In my current home, I'm going to guess silt. That is assuming silt means organic as the soil of the area is very rich, moist, and smelly. I mentioned in another post that this is the fertile side of the mountain. :P

My childhood home, however, was clay, sand, and rock mixed together! It was at one point a river bed and before that it was the shore of an ocean. Trying to dig a post hole there was an hour of work and deposits of black dirt were precious and heavily guarded.

clay for sure.

Here, on natural soil for this area (Provo, Utah) it is a sandy loam. I live on the bottom end of an alluvial fan, so there is a lot of rock in the natural soil here. This valley is also the site of ancient lake Bonneville with the remnant being a large freshwater lake - Utah Lake. We have a lot of very silty soil nearer the lake. Clay isn't too bad, but it tends to be pretty hard when dry and some clays are vermiculites. I took 15 hours of soil science as an undergrad - environmental science major.

One way you can test your soil is to put an average sample in a clear cup. Add water, mix till it is a consistent slurry. Then, let sit without disturbing it. Once the water has gone mostly clear and the soils have settled, you can usually see pretty easily the thre kinds of soil - Clay, Sand, and Silt. You can find the percentage of the total volume each is and see the basic mixture you have.

You can also take a little soil in your hand, add a little water till you can form a ball with it and then press it between your thumb and forefinger. It will help you see the basic texture.

Typically, quaternary alluvial deposits here in Las Vegas. Very sandy, in isolated areas there is a high clay content

Sand on the flat areas, and decomposing and fractured hard rock exposed on hills and slopes. Observable in parks and backyards, especially near beaches.

right now, it's wood.
outside, rock

I live in an area where the was previous glacier activity. The soil under my feet consists of rock, clay, sand and soil - with almost consistent proportions.

This is a tricky question. Within the Helena Valley you can find all of these. However, we are truly in the Rocky Mountains and you will find lots of rock in the soil. In the lowest places in the valley there is lots of silt from past river action. There are some places with clay, as well, on the higher benches. Naturally, when you are close to the Missouri River you can find lots of sand. Glacial and river action on the land here gives us a wide variety of soil types.

clay

Clay.

I'm currently in the back bay of boston, which was reportedly mostly filled in. That, said, I have no idea with what.

Clay.

From long experience of adding soil amendments, like gypsum, bat guano and worm castings, steer manure, chicken manure, etc.

Some clay - some silt - mostly sandy loam from the riverbottom of the Willamette Valley.

Here in the Berkshires it's glacial till. Same when I lived near Squam Lake in NH.
The bedrock here is schist, probably close to a billion years old, in NH it was a younger schist, maybe 250 to 400 megayears. It started as mud and silt somewhere got made into rock miles underground. The glacial till came from rocks to the north so still made of ground up bits rock that started out as silt and mud in some Cambrian or Ordovician Sea.

Despite living in New England, famous for its rocky soils, I live on clay. This is becase my home is on the floor of glacial Lake Hitchcock, which stretched from the middle of Connecticut to northern Vermont as the last glaciation receeded. When the weight of the ice was was removed, the land rebounded, spilling the lake out as it tipped up. That was 12,000 years ago.

Melody again had a great suggestion. I am on a Mac so I haven't been able to test the version 1.0 of the web soil survey run by the government, here http://websoilsurvey.nrcs.usda.gov/app/ .

Does this work for others if you submit your local area?

Having dug the garden, and pulled stumps,
etc., it's sandy clay. Lots of rocks. Typical
glacial drumlin.

http://www.usgs.gov/
U.S. Geological Survey (I believe several other countries have their own G.S. site online)

Adobe clay is a big factor, but silt demarks the best agricultural land, here abouts. (Though much of the water remaining from the Tulare Lake bed is pretty ghastly for drinking purposes.

http://soils.usda.gov/survey/online_surveys/

1. Dig, dammit
2. Ask a gardening neighbour
3. Ask a local builder or plumber
4. Local garden centre

I live on rock. The reason I'm anywhere near 100 feet above sea-level is because I'm on a ridge above the coastal plain. I used to live in Bayonne, which is mostly clay. Used to have good water; that's long gone. Clay with rock; the King's Highway was built on a ridgeline 400 years ago. That ridgeline goes all the way to Rockland County, NY.

NGS is where I'd find out the exact nature of my geography.

mainly sand and limestone