World-power and evolution / by Ellsworth Huntington.

  • Ellsworth Huntington
Date:
1919
Catalogue details

Licence: In copyright

Credit: World-power and evolution / by Ellsworth Huntington. Source: Wellcome Collection.

    135/296 page 131
    of evidence indicate that this was a period of unusual climatic stress. (See Figure 24.) It was like a glacial period on a small scale, and like present periods of solar activity on a large scale. This was especially evident in the two storm belts. In the southern belt during the early part of the fourteenth century the Big Trees of California, as we know from the rings of their stumps, suddenly increased their rate of growth. They grew with a vigor un¬ equalled at any other time since about 1000 A. D. This means that the rainfall, especially in the late winter and spring, was at a maximum. Not far from the Big Trees, but on the opposite or eastern side of the Sierra Mountains, lies Owens Lake. This bod}7 of salt water now has no outlet, but formerly it overflowed. When the Owens River was diverted into the Los Angeles aqueduct to be carried two hundred and fifty miles across the mountains, both the lake and the river were most carefully measured and analysed. From the amount of salt in the two, Gale has calculated the length of time since the lake overflowed. This must have happened not long before the time of Christ. The climate must then have been so moist that the lake was two and a half times as large as at present. From this fact and from our knowledge of the Big Trees we can determine which of the various elevated beaches • surrounding the lake belongs to the fourteenth century. The beach thus determined appears to have been formed by waves of unusual intensity. This means that the storms of the early part of the fourteenth century were very violent. Far away in western Asia historic records show that at this same time the Caspian Sea rose rapidly to a level many feet above that of today and above the position it had previously held for several centuries. Still farther to the east in the very heart of Asia the desert lake of Lop-Nor in Chinese Turkestan likewise rose, and overwhelmed the “Dragon Town.” Thus at both ends of the southern storm belt we find signs of unusual storminess culminating about 1325 A. D., while other evidence indicates that similar conditions prevailed in the intervening portions.
    digitised image 1
    digitised image 2
    digitised image 3