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Narrator:Listen to a part of lecturer in a geology class.
獨白:聽下面一段關于地質學的講座
Professor:Now there are some pretty interesting caves in parts of the western United States, especially in national parks.
教授:現在在美國西部某些地方發現了一些有趣的洞穴，尤其是在國家公園一帶。
There is one part that has over a hundred caves, including some of the largest ones in the world.
有一個地方發現了超過 100 個洞穴，其中一個的規模為世界最大。
One of the more interesting ones is called Lechuguilla Cave.
這些洞穴中，比較有趣的一個名叫拉曲吉亞洞穴。
Lechuguilla has been explored a lot in recent decades.
拉曲吉亞在近幾十年被發掘過幾次。
It's a pretty exciting place I think.
我覺得它是一處讓人激動的遺址。
It was mentioned only briefly in your books.
你們的書中只是大概提了一下。
So can anyone remember what it said? Ellen?
有人記得書里是怎么描述它的嗎？艾倫？
Student:It's the deepest limestone cave in the U.S.?
學生:書里說它是美國最深的石灰巖洞穴。
Professor:That's right. It's one of the longest and deepest limestone caves not just in the country but in the world. Now, what else?
教授:正確。不過它的深度、長度不僅是我國第一，而且更是世界第一。還有別的補充嗎？
Student:Well, it was formed because of sulfuric acid, ght?
學生:嗯，它是由于硫酸的腐蝕而形成的，對嗎？
Professor:That's it. Yeah, what happens is you have deep underground oil deposits and there are bacteria.
教授:是那樣的。對，事情是，當地下深處有油類囤積和細菌微生物時，就會有腐蝕。
Here let me draw a diagram.
我來畫張圖吧！
Part of the limestone rock layer is permeated by water from below.
地下石灰巖的一部分被地下水淹沒。
Those curly lines are supposed to be cracks in the rock.
我們假設這些波浪線代表了巖石的裂縫。
Below the water table and rock is oil.
石油出現的位置，在地下水位線和巖石之下。
Bacteria feed on this oil and release hydrogen sulfide gas.
細菌靠分解石油維持生命，在這個過程中，就會有硫化氫釋放出來。
This gas is hydrogen sulfide, rises up and mixes with oxygen in the underground water that sits in the cracks and fissures in the limestone.
硫化氫上升，與地下水中溶解的氧氣混合，滲入石灰巖的縫隙中。
And when hydrogen sulfide reacts with the oxygen in the water, the result of that is sulfuric acid, Ok?
并且當硫化氫與水中的氧氣反應時，會產生硫酸，對吧？
Sulfuric acid eats away at limestone very aggressively.
硫酸對石灰巖的腐蝕性是極強的。
So you get bigger cracks and then passageway is being formed along the openings in the rock and it's all underground. Ah yes, Paul?
所以這個裂縫就會越來越大，逐漸地就會有一條通道沿著巖石的斷裂層形成。這個過程全部是發生在地下，保羅有什么問題嗎？
Student:So that water... It's not flowing, right? It's still?
學生:這樣的話，地下水…難道它是不流動的，對嗎？它是靜止的？
Professor:Yes, so there are two kinds of limestone caves.
教授:是的，所以世界上有兩種類型的石灰巖洞穴。
In about 90 percent of them, you have water from the surface, streams, waterfall or whatever-moving water that flows through cracks found in limestone.
百分之九十的洞穴的表面都有水，比如小溪，瀑布等各種沿著巖石縫隙流動的水流。
It's the moving water itself that wears away at the rock and makes passageways.
腐蝕巖石，形成通道的因素就在于這些水流自身。
Also, in surface water, there is a weak acid, carbonic acid, not sulfuric acid but carbonic acid that helps dissolve the rock.
而且，這些地表水流中，存在弱酸，比如碳酸，而不是硫酸。
With a little help from this carbonic acid, moving water forms most of the world's limestone caves.
這種酸也能腐蝕巖層。依靠這種弱酸的幫助和水流的沖擊力，大部分石灰巖洞穴形成了。
When I was researching this for a study a few years ago, I visited a couple of these typical limestone caves, and they were all very wet, you know, from streams and rivers.
幾年前我做這項研究時，我探訪了其中幾個比較典型的洞穴；它們都很潮濕，你們也知道這是因為水流的緣故。
This flowing water carved out the caves and the structures inside them.
總之，這些水流鑿穿了巖石，造成了這些洞穴及其內部結構。
Student:But not Lechuguilla?
學生:不過這些洞穴中不包括拉曲吉亞？
Professor:Dry as a bone.
教授:拉曲吉亞干燥得像塊硬骨頭。
Well, that might be a bit of an exaggeration.
嗯，這個比喻有些夸張了。
But it's safe to say that it's sulfuric acid and not moving water that formed Lechuguilla cave and those few other ones like it.
不過，我們可以很穩妥地說，是硫酸而非水流使得拉曲吉亞等洞穴成形。
In fact, there is no evidence that flowing water has even gone in or out of the cave.
實際上，沒有證據表明水流曾在拉曲吉亞附近進出過。
So, it's like a maze.
所以，拉曲吉亞洞穴就像一座迷宮，
You have passageways all around.
里面到處都是通道，
There are wide passages, narrow ones at all different depths, like underground tunnels in the limestone.
寬的，窄的，各種深度都有。并且，由于它是在地下形成的，某些通道完全沒有與地面接通。
And, since they were created underground and not from flowing surface water, not all these passageways have an opening to the outside world.
并且…嗯，有證據表明水流與拉曲吉亞沒有絲毫關系。
And.. .and there is other evidence that flowing water wasn't involved in Lechuguilla. We've said that sulfuric acid dissolves limestone, right, and forms the passageways?
我們講過，硫酸可以溶解石灰巖，是吧？并且這種腐蝕形成了通道。
What else does sulfuric acid do? Paul?
硫酸還有什么別的功能呢？保羅？
Student:Ah, leaves a chemical residue and...
學生:嗯，它會遺留下一些殘渣，并且…
Student:Gypsum, right?
學生:這些殘渣就是石膏，對嗎？
Professor:Yep, you'll find lots of gypsum deposited at Lechuguilla.
教授:正確，你們會在拉曲吉亞洞穴中發現許多沉積下來的石膏。
And, as we know, gypsum is soluble in water.
同時，我們知道，石膏是可以溶解在水中的。
So if there were flowing water in the cave, it would dissolve the gypsum.
所以如果拉曲吉亞附近有水流存在的話，它就會使石膏溶解。
This is part of what led us to the realization that Lechuguilla is in that small group of waterless caves.
這就是為什么我們會得出拉曲吉亞是為數不多的、并非因水流形成的洞穴之一。
And Lechuguilla is pretty much dormant now.
現在拉曲吉亞洞穴的形成已經停滯了。
It's not really forming any more.
它現在已經不再有進一步變化了。
But, there is other ones like it, for example, in Mexico, that are forming.
不過，也有其他與之相似的洞穴依舊進行著這個過程，比如，在墨西哥就有一個。
And when cave researchers go to explore them, they see and smell, the sulfuric acid and gases of...er...phew...now, something else, think of rotten eggs.
當研究人員探索這些洞穴時，他們看到、聞到硫酸，和像…的氣體，嗯…，想想臭雞蛋的味道吧！
And, it's not just the smell.
而且，不僅是只有這種味道，
Explorers even need to wear special masks to protect themselves from the gases in these caves. OK? Paul.
研究員還得帶上專門的面具，使自己和這種氣體隔絕開。保羅，你有問題嗎？
Student:Yeah, how about what these caves look like on the inside?
學生:嗯，這些洞穴里面是什么樣子的？
Professor:Well, the formations.. .there is really something.
教授:嗯，里面形成的物質…里面的確有些東西。
There's such variety there like nothing anywhere else in the world, some of them are elaborate looking, like decorations.
不過這些物質各式各樣，有些看上去很像精心設計的裝飾物。
And a lot of them are made of gypsum and could be up to 20 feet long.
其中相當一部分都是由石膏構成的，高度達到了 20 英尺，
It's pretty impressive.
非常壯觀。
