shale
UK[ʃeɪl]US[ʃeɪl]
n
A type of soft, fine-grained sedimentary rock that splits easily into thin layers.
Etymology
The word 'shale' originates from the Old English term 'scealu', which primarily meant a shell or husk. This connection is logical, as shale rock often has a flaky, layered structure that can resemble the thin, brittle layers of a shell. The term evolved through Middle English as 'schale', retaining its core sense of a thin, separable layer, before solidifying into its modern geological meaning. The semantic journey, therefore, is from a general concept of a thin, hard covering to the specific, layered rock type we identify today.
Analysis
The word 'shale' is a simplex word of Old English origin. It is not productively composed of smaller, meaningful morphemes in modern English.
Examples
The geologist extracted a sample of dark gray shale from the cliff face.
Shale formations often contain deposits of natural gas and oil.
The path was covered in loose shale that crunched underfoot.