In a way that relates to or is based on geology, the study of Earth's rocks and structure.
From geological (adjective) + -ly (adverb suffix). Geological itself comes from geology (Greek geo- 'earth' + -logia 'study'), forming the adjective with -ical in the 18th century.
When scientists say something is 'geologically young,' they might mean a rock formation that's only 50 million years old—a humbling reminder that Earth's timescale is almost incomprehensibly vast!
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