The Classic Period came to an end shortly before A.D. 1300 when the Indians abandoned their homes in the Mesa Verde and moved away. We can only guess the reasons for such a move. One suggestion is that the great drouth, which lasted from A.D. 1276 to A.D. 1299, caused them to leave. Another suggestion is that this was a period of strife either between the villages themselves or between these village people and nomadic groups moving into the area. Whatever the reasons, the cliff dwellings of the Mesa Verde were empty by A.D. 1300. It was a rancher from Mancos, named Richard Wetherill, who first discovered Spruce Tree House—on December 18, 1888. He and his brother-in-law, Charley Mason, also discovered Cliff Palace that same day. The men had been looking for lost cattle when they first saw the cliff ruins. [Illustration: _Spruce Tree ruin before excavation._] [Illustration: _And the ruin after excavation and stabilization._] In 1906 Mesa Verde was set aside as a National Park by Act of Congress to protect and preserve these dwellings of the prehistoric Indians. In 1908 Dr. Jesse Walter Fewkes of the Smithsonian Institution excavated Spruce Tree House. He removed the debris of fallen walls and collapsed roofs and stabilized the dwellings more or less as you see them now. It has been necessary, of course, to further stabilize the walls from time to time, but aside from minor repairs and the roofing of the three kivas, the dwelling is original work done by the Indians some 700 to 800 years ago. The dating of Spruce Tree House and other ruins in the Mesa Verde has been done by the study of tree-rings from original roofing timbers. If you are interested in how archæologists determine the dates, see the exhibit on tree-ring dating in the museum. This trail guide booklet is not a government publication and is not included in your fee to enter Mesa Verde National Park. It is published and sold by the Mesa Verde Museum Association, a non-profit organization, whose aims are to help in the understanding and interpretation of the park story. Your comments and suggestions concerning this booklet will be appreciated. CONSERVATION—YOU CAN HELP If you are interested in the work of the National Park Service, and in the cause of conservation in general, you can give active expression of this interest, and lend support by alining yourself with one of the numerous conservation organizations which act as spokesman for those who wish our scenic and historic heritage to be kept unimpaired “for the enjoyment of future generations.” Names and addresses of conservation organizations may be obtained at the Information Desk. MISSION 66