A. E. Douglass Climatic Cycles and Tree-Growth

Annotation

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. Before taking up the details of collection and measurement it is desirable to describe certain preliminary studies, such as those upon the yearly identity of the rings, time of the year of ring formation, and so forth. These studies were made chiefly upon the yellow pine of northern Arizona, but from the Similarity between the pine and the other trees used it seems safe to say that the results apply equally to the Scotch pine, sequoia, hemlock and other species employed. Location. - The yellow pines upon which the studies were made were obtained near Flagstaff, in the central part of northern Arizona, at an elevation of about feet above the sea. The northern part of the State is largely a plateau forming the southern extension of the great Colorado Plateau. This high area is intersected some 65 miles north of Flagstaff by the Grand Canyon of the Colorado River. South of the town the high elevation extends 50 to 75 miles, varying only a few hundred feet from place to place, and then falls away abruptly at the Rim. Oak Creek Canyon begins some 10 miles south of Flag staff and flows to the south into the Verde River. The general drainage nearer town is gently to the northeast into the Little Colorado River some 40 miles away. Ten miles north of town the plateau culminates in the San Francisco Peaks, which reach an elevation of feet. This mountain is a finely shaped volcanic mass with the old crater breaking away into a canyon toward the northeast. The town is in latitude 35(deg) N. And longitude 113(deg) W. And lies between two ancient lava streams 200 to 400 feet in height. It has a wash flowing through it from north to south, but this carries water only in time of severe storm or of rapidly melting snow.