他们注意到那时只有两个沼泽有泥炭丘，而1957年空中拍摄的该地区照片显示所有沼泽都有泥炭丘。
They noted at that timethat only two of the bogs contained palsas, whereas aerial photos takenin 1957 showed palsas present in all of the bogs.
因为马丘·比丘遗址的容量有限，所以争取更多商机仍需仰赖马丘·比丘本身的魅力。
Since capacity at the ruins is limited, so is the scope for more services to Machu Picchu itself.
研究人员通过观测被称为泥炭丘的小丘来测量永冻带边界北退的程度，泥炭丘是在北部泥炭沼泽含冰的土壤上自然形成的。
The researchers measured the retreat of the permafrost border byobserving hummocks known as "palsas, " which form naturally over icecontained in the soil of northern peat bogs.
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