評(píng)論
打印
字號(hào):
Moving glaciers can cause erosion on mountains, but the coldest glaciers, frozen in place, protect mountains and allow them to grow taller. Cynthia Graber reports
冰川移動(dòng)會(huì)侵蝕山地（冰川移動(dòng)通常會(huì)導(dǎo)致出現(xiàn)角峰和冰斗谷），但是最冷的冰川被凍得固定在某個(gè)地方，就會(huì)保護(hù)山脈并且還會(huì)讓它們“長(zhǎng)高”。Cynthia Graber 報(bào)道
Glaciers slowly grind their way over mountains and plains, moving immense boulders and carving out fjords. That’s true in temperate regions, where glaciers—glacially—flow downhill. Over thousands of years, the frozen masses can scrape miles off of mountains. Researchers call it the glacial buzz-saw.
But for the very coldest climes, researchers now offer a counter-intuitive view of glaciers – they actually help mountains grow. The finding was published in the journal Nature. [Stuart Thomson et al., http://bit.ly/aIAKcW]
A team led by scientists from the University of Arizona studied mountains in remote areas of Patagonia in South America.The Andes are actively growing. Hot rocks are shoved to the top, and erosion brings them back down the sides.The team collected 146 samples of rocks from mountainsides and then dated the rocks’ so-called cooling age, which reveals when the rock was exposed by erosion.
They found that erosion happened faster in the warmer mountains to the north, and more slowly in the colder mountains in the south.
Turns out that when glaciers are cold enough they don’t move much. Instead, they seal the mountains, protecting them from erosion. The scientists call the effect "glacial-armoring": an invaluable assist for peak performance.
—Cynthia Graber
收藏
