What's your soil like?

[MattyB]

They're building a house across the street and today they had a huge excavator with a breaker bar jack hammering out a hole for the septic tank.  An excavator that size could probably dig this 8' deep hole in regular dirt in about a half hour but it took them 12 hours to break through our Santiago Peak formation metavolcanic rock.  I always wonder what's going on down below the soil and this gives us a rare peak down inside.  The part that looks like a good 18"-24" of top soil is actually fill dirt from the slope they formed while creating the pad for the house.  Actual top soil is hard to come by here on Dictionary Hill and is usually somewhere between 2"-12".  Unlike most soils here in CA that get heavier, more compacted, and drain poorly the deeper you go, here on Dictionary Hill the deeper you go the less moisture the "soil", or rock in this case, can hold.  Palms love this as long as you can mulch heavy and get them enough water.  Very similar idea to the volcanic rock that they plant in on the Big Island of Hawaii but we just don't have the rain to keep plants happy so lots of supplimental irrigation is required. 

Anyway, just thought I'd share.  Can you guys show some pics of your soil?  I remember Kris shared some pics of his clayee in India and Ken Johnson has given us a glimpse at his solid limestone farm.  I'd love to see more of that sort of stuff. Peace.

Edited May 12, 2018 by MattyB

[yachtingone]

Many decades ago I had a leach line 17 feet deep installed in my back yard.  The first 5 foot is orangeish sandy loam. The next 2 foot was mostly gravel mixed with soil.  Bellow that all the way down to 17 foot is sandy loam.

Randy

[kinzyjr]

Dark, rich, and easy to dig:

 

[Mandrew968]

I am sitting on straight macaroni and cheese; oolitic limestone-25 feet deep or more, of it. 

[tropicbreeze]

I had a waterbore put in a couple of years ago, went down to 60 metres. Samples were taken at 3 metre intervals and I took photos of each plus bagged up part of each sample. The bore report listed the profile as:
0 to 3 m Top soil,
3 to 9 m Brown clay,
9 to 32 m Siltstone,
32 to 60 m Broken shale.

Of course their definition of "Top soil" is the first layer of relatively homogeneous soil. In agricultural terms the top soil there would only be about 1 to 2 cms deep, at most.

Later I had a pit excavated about 40 metres from the bore, down to about 2 metres. The top quarter metre was a fine sand and lateritic gravel. After that was soft lateritic rock, descending into hard lateritic rock.  The first metre went reasonably easily, the next put a real strain on the excavator.

There's also areas of red/brown clay mixed with small lateritic gravel containing large pockets of a white clay. Further along is a wide band of shattered quartzite with a little red/brown clay, not sure what depth it goes to.

Finally the back part of my land is a fine sandy/clay silt. It's waterlogged the whole wet season usually with shallow standing surface water. Dry season it turns to concrete.

The Agricultural Department told me the soil was notorious here. If you didn't like what you were on, just move a few metres along and the soil will be completely different. It was ideal for Mangos but not much else.