I will write an article summary in English,
but I'm sorry that I did not get Japan Times Weekly yet..
So I found the article on the online.

The title of the article is Mammoth Cave in Kentucky.

It is begin the sentence, At more than 350 miles (563 km) long, the Mammoth–Flint Ridge cave system in central Kentucky is the longest cave system in the world.

The article said that,  the cave was formed over the past 10 million years by slightly acidic rainwater filtering through the cracks of a limestone ridge and the river was created in underground. But though this cave was very old and found long years ago, explores still discover new passages.The cave's rokcs have very interesting form, and it also has several rakes, rivers, and waterfalls and so on. And there are animals such as fish, beetles and so on. You can see this cave in Mammoth Cave in national park.

I think this cave has many story, because it was created for 10 millioms years ago. This cave has history, and it has seen many thing...that's interesting. And I also interested in the form of rocks of the cave. It was formed by reinfall, and cracks,  and maybe it will be change forever. I want to see it someday!!

english articles,
http://www.englisharticles.info/2012/02/26/mammoth-cave-in-kentucky/