Sunday, August 15, 2010

Definitions are funny

I wanted to talk about the difference between soil and rocks, but when I started looking up definitions, I remembered that there isn't a singular definition on which we all agree for these things.  The definition of a word depends on who you talk to, and the definitions bleed into one another.  

For example, I happened upon the knowledge that the classic definition of geology is the study of the earth

The study. 
Of the earth.  (Doesn't that kinda mean everything? Doesn't the study of the earth also mean economics and anthropology and religion?)
And its life forms, and the evolution of life.  
Which now sounds more like biology.  

To be honest, I like this definition.  Cuz I think that geology does include the study life and its evolution (for example, paleontology), but only as it has been recorded in the rock record.  But what are rocks?

Please click here for the definition of "rock, " courtesy of the US Geological Survey (USGS).  Notice they use the word "mineral."  What are those?

Please read the definition "mineral,"  by the Soil Science Society of America (SSSA)- "a naturally occurring homogeneous solid, inorganically formed, with a definite chemical composition and an ordered atomic arrangement."  

Oh, but no! The USGS begs to differ.  They are more specific than the SSSA's "homogeneous solid," calling it an element or compound instead.  I like this better.  Also, "the ordered atomic arrangement" is called a "crystal form" by the USGS.   Same difference.

I know.  Tedious.

Anyways, here are soil definitions, courtesy of the NRCS.

Here is some mica.  Common in the Glenelg silt loam in Maryland.  Use fingerprints for scale.
What I get, is that soil has rocks in it, but soil is also an ecosystem.  There is air, liquids, and solids in soil.  There is water, there are minerals.  There is representation from all taxonomic kingdoms of life.  Oh and look, there is also my heart and soul (transcendent violins, please! And an angelic chorus).  

1 comment:

  1. I like your commentary on definitions. It really depends on what you're talking about or to whom. Are the minerals defined in the periodic table of elements or something similar?