hawlet] ARCHAEOLOGICAL SURVEY OF NORRIS BASIN 3@1 



stant water supply, their growth rate is influenced by the more con- 

 stant factors of soil and age; hence their records are of no use to the 

 dendrochronologist. The average precipitation for the South and 

 Middle West, so much above the averages for the Southwest, was 

 long the source of a fear that the ring record of trees from those 

 areas might show so little variation from year to year that no char- 

 acteristic pattern could be obtained from them. Without such a 

 characteristic pattern extending far enough into the past to overlap 

 the pattern of the mound specimens, dating would have been 

 impossible. 



Our first problem was to discover that the variations in annual 

 precipitation were sufficient to produce appreciable growth changes 

 and hence sensitive ring records in this area. Our second was to 

 learn which species of trees carried the records best for our purpose, 

 neither too complacent nor so sensitive as to be erratic. Our third 

 problem was to find whether these trees would cross date and hence 

 give a master chart for the area; and our fourth was to locate trees 

 of the requisite species with records extending far enough into the 

 past to pick up the records of wood from the mounds. 



The first, second, and fourth problems solved themselves together. 

 While a number of different species of trees — pine, oak, juniper, 

 hickory, gum, elm, maple, and cucumber — showed records of some 

 sensitivity, the best records were found to be carried by those trees 

 which likewise carried the longest records : the oaks and the junipers. 

 The white oak (Quercus alba), the eastern red cedar {Juniperus 

 virginiana) , and the southern white cedar (Chamaeocy parts thyoides) 

 carry records sensitive to annual precipitation changes and yet grow 

 slowly enough to provide long ring sequences. Moreover, oak and 

 red cedar are the two species of wood most commonly found as char- 

 coal or as partially decayed posts in the mounds. As the oaks were 

 the least prevalent of the three it was decided to concentrate for the 

 present upon the study of the junipers. 



Junipers have never been used to any extent for southwestern 

 dating, as their habitat of poor soil and relatively low altitude, about 

 4.000 feet, makes their records tend toward being erratic and full of 

 double or false rings. As the yellow pine (Pinus ponder osa) , grow- 

 ing in higher altitudes and providing records much better for tree 

 ring analysis, was largely used for beams of the ancient pueblos, pine 

 has been taken as the foundation of the tree-ring studies for the 

 Southwest pueblo area. Its close relatives, the pifions and the 

 Douglas fir, are also used. 



In the southeastern part of the United States the junipers grow 

 at lower altitudes and in a climate sufficiently humid to provide ring 

 records which are sensitive but much less erratic than those of west- 

 ern specimens. Nevertheless, the southern cedars are still more dim- 



