安裝中文字典英文字典辭典工具!
安裝中文字典英文字典辭典工具!
|
- Tropical Fossils in Alaska | Geophysical Institute
Paleobotanist Jack A Wolfe of the United States Geological Survey at Menlo Park, California, has found a number of tropical rain forest fossils along the eastern Gulf of Alaska These include several kinds of palms, Burmese lacquer trees, mangroves and trees of the type that now produce nutmeg and Macassar oil
- Cottonwood and Balsam Poplar | Geophysical Institute
The Klukwan giant belies the belief that trees tend to get smaller the farther north one goes Both balsam poplar and cottonwood have value for fuel wood, pulp and lumber
- Northern Tree Habitats | Geophysical Institute
Why take a chance with exotics, when native trees have proven their ability to survive? Several reasons prompt testing of foreign tree species Human activities often create and maintain new, sometimes artificial habitats that native trees are not adapted to Exotics may have strong wood, large fruits or straight boles that are lacking in the
- Pollen season arrives, blame the trees | Geophysical Institute
The air is rich with pollen because spring is the mating season for trees The first step in a tree's reproductive dance is to release sperm, safely held in the center of a pollen grain Trees release an incredible amount of pollen to improve the odds of finding a female flower
- More on Why Tree Trunks Spiral | Geophysical Institute
Granted, not all trees exhibit the same twist, but the majority of them do The phenomenon can be likened to the claim that water will always spiral out of a drain in a counter-clockwise direction in the northern hemisphere
- Trees as Earthquake Fault Indicators | Geophysical Institute
A swath of dead, tilted and broken trees now makes obvious the trace of the Fairweather fault that broke in July 1958 to devastate Lituya Bay and nearby parts of southeastern Alaska Sagging or tilting of the ground along a fault trace causes trees there to tilt or even fall
- Hoarfrost Formation | Geophysical Institute
By late winter, intricate buildups of hoarfrost crystals have formed on wooden poles and other objects Warming rays of the sun cause evaporation of whatever frost may have formed on the south side of vertical poles and trees Conduction within metal poles causes enough heat transfer to entirely remove the hoarfrost crystals from the pole surface
- Trees for a Cold Climate - Geophysical Institute
The hardiest trees rely on physics more than on chemistry to make it through the winter When the seasonal chill begins to reach black or white spruce, for example, the sap leaves their living cells and flows into intercellular spaces There, ice crystals can form without damaging anything vital for the tree's survival
|
|
|