The American side of the falls were shut off in 1969 to study the buildup of rock at the base of the falls.

美国部分的大瀑布曾经1969年关闭过，当是为了研究瀑布下的岩基。

A batholith is a geological formation created when a vast quantity of molten rock rises through a planet's crust, spreading out sideways as it does so.

岩基是一种地质，大量熔融岩石穿过行星地壳扩散形成。

From here, we worked our way carefully across the rock base.

【work】我们从这里小心翼翼地穿过岩基。

The rocks of Yosemite, for example, are parts of the Sierra Nevada batholith, uncovered and spectacularly sculpted by subsequent erosion.

例如， 优胜美地的岩石是内华达山脉岩基的一部分，后来被侵蚀作用揭露并壮观地雕琢而成。

The Compton-Belkovich batholith is also made of granite, which is what gave it away.

康普顿-贝尔科维奇岩基也是花岗岩成的，这暴露了它的身份。

On Earth, these batholiths are composed mostly of granite.

地球上，这些岩基主要花岗岩成。