Choose the right word for each gap.

Located on the Kamchatka peninsula in Eastern Siberia, Russia’s world famous Valley of the Geysers is one of 1) ... five places on Earth where hot springs punch holes through the Earth’s crust to eject boiling water and steam skywards.
Until recently, the area 2) ... of some ninety geysers and hundreds of thermal pools, steam jets and mud pots. Sadly, this natural 3) ... was all but obliterated by a massive landslide in 2007. An entire mountainside collapsed in a nearby valley, hurling mud, stones, gravel, snow and ice into the geyser valley and covering two-thirds of it in the 4) ... of an eye.
Following the natural disaster, officials met to consider removing the landslide 5) ... in order to return the valley to its former glory. But it was agreed by all that it would be inherently wrong not to allow nature to take its course. The Kamchatka area is a strictly controlled nature reserve 6) ... to observe natural processes, and the landslide was a natural process. The opportunity to 7) ... the amazing natural transformation of a landscape and the birth of a completely new valley is, officials concluded, a unique opportunity that should be embraced.