The famous group known as the Mammoth grove of Calaveras in California, containing over 90 large trees, stands in 38° N., about 4,370 ft. above the sea, between the San Antonio and Stanislaus rivers. It was discovered by A. T. Dowd, a hunter of Murphy's Camp, in 1853. The tree was made known to science by W. Lobb, who sent specimens to John Lindley in England. Some trees in the Mariposa grove rival these in size : one meas ures no less than lot ft. round the root, and a cut stump is 31 ft. in diameter.
The longevity of the big trees is very great. A tree under i,000 years of age may be regarded as still youthful. Huntington counted the annual rings of woody growth in 79 trees each of which was more than 2,000 years old and four of them exceeded 3,00o years. The wood of both sequoias makes excellent lumber, especially that of the coast redwood. Because of this, the original forests of these magnificent trees have been very greatly depleted. In 1925 the total cut of redwood lumber in California and Oregon was 510,639,000 bd.ft., valued at the mill at $17,356,620.
In earlier geological times the sequoias occupied a far more important place in the vegetation of the earth than at present, and it is interesting to note that fossil cones, branches and leaves of these trees were known to science many years before the living species were discovered. Instead of being confined chiefly within
the limits of a single State they were once distributed over four continents. The most ancient positively identified sequoia was recently discovered in the Upper Jurassic of France. In Lower Cretaceous times sequoias were widespread in North America and Europe. In Tertiary times they were still more widely diffused, occurring in the Eocene flora of Great Britain and attaining their maximum development in the Miocene period. Fossiled trunks, 6 ft. to 10 ft. in diameter and 3o ft. high, still standing erect, in deposits in the Yellowstone region (Miocene), are scarcely distinguishable in the microscopical characters of the wood from the living species. During the glacial period the sequoias were exterminated except in the limited area in North America where they still persist.
See E. W. Berry, Tree Ancestors (Baltimore, 1923).