between AD 1276 and 1299, a period of time that is now referred to as the "Great Drought". With the limited amount of rainfall in an already arid environment, there is no doubt that there was a considerable amount of increased stress put on the agricultural systems that these people depended on. There is evidence later in the record to suggest the beginning of an episode of deep arroyo cutting, that would have damaged what was left of the usable agricultural land. Increased deposition of sediment onto agricultural lands caused the lowering of the water table, thus making the land inadequate for farming. Regardless of their reasoning, near the end of the thirteenth century it's evident that the Ancestral Pueblo people migrated towards places with more stable and abundant water sources, suggesting that the agricultural land in this area had become unsuitable to sustain the population levels that once inhabited this spectacular cave site. Hopi legends tell a different tale. According to oral tradition, the area known as Wunuqa (modern day Tsegi Canyon) was abandoned as part of a spiritual quest. In particular, the Snake Clan inhabited the Navajo National Monument ruins, along with the Horn Clan. The Horn Clan forced the Snake Clan out, due to the children of the Snake Clan biting other children and causing death. This may be an allegory for some historical occurrence, in which one group forced another out for a perceived fault or slight. Climate Navajo National Monument has a cold semi-arid climate (Köppen: BSk) with cold winters and hot summers. See also List of national monuments of the United States Canyon de Chelly National Monument Mesa Verde National Park Oasisamerica cultures References Related Readings Doyel, David E. & Dean, Jeffrey S. "Environmental Change and Human Adaptation in the Ancient American Southwest". The University of Utah Press, Salt Lake City. 1996 Ferguson W.M. & Rohn A.H. "Anasazi Ruins of the Southwest in Color". The University of New Mexico Press, Albuquerque. 1999 Noble, David Grant. "Houses Beneath the Rock: The Anasazi of Canyon de Chelly and Navajo National Monument". Ancient City Press, Santa Fe, New Mexico. 1986 Plog, Stephen. "Ancient Peoples of the American Southwest". Thames & Hudson Inc., 500 Fifth Avenue, New York, New York 10110. 1997 Rothman, Hal. "Navajo National Monument: A Place and Its People". Southwest Cultural Resources Center. Santa Fe, New Mexico. Professional Papers No. 40, 1991 External links NPS: