"Janet Baraclough.." wrote in message
...

It might just be an old hedge, wall or tree line; can you see signs of
it continuing beyond your garden?

No, it only goes along part of the garden and levels off at the bed in front
of the shed.

I'd very carefully hand-dig an inspection hole to find out what's down
there. Until you know for sure, there's little point speculating about
levelling it. If your garden/house is modern, watch out for buried
colourful plastic tape, which is used as a warning to diggers that
there's something below to be careful of.

Alternatively you could try asking your council/longterm neighbours if
they have records/memories of underground works in your garden.

I spoke to the next door neighbour who said that the garden was dead level
until a few years ago!

I've had a dig down into the ridge and it appears to be just soil, which is
a relief. I've already had to shift a couple of tons of rubble that was
covered with a sprinkling of soil and cunningly disguised as a raised bed,
and removed the concrete foundations of a wall which had just been turfed
over.

I suspect that this ridge and the odd slopes are just the previous guy's
highly original idea of 'landscaping'. Guess I'll have to do some digging,
when I feel energetic enough!

thanks to jane and Janet