In the 1980s, Bob Raynolds was in the Himalaya, reading the rock record preserved in the foothills to learn how the mountains grew. Meanwhile, Kirk Johnson was studying the evolution of plants in western North America with a particular focus on the effects of the cataclysmic event that wiped out the dinosaurs at the end of the Cretaceous. As time passed, Kirk expanded his research efforts, joined the Denver Museum of Nature and Science, and traveled the globe learning more about the last days of the Cretaceous. Bob worked with oil exploration companies, moved to Denver, and maintained his interest in the geological record of mountain building.

These paths were set to converge as Bob studied the geological record of the Front Range of the Rocky Mountains in his backyard and realized that he needed to know more about the vegetation that mantled the ancient landscapes; at the same time, Kirk was burrowing deep in the trenches being dug for the new Denver airport and finding fossilized remains of rainforests. How many rainforests were there? How long did they persist in the Denver area? How old were they? Bob had some answers to Kirk's questions and Kirk had some answers to Bob's. As so often happens in scientific research, the whole can be greater than the sum of the parts when the parts are effectively merged.

Later, as Kirk and Bob developed the research program that would help them jointly answer questions about the Denver Basin, they realized that the same rocks they were studying contain the water resources being used by the residents of the rapidly growing area south of Denver. Stan Robson from the United States Geological Survey had spent many years working on the groundwater resources of the Denver area and was intrigued by the questions being posed by Kirk and Bob. He encouraged them to consider studying the groundwater aquifers and suddenly found himself on board the project coordinating the water research efforts.