Page:Climatic Cycles and Tree-Growth - 1919.djvu/63

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49
COLLECTION OF SECTIONS.

No. 4 proved to have fairly large rings with 3 to 4 single ones missing and some hard to find, but the identification was easy and entirely satisfactory. No. 1, which was by this time recognized as the most difficult of the group, was reexamined in detail by comparison with No. 5, which proved difficult, with No. 2, which was somewhat better, but especially with No. 4, which proved to have the closest similarity, and all apparent errors were removed. It was very apt to drop out completely rings which were a little below the average. No. 5 seemed to have no tendency to subdue or drop rings. This, with its disclosures of the ring for 1915, showed the necessity of including younger trees in any new group to avoid mistakes in the outer slow-growing parts of the older trees. A comparison of the last 70 years' growth of sections 1 to 5 is given in figure 12. An illustration of "gross" rings is seen in the upper curve.

When the second subgroup was compared with the first, two complete omissions from No. 2 and the others of that first subgroup were discovered. This necessitated the complete renumbering of the first five sections.

The sections were measured at this stage of the dating process. The final renumbering was made after the 1919 trip, the purpose of which was settling the identity of a doubtful ring occasionally found between 1580 and 1581. The existence of this ring was established and the necessary corrections on the sections and in the tabular matter in this book have been made. All subsequent comparisons have verified this identification.

THE SEQUOIA JOURNEY OF 1918.

The visit to the Big Trees in 1918 was for the purpose of procuring material so that the tree-record from the 2,200 years already secured could be extended to 3,000 years. It was expected to do this without great difficulty, for Huntington had enumerated 3 trees over 3,000 years of age, and he had placed numbers on the tops of stumps so that these could be readily identified. Nevertheless, in consequence of the occasional absence of a number on the top of a large stump which had been counted by him, a little more care proved to be necessary than was anticipated.

After procuring an outfit in San Francisco, I selected Hume as a base and immediately went out on the log road to Camp 6, the old location of the groups obtained in 1915. All the stumps from which samples had been taken (including Nos. 1 to 15) were visited and each was marked with its respective number preceded by the letter D. This marking was done by a chisel, and the figures were usually about 4 inches in height. Placing the capital D before each number made it certain that no number would be accidentally read upside-down. Naturally the stumps from which samples have been taken show the large cut from center to outside, and there is no doubt about their