How do these change a word? I vaguely recall -ic is preferred as a noun, -al for an adjective. I haven’t been able to find a source on my own, as Google (at least my searching thereof) results are either too vague or related to computers.
An example sentence:
Volcanism is involved in the creation of geolog**-ic**/-cal features.
Does it make a difference?
Thanks,
Rhythm
In general both -ic and -al are used to form adjectives. In your example, both geologic and geological are adjectives based on the noun geology.
I don’t know of any rule where one or the other has any specific meaning.
For adjectives:
-ic: of, having to do with; like, having the nature if, characteristic of; produced by, caused by; producing, causing; consisting of, containing, forming; having, showing, affected by…
-al: of, like, or suitable for…
-ical: sometimes having special or differentiated meanings that the corresponding -ic forms do not have (e.g. economic/economical)…
For nouns, see your friendly neighborhood dictionary, whence the above came.