Geology hub
Time & Dating
How geologists build timelines: relative order from layers, and absolute ages from isotopes and exposure signals.
Subtopics
Relative dating
Superposition, cross-cutting, unconformities, and correlation—building the order of events.
Radiometric dating basics
Half-life, parent/daughter isotopes, closure temperature, and what an “age” actually means.
U-series & carbonates
Dating carbonates (caves, corals, travertine) and what can reset the clock.
Surface exposure dating
Cosmogenic nuclides and weathering signals—how long a surface has been exposed.