alluvial fan

基本解釋

At first light, I started my trek up an alluvial fan into an unnamed canyon in the Cottonwood Mountains.
天剛亮，我就從一片沖積扇區(qū)（峽穀山口的扇形沉積物）処開始了旅程，進入了卡頓伍德山脈中的一個無名峽穀。
The portion of the crater where Curiosity will land has an alluvial fan likely formed by water-carried sediments.
好奇號所要降落的隕坑処有一塊很可能是由水流沉積物所形成的沖積扇。
Lake Morari on the Tibetan Plateau is fed by a glacial river that has formed a dramatic apron of sediment, known as an alluvial fan, over the years.
西藏高原（TibetanPlateau）上的莫拉裡湖（LakeMorari）是由一條冰川河流沖積形成的，長年以來，這條冰川河流在入口処戯劇性地形成了一個圍裙形狀的沉積泥沙區(qū)，被稱爲沖積扇形地。
uusapp.blog.163.com

There was an alluvial fan at the base of the mountain, for instance, that had some of the same sediments as Eberswalde.
NEWYORKER: The Martian Chroniclers

a fan-shaped accumulation of silt, sand, gravel, and boulders deposited by fast-flowing mountain rivers when they reach flatter land