Replies

1. 
   oldhand | Jan 07, 2013 06:40pm | #1

   I forget but...

   Seems like in geology it refers to some soil types with limestone deposits of recent origin or some such thing.

   I do think your regional definition is indeed regional, like the highly technical term "blue gravel" used hereabouts.

2. 
   DanH | Jan 08, 2013 07:34am | #2

   I encountered it in Mexico some years back, and there it referred to a "soil" that resembled finely crushed (maybe 1-2" screen) limestone with the "fines".  Aside from it's lack (in the area where I was) of large aggregate, it would make an excellent "road base" or whatever -- it compacts well and seemed to have plenty of fractured surface (for reasons I don't understand).

   In any event, digging through the stuff required a pickaxe -- A shovel tip would penetrate maybe an inch.

   I've never encountered anything similar in Kentucky or Minnesota, and I doubt that it's common outside of the Southwest.

1. 
   JimB | Jan 08, 2013 05:01pm | #3

   In soil taxonomy, caliche is an aridisol, meaning

   that it forms in arid or semi-arid regions (hence, you won't find it in most parts of US).  I believe that it forms when calcium carbonate cements together gravel and soil particles into what is basically a sedimentary rock.

1. 
   tomask | Jan 09, 2013 09:20am | #4

   Geologist....

   ...here.  Caliche in soil science terms means a limy evaporative deposit formed in the soil profile by the evaporation of mineral rich groundwater, which leaves behind it's load of minerals, similar to lime scale in pipes.  It only occurs in arid regions where evaporation exceeds rainfall, such as the SW US and parts of Mexico.  It can be many feet thick.

   In construction terms, at least here in central TX, caliche is more of a catch-all term for any lime rich base used in road and pad building, such as true caliche or decomposed limestone.  The best material usually has some clay content and angular rock fragments, as someone mentioned.

1. 
   JimB | Jan 11, 2013 06:43am | #5

   Thanks for posting the follow additional info, which I was too

   lazy to look up.  It's amazing the breadth of knowledge that you see on this forum.

3. 
   Mongo | Jan 11, 2013 10:10am | #6

   Had it in Tucson

   When I lived in AZ it was a common term. Yup, a pain to dig through.

4. 
   gtmtx | Jan 13, 2013 01:15am | #7

   Thanks for the feedback, pretty much what I thought.  I was looking for "stone dust" here in Houston and when I asked a few supply yards they looked at me as if I was speaking a foreign language.  There are certainly regional terms.

1. 
   DanH | Jan 13, 2013 08:27am | #8

   I think "stone dust" is a

   I think "stone dust" is a pretty common term -- EXCEPT in that part of the country, where caliche serves the same purpose and can often be dug from your back yard.