2 spades deep is hard digging FB. 3 or 4 Spades deep is for ponds and coal mining.

You've lost me.

You don't need to dig more than two spades deep Funguy. Anything that puts roots down deeper than that will cope with whatever it finds.

The reason i went down that deep was to remove large pine roots, as i had two pine trees removed from my garden with the stumps left in the ground and couldn't dig the beds properly, so i excavated the roots.
I am not suggesting it needs to be dug out or that i am going to dig it out(but when i was down there i removed a bit of it - large chunks of this black stuff).

You are on my Hero list.

I am wondering if it could be an iron-pan or a layer of carboniferous material. The only concern that I would have is if it affects the drainage of the soil in your garden. If you want to know exactly what it is ask your local agricultural college. This pan will cover a wide area of ground and their soil maps should have a record of it.

Yes an iron pan Bulbaholic. On a websearch it said -

'• Cementation - in certain cases, a subsoil iron 'pan' or hard ferrous layer can form, effectively preventing root penetration. Iron pans can be surprisingly hard, and if dug out can be held up and may need to be 'snapped' to break them!'

I'm pretty sure that is what it is, as it ties in with the soil map of the area.

The stuff that is in my garden is not very hard, and the drainage is good,so i hope it is not a problem. I wonder if it will disperse by improving the top layer of soil and also wonder if the iron in the iron pan affects the top soil and its levels of iron/nutrient.

Pimpernel, do you have a 'bright as a two-watt bulb list'? I'd feel more at home there.

Welcome to my world..

Fungay I really appreciate your humour and will leave my SO Bulba. to discuss iron pans with you... just don't hit anyone over the head with one!

'Toc H' lamp?
If you have poor drainage, Funguy, then the pan would need to be broken to improve this.

I'm glad Moongrower, just wish my OH was into gardening. Can't imagine what turns her off.

we have a saying ' as dim as 2 Toc H lamps wired in series.' along similar lines me thinks :o)

Improving the top layers wont break up the iron pan.
I cant remember the science behind the formation. I covered that at uni back in the 70's. [must go back and re read it.]

The black sounds like the remains of a fire to me. If it was heath land before being your garden - a long time ago - it could be the remains of one, or several gorse fires.

If it's that far down it probably isn't a problem

At whatever point in in geologic time that layer once saw daylight, surface and immediate subsurface conditions could have been extremely wet for a prolonged period of time, a perfect environment for anaerobic microorganisms. These anaerobes utilize sulfur instead of oxygen in their metabolic processes, the end product being hydrogen sulfide. Example: pull out a plant in a pot without drainage holes in it and you will get a good whiff of the hydrogen sulfide(H2S) produced by this form of life (the rotten egg smell). H2S is extremely reactive with metals in the soil and will form metallic sulfides, the black particles of which compose the appearance of the black layer mentioned. This layer has the potential to be impervious to roots, be toxic and cause poor drainage but in the case mentioned, it's far enough below the surface to be any cause for concern for most garden plantings
and projects. The possibility of an ash layer was
mentioned; soil analysis for the presence of charcoal
would affirm this idea.

I've never seen a black iron pan.
Mmmm..
In a soil profile, I mean. Aren't they normally rusty red/brown? Makes me think this is something different, as others are suggesting.

Bulbaholic your term 'Toc H' lamp takes me back to when I was an apprentice as one of the chaps used this term regularly. Haven't heard it again until now. Nice one!

You must be of similar age and background to me, Jimmy. That is how I first became familiar with the term. Not something that I use everyday, mind!!!

Thanks Bulbaholic, no drainage problems so no need to break it thanks for your advise. And after a search i now know what a t-hoc lamp is and was used for! Seaburngirl, i like your original version, better than the two watt bulb! Very good.

Obijway, thanks, i have internet searched - (originally 'iron pan' which resulted in a plethora of kitchen products, mainly 'le creuset', nice pans as it goes!) and the main results for an 'iron soil pan' show the colours you have mentioned.

So yes Beattie, i guess it could/possible is carbon material from a past fire. As you mentioned in your first post Bulbaholic

I have learnt a lot, and your answer Eclectic, is very informative.
Thanks all, for your responses.