TREES AS CALENDARS

Evening Post, Volume CVIII, Issue 138, 7 December 1929, Page 20

TREES AS CALENDARS

RINGS THAT REVEAL AGE

(Copyright.)

Growing trees in New Mexico deposit « ring for each year of their lives, and under a microscope each ring shows individual characteristics. Moreover, in trees that have grown in the same region and so have been subjected to the same cycle- of dry, normal, and moist years, the rings in different trees, deposited the same year, can be identified. Thus,,each tree is a calendar for its 'life span. Tree rings, by their character, even show the years of greatest sun-spot activity, so that the record, they write can bo tied on to a sort of celestial calendar. The life of one tree in New Mexico •will not span many centuries. But an old tree and a young one growing side ay side will record the same charactertic season, and the young- tree will carry on the record centuries after its older neighbour has fallen or has been cut for timber. By taking cross-sec-tions of both, trees, a perfect calendar can be constructed for approximately double the life-span of a single tree. Cross-sections or cores have been made from many old beams taken from ruined pueblos scattered over northern New Mexico, and their ring records have been pieced together with those from trees. In this way a perfect calendar has been extended backward without a break from to-day to 1260 A.D. The beams from Pueblo Bonito alone cover a period of 700 years. But between this series of rings and the modern series is a gap of unknown extent, but believed to be short. On the work of closing this gap present researches are being centred. In seeking to close the gap the scientists are faced with a task that calls for even greater ability as detectives than their past activities. During "the gap" the ancestors of the Hopi Indians lived in the open rather than in eaves and cliff dwellings. Consequently, beams of that period will have had no protection, and in most cases, reached hy the moisture from rain and snow, will have rotted away. The only chance of success is to discover a ruined pueblo of the period which was destroyed by fire either accidentally or by enemies. Charred beams will be preserved in spite of moisture, and even if they have been converted entirely to charcoal, the greatly-desired nag neazd «aa still be lead.