Walk Through Time is a loop path built as a scale model of the most recent 600 million years of geologic time, where one foot represents one million years. Along the route, visitors can touch rocks from layers formed in environments where trilobites crawled, where a giant Devonian fish was buried, and where Triceratops and Tyrannosaurus rex lived. Beginning in 1998, more than 100 students from Broomfield Heights and Broomfield High School worked to create this outdoor science museum for Broomfield schools and the wider community on City of Broomfield Open Space as the first project of its kind in the community. The walk uses the geologic time scale after the Precambrian Era, dividing Earth history into periods defined by major geologic events and by fossils preserved in rock. It highlights the Permian Period, when amphibians dominated before drier conditions led to their decline and reptiles spread more widely, and the Cretaceous Period, associated with dinosaurs on land, chalk-forming sea life, and the beginning of Rocky Mountain uplift near its close. On the path's scale, modern human activity would occupy only about half an inch at the very end, underscoring how brief human history is compared with the age of the Earth.