Using the Ferm Coding System
The Ferm coding system is a shorthand notation for recording the properties discussed on this website. Using the numbers, rather than the English words, saves time and facilitates data entry and analysis. The codes are logically assigned, so learning the system is relatively easy after a brief period of use. Example codes are provided for reference throughout the website.
A rock type is identified by answering a sequence of questions directed at determining rock properties. The code is designed to lead you through those questions. For example:
Digit 1: What is the major rock group?
Decimal digit: Is this a particular type of sedimentary structure?
In cases where a property is unknown or uncertain, enter “0” for that digit. For example, “501” denotes a crossbedded sandstone whose sand composition is unknown or uncertain.