Posted: 26/04/2015 at 04:29
There are about 7000 soil types in the UK, most depending on the underlying geology, the geological processes that have formed the bedrock and what has grown there over millenia.
All established gardens will be anthrosols (anthro=human) or tecnosols (product of the various additions to the soil). The original soil will be described by looking at whether there are distinct horizons( layers) and the nature of the horizons, humic content, mineral content (eg Al, Fe), texture (gravel, sand, silt, clay), blockiness, angularity...
See USDA soil classification if you are interested. It can get quite complex. It's not an exact science, it's just a very useful way to characterise soils.
You could google McCaulay soil maps, soilscape.ukso maps or uk soil maps , check on google images too.. They are mainly for agriculture but for sub/urban land you'll get the gist from the surrounding rural data.
you could dig a pit or core at a nearby uninhabited area, to see if there are distinct horizons, examine the soil where a tree has been uprooted or where significant erosion or other process exposes a cross section of what's under there.Check old maps I did this at the nearby woods and later found it was planted over a filled in quarry.
Though the above isn't about our personal gardens the underlying geology does massively influence, nay define what we garden on and how we have to look after, feed, water, restructure and in some cases drain our soils.
You could ask a neighbour who gardens "what are you gardening on, clay, loam, sandy? Is it acid alkaline?"
Remove grits and larger aggregates.
Dampen it, squeeze into a ball. If it doesn't hold together it has a significant amount of sand.
Next try and pull and form a ribbon out of it, if you can it has a significant amount of clay.
You could then drop a bolus of soil in a column and see how the sediment settles.
WWCCSoils has some practical labs (and lectures) on soil science on youtube if you want to get technical.
It's international year of soils, there might be some public access lectures round your way.