Soil Series
When does a system of classification limit the imagination, and when is it liberating? Today in the course of reading about something else I stumbled upon the USDA classification system for soils, helpfully illustrated in a great poster:

As it turns out, the US Department of Agriculture maintains an entire taxonomy of soil types, not unlike the Linnean hierarchy for life. The soil version includes orders, groups, families, and finally the series. At the lowest level there are many, many series–perhaps not as many as there are living species, but still, for the majority of the population that has moved away from agricultural occupations, a staggering number of soils. From Wikipedia:
About 4,500 soil families are recognised in the United States…A family may contain several soil series which describe the physical location using the name of a prominent physical feature such as a river or town near where the soil sample was taken. An example would be Merrimac for the Merrimack River in New Hampshire. More than 14,000 soil series are recognised in the United States. This permits very specific descriptions of soils.
Take a look at the start to USDA’s description of the “San Joaquin” series:
The San Joaquin series consists of moderately deep to a duripan, well and moderately well drained soils that formed in alluvium derived from mixed but dominantly granitic rock sources. They are on undulating low terraces with slopes of 0 to 9 percent. The mean annual precipitation is about 15 inches and the mean annual temperature is about 61 degrees F.
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