abstract Concern about accelerating human impact on Earth systems coincides with discussion of adding a new proposed geologic epoch that would document the Age of Humans. This research contributes a human-environment timeline prototype. Time-period classification provides academics and citizens alike with a common temporal reference frame for discussion and further investigation. A hierarchical human-environment timeline was built from analysis of entries in four geographic encyclopedias. Through grounded theory, an open-ended, qualitative analysis of dates identified important events in the human-environment relationship and major ideas that shaped environmental perception. The resulting timeline prototype features a typology of periods based on five relative timescales: lengthy Durations, Duration Revolutions, intermediate-scale Scenes, Scene Transitions, and shorter Intervals. Four long-term Durations emerge: Survival (2,598,050 to 318,050 BCE), Adaptation (318,050 to 4,050 BCE), Keystone (4,050 BCE to 1945 CE), and Acceleration (1945 CE –). The timeline provides a foundation for further scholarly analysis and thinking.