geological
adj.relating to the study of the Earth's rocks, layers, and how they change over time. You use this to describe things that happen over millions of years.
adj.relating to the study of the Earth's physical structure and substance. Often used to describe processes or time scales that occur over extremely long periods.
“The Grand Canyon shows many geological layers.”
“Scientists use geological evidence from deep ice cores to understand how the planet's climate changed thousands of years ago.”
“The region's unique geological history, marked by volcanic activity and tectonic shifts, created a landscape that is both beautiful and dangerous for modern infrastructure projects.”
Typically precedes the noun it modifies; often used in the phrase 'geological time' to contrast with human history.
Usage geological evidence
“This famous geological formation preserves fossils from near the end of the age of dinosaurs.”
“The US Geological Survey said the quake hit Indonesia’s Flores region with a depth of 10 kilometres at 5.58am local time.”
Common in science writing
From Renaissance Latin geōlogia + -ical; first attested slightly earlier than geology. By surface analysis, geo- + -logical.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.