THERMAL LIMITS OF PHYSICAL PHENOMENA, SNOW-LINE AND
GLACIERS.
Physical geography presents many phenomena which, though not exclusively
dependent upon temperature, show so decided a connection with it, that in order to
complete the researches concerning its distribution in different provinces and at various
heights, a comparison with at least some of the principal features has to be taken into
analytical consideration.
Trees. The organism in vegetation, as well as in animal life, being an element
of great variety, the influence of physical conditions becomes somewhat modified in
different countries by the species met with, therefore a few data shall be quoted
in reference to trees. The highest in the Himalaya are coniferous trees (not unlike
those in our Alps): we met with them at a mean temperature of 45° Fahr., up to
11,800 feet. In Tibet leaf-trees, and amongst them almost exclusively cultivated
trees, even fruit trees, are the highest. As the highest group of cultivated trees—
probably the highest leaf-trees of the globe—the poplar trees (populus euphratica) in
the garden of the Mangnang monastery, 13,460 feet, must take the first place; the
mean temperature of the year deduced from the isothermal profile is 37° Fahr. In
the Alps trees like the cembras near Eofen1 answer to an annual mean of 31° Fahr.
1 For details see above, p. 475, note 3.
GLACIERS.
Physical geography presents many phenomena which, though not exclusively
dependent upon temperature, show so decided a connection with it, that in order to
complete the researches concerning its distribution in different provinces and at various
heights, a comparison with at least some of the principal features has to be taken into
analytical consideration.
Trees. The organism in vegetation, as well as in animal life, being an element
of great variety, the influence of physical conditions becomes somewhat modified in
different countries by the species met with, therefore a few data shall be quoted
in reference to trees. The highest in the Himalaya are coniferous trees (not unlike
those in our Alps): we met with them at a mean temperature of 45° Fahr., up to
11,800 feet. In Tibet leaf-trees, and amongst them almost exclusively cultivated
trees, even fruit trees, are the highest. As the highest group of cultivated trees—
probably the highest leaf-trees of the globe—the poplar trees (populus euphratica) in
the garden of the Mangnang monastery, 13,460 feet, must take the first place; the
mean temperature of the year deduced from the isothermal profile is 37° Fahr. In
the Alps trees like the cembras near Eofen1 answer to an annual mean of 31° Fahr.
1 For details see above, p. 475, note 3.