From the Sinagua cliff dwellings that look out over the waters of Montezuma Well, one can observe a dramatic play, one which has been acted out over thousands of years. The cliff dwellings themselves date back to about 1050 CE, yet the springs, which pumps over 1.5 million gallons of water into the well each day, have existed for much longer; at least through the late Pleistocene Epoch (likely more than 100,000 years).
Montezuma Well, a collapsed carbonate mound limnocrene spring, is a case study of the way a springs ecosystem serves as an evolutionary theater. The ecological dramas that have played out in Montezuma Well in particular makes it extremely unique.
An isolated, long-term, stable ecosystem, Montezuma Well supports the highest concentration of unique species at any point within North America, to our knowledge. Where some springs support one to two unique species, Montezuma Well supports at least seven unique species including a water scorpion (Ranatra montezuma) and Hyalella montezuma, an amphipod characterized by its extended appendages, large mouthparts, and up to 30 plumose setae compared to the normal 2-3 within this genus. (Watkins and Cole 1977; Blinn 2008)
According to Dr. Larry Stevens (Director of SSI) and Jeri Ledbetter (Program Director), several factors contribute to the Well’s high levels of endemism. Specifically, the Well’s central location to the Verde River drainage system, its geographical layout (steep slopes) that prevents biological disturbance from flooding etc., it is uniformly warm, contains calcium-rich water, and the naturally high concentration of arsenic in the Well water all contribute to its highly dramatic and yet insular biodiversity.
More information on aridland springs can be found in Aridland Springs In North America; Ecology and Conservation, by Dr. Larry Stevens and Vicky J. Meretsky
Quote from the Publisher: “This volume is a must read for all who are interested in the oases or the future of water in the western states.” - Choice