RADIALS 19 



tree in the lava-bed near Flagstaff took nearly two hours of very hard 

 work. When it is needed, no doubt a suitable borer will be easy to 

 construct. 



FALLEN TREES 



The chief work on fallen trees was done in the Calaveras Grove of 

 sequoias. The bark of these trees lasts 10 years or so after the tree 

 has fallen. The sap wood weathers off in something over half a cen- 

 tury. Heartwood has lasted a hundred years in the open air, but in 

 the case examined the wood was badly decayed and little of it was 

 left, as shown in Plate 2. It has been a disappointment not to find 

 logs lasting far longer, for example, a thousand years; for if very 

 large ones could be found they might have very old ring records. 

 Apparently even the wonderful qualities of the sequoia sap will not 

 preserve the wood indefinitely. Fallen trees give the chance of boring 

 at any height and from that arose the vertical uniformity or "taper" 

 tests given below. 



In the Calaveras Grove there were three classes of fallen trees, 

 so far as dated records were concerned: (1) old tree- trunks without 

 sapwood, so that the date was unknown; (2) trees showing sap wood, 

 with approximate date of falling; and (3) those whose date of recent 

 f ailing was known. So to insure correct dating, all three were included. 

 Thus an overlapping group was obtained, which by cross-identification 

 produced correct dating for the Calaveras trees. But all this care 

 proved unnecessary, for the first radial examined, as well as all the 

 rest, readily dated in terms of the trees in the southern groves. 



STUMPS 



Collection from stumps permits many forms of which the full 

 section is only possible in the case of small trees. Thus full sections 

 have come from the white pines of the American Arctic and from the 

 beams of the ancient ruins. At the start, full sections were made of 

 the early Arizona yellow pines, but they have proved so unwieldy 

 and difficult to provide space for that even from these radial samples 

 have been cut, which give the ring sequence from center to outside. 

 So methods of collection necessarily adapt themselves to the size of 

 the trees. In the vast majority of cases a piece is cut from the stump, 

 and that process is described below. 



Shape of stump — In felling a tree a notch is first cut on the side 

 toward which the tree leans and will fall. This undercut goes perhaps 

 one-fourth way through. In big trees it becomes large enough for 

 men to stand up in. Then a two-man saw is started in horizontally 

 from the opposite side at a slightly higher level. As the saw enters the 

 tree, the weight of the tree will pull away from it and not make it 

 bind. Sometimes the tree is leaning so heavily that as the saw gets 



