shed and I've hit some white wet crumbly stuff. I've no idea what it is and not sure if it's natural or something the builders in 1955 dumped in my garden.

Any ideas?

[arco_iris]

or something the builders in 1955 dumped in my garden.

Could it be lime, or waste lime mortar?

[dewaltdisney]

I think you should keep it well wetted down just in case but I also think Arco is right.

DWD

[arco_iris]

(Untested surmise) try putting a teaspoonful of the white stuff into a bottle top/jar lid and add a splash of vinegar (acetic acid). Watch and listen - alkaline lime will fizz in the acid.

(Tongue in cheek) if it starts giving off smoke & fumes, run like hell, it's unexploded ordnance!

[Bob225]

Chalk or someone had a bonfire years ago...…………….

or

its quick lime and its a shallow grave

[arco_iris]

its quick lime and its a shallow grave

Dig a bit deeper..........