听力原文

来到了落基山国家公园 ，看到了最高峰是久久峰(Longs Peak)，它高达14255尺。这里大多数是陡峭的悬崖和锯齿状的峭壁，究竟是什么原因呢？值得探索！

Back on the ground, Anderson is looking for evidence that will reveal the processes that shaped the jagged peaks. On a hillside, he finds mysterious large boulders scattered across the valley floor. A closer look uncovers some secrets about their origin.

"I'm standing in front of a rounded boulder that itself is sitting on a smooth, bedrock （基岩）outcrop（露出地面的岩层）. Both the boulder and the outcrop are covered in lichen （地衣，苔藓）here of green to black to grey colours. And therefore I had to whack up a piece of the rock in order to see inside the rock. And indeed it is different. The mineral(s) that I see in the texture of the rock is different from the underlying rock. And therefore the rock is (a) foreign to this particular site."

Anderson searches the ground for more clues as to how this massive boulder got here. Nearby he finds a smooth surface with very fine scratch marks.

"I'm sitting on a polished surface. This little piece right here is smooth to the touch. And if I look at it in a certain way the light glints （闪闪发光）off, but just right I can see that there are scratches running in this direction across the surface."

The only force that could have produced this fine parallel scratches on the rock is ice, and lots of it. It's a clue that a massive glacier once filled this valley.

"And that tells me that the glacier came down the valley, came across this surface and eroded it. Each one of these scratches corresponds to a sand grain embedded in the sole of the ice, that just like sandpaper smoothes off the surface. So zillions of sand grains over thousands of years will have eroded this surface smooth."

As glaciers flowed down the valley, they picked up rocks and grit. The ice pushed down on these cutting tools with the weight of over a thousand fully loaded garbage trucks. It left scratch marks all over the Rockies up to a thousand feet high. This is evidence that a massive wall of ice covered this part of the Rockies and shaped the Mountains. The ice ripped out the rock from the valley walls and left behind the jagged cliffs and rugged edges.

小编有约：注意细节的人很容易成功，在这里作者就偶然发现圆滑的石头上面有小小的划痕，进而通过划痕发现冰川，通过冰川发现冰里面的沙子，通过沙子发现类似砂纸的功效。从而推断出为什么这里是陡峭的悬崖和锯齿状的峭壁。本文为小编自己翻译以及讲解的文章，如有改进的地方请大家留言！如有转载请注明来源！

课后题目：Daisy很想建议大家爬爬山，感受大自然的魅力，想一想自己家乡的山中会发生怎样的故事让人难忘呢？参考译文

返回地面，安德森寻找形成锯齿状山峰的证据。在一个山坡上，他发现了神秘的大石头散落了整个谷底。再仔细一看发现有关其起源的一些秘密。

我正站在一个圆形的巨石前面。这块巨石坐落在一块平稳、露出地面的基岩上，同时绿绿的苔藓点缀在这些黑灰色的岩石上面。因此，我不得不捶了一块岩石拿来研究，看看岩石里面有什么样的成分。而事实上，表层的岩石和底层的岩石是不同的。因此，这种岩石在这里是一个外来者。

安德森为了找出这庞大的巨石究竟是如何来到这里，他开始搜集更多的线索。在附近，他发现一个表面光滑并且细细的划痕。

我坐在圆滑的岩石表面，这小片地摸起来手感细腻，如果我在某个角度看它，可以看到闪闪的亮光，但是，我忽然发现，在它的表面上有一道划痕。

唯一能够产生这种精细的平行的划痕，就只能是冰，而且是大量的冰。所以巨大的冰川曾经填补了这个山谷。

这就等于说，冰川往下，流到了山谷，来到岩石的表面，不断地侵蚀着岩石。每一道划痕对应冰中一颗沙子的痕迹，像用砂纸打磨后的平滑光亮。因此，想想几千年来，不计其数的沙子将这里的表面打磨的光滑明亮。

随着冰川向下流到山谷，它们抬高了岩石和砂砾。 冰用着极大的力量向下推这些切削工具，差不多是一千辆满载垃圾的卡车重量。这样留下的划痕遍布整个落基山脉，直到一千英尺高。这可以向我们证明，曾经有大规模的冰墙覆盖了这部分的落基山脉然后雕琢了这里。冰从峡谷的墙壁渗透进岩石，并把这里变成了陡峭的悬崖和锯齿状的峭壁。重点讲解
注释：① reveal vt. 显示；透露；揭露；泄露
n. 揭露；暴露；门侧，窗侧
词组：
reveal itself v. 呈现，出现；被认知
reveal all 显示全部（计算机操作命令）
例句：
1. Your list will reveal your true feelings.
你的列表将要揭露你真实的感受。
2. These plans reveal a complete failure of imagination.
这些计划显得毫无想象力。

② scratch n. 擦伤；抓痕；刮擦声；乱写
adj. 打草稿用的；凑合的；碰巧的
vt. 抓；刮；挖出；乱涂
vi. 抓；搔；发刮擦声；勉强糊口；退出比赛
例句：
1. I had to scratch my head to remember his name.
我只想苦苦地回忆他的名字。
2. He began to scratch along for himself at an early age.
他从很小的时候起就开始自己挣饭吃。

③ come across v. 偶遇；无意中发现；讲得清楚明白；给人……印象
例句：
1. I have come across a curious plant.
我发现一种珍奇植物。
2. He come across this in a curio shop.
他在一个古玩店里偶尔发现了这个。

句子讲解：

1.The only force that could have produced this fine parallel scratches on the rock is ice, and lots of it.

　　【结构简析】这里的"that"是定语从句，修饰前面的"force"。

　　【参考译文】唯一能够产生这种精细的平行的划痕，就只能是冰，而且是大量的冰。

　　2. This is evidence that a massive wall of ice covered this part of the Rockies and shaped the Mountains.

　　【结构简析】 这里的"that"引导的是名词性从句，真正的主语是后面的 "a massive wall of ice"。

　　【参考译文】这可以向我们证明，曾经有大规模的冰墙覆盖了这部分的落基山脉然后雕琢了这里。