THE ANTIQUITY OF MOUNT RUSHMORE By the late JOSEPH P. CONNOLLY

 President, South Dakota School of Mines

 

At the Battle of the Pyramids, Napoleon is reported to have exhorted¹ his men by saying, “Soldiers, from these pyramids forty centuries look down upon you.” From the standpoint of human history four thousand years represent great antiquity² indeed. But as one gazes upon the rugged³ slopes of Mount Rushmore, he is face to face with antiquity beside which the age of the Egyptian pyramids seems but a moment.

 

How old is the granite⁴ of Rushmore? We have a yardstick⁵ by which we can measure that quite accurately⁶. Not far from the mountain, in a subsidiary mass of granite, there was found a few years ago a small piece of coal-black, lustrous⁷ mineral known as pitchblende or uraninite, of which the chief constituent⁸ is the heaviest known element, uranium. We know that uranium continually undergoes atomic disintegration⁹, changing at a slow, but uniform and measurable rate into lighter¹⁰ elements. The end product of this change is the metal lead. If we submit the specimen¹¹ of pitchblende to chemical analysis, determine how much lead it contains, how much uranium is still left, it is a comparatively simple calculation to determine from the known rate of change, the number of years that have elapsed since the pitchblende came into existence. That experiment has been performed and the result is one billion four hundred and sixty-five million (1,465,000,000) years. Bear in mind that this enormous figure represents the time that has elapsed since the molten rock came to rest at some depth under the surface of the earth, and cooled sufficiently¹² to crystallize into granite. It represents the age of the solid granite.

 

But, although the granite of which the mountain is composed dates back to a period almost inconceivably remote, Mount Rushmore itself is much younger. We know that all of the granite mountains of the southern Black Hills were carved out of the rocks by the process of erosion. Field evidence indicates that fairly early in the Tertiary period, approximately thirty million years ago, erosion had carved out the topography of the Black Hills into much the same stage as we see it today. Perhaps Mount Rushmore was not fully¹³ born in that period; its form may not yet have been completely sculptured under the chisel¹⁴ of time, but we know that its age must be measured in millions of years and not in centuries.

 

Mount Rushmore is a child of weathering and erosion. They brought the mountain into being and gave it form. But those relentless¹⁵ parents will not be content to leave their child as they fashioned it. They will continue their work of disintegration on the surface of the rock and along the cracks, until eventually they will completely destroy the mountain they formed, and long before the mountain will have been destroyed, the magnificent carvings¹⁶ of man will disappear. “How long,” we anxiously ask, “will the carvings endure?” Two processes will tend eventually to destroy the memorial, chemical weathering and physical disintegration.

 

 

A typical view from the Needles highway with the Cathedral Spires¹⁷ in the background.

 

19

 

Fantastic formations in the Badlands. The variegated¹⁸ coloring is at its best in the early morning or the late evening.

 

Chemical weathering will take place very slowly, so slowly that if it were the only destructive process we had to consider, we could with some confidence say that the memorial would endure for hundreds of thousands of years. And the progress of chemical weathering will probably be impeded¹⁹ by the sculpturing of the memorial, for on the figures the rock will be smoother, water will drain off more rapidly instead of penetrating²⁰, lichens²¹ and other vegetation will not have as secure a foothold as on the natural face of the rock, and thus will not contribute to so great an extent their destructive acids to such waters as do penetrate²².

 

Physical disintegration is somewhat more to be feared. This operates in two ways, by exfoliation due to changes in temperature, and by frost action. Differential stresses set up by unequal expansion and contraction²³, owing to the poor heat conductivity of granite, tend to spall off or exfoliate the surface layers of rock.

 

When water gets into the cracks and pores of the rocks and freezes, it exerts an enormous pressure, a pressure that will spall off flakes²⁴ and blocks of rock. The artist and his associates, fully aware of this hazard, have guarded against it. All cracks and fissures²⁵ have been carefully avoided in the sculpturing so far as is possible. Such as have been impossible to avoid are being sealed to prevent the ingress of water, thus inhibiting²⁶ to a very large extent both frost action and chemical weathering.

 

We have traced in part the geological history of the Mount Rushmore region, hoping that by learning something of its past we may predict something of its future. We see the hazards to which the memorial is exposed. We must frankly²⁷ recognize them and guard against them so far as possible, as it would be folly²⁸ to ignore them. If the science of geology can do no more in a practical way for mankind than to point out dangers and sound warnings, it does a worth while service. “How long will the memorial last?” Geology cannot answer specifically. An eminent²⁹ geologist³⁰ has already given as definite an answer as it is possible to give, and I can do no better than to close by quoting from the address given by the late Dr. C. C. O’Harra at the unveiling of the head of Washington.

 

“How long will Mount Rushmore last? Many millions of years. The number nobody knows. How long will endure this monumental, sculptured figure of the Father of our Country which today we unveil? One hundred years? Yes. One thousand years? Yes. A hundred thousand years? In all likelihood, yes. A half million years? Possibly so, nobody knows. The time at any rate will be long, far longer than we can readily comprehend. And this doubtless will abundantly suffice.”

 

1 exhorted   

v.劝告，劝说( exhort的过去式和过去分词 )

参考例句：

• The party leader exhorted his members to start preparing for government. 该党领袖敦促党员着手准备筹建政府。
• He exhorted his elder. 他规劝长辈。 来自《简明英汉词典》

2 antiquity   

n.古老；高龄；古物，古迹

参考例句：

• The museum contains the remains of Chinese antiquity.博物馆藏有中国古代的遗物。
• There are many legends about the heroes of antiquity.有许多关于古代英雄的传说。

3 rugged   

adj.高低不平的，粗糙的，粗壮的，强健的

参考例句：

• Football players must be rugged.足球运动员必须健壮。
• The Rocky Mountains have rugged mountains and roads.落基山脉有崇山峻岭和崎岖不平的道路。

4 granite   

adj.花岗岩，花岗石

参考例句：

• They squared a block of granite.他们把一块花岗岩加工成四方形。
• The granite overlies the older rocks.花岗岩躺在磨损的岩石上面。

5 yardstick   

n.计算标准，尺度；评价标准

参考例句：

• This is a yardstick for measuring whether a person is really progressive.这是衡量一个人是否真正进步的标准。
• She was a yardstick against which I could measure my achievements.她是一个我可以用来衡量我的成就的准绳。

6 accurately   

adv.准确地，精确地

参考例句：

• It is hard to hit the ball accurately.准确地击中球很难。
• Now scientists can forecast the weather accurately.现在科学家们能准确地预报天气。

7 lustrous   

adj.有光泽的；光辉的

参考例句：

• Mary has a head of thick,lustrous,wavy brown hair.玛丽有一头浓密、富有光泽的褐色鬈发。
• This mask definitely makes the skin fair and lustrous.这款面膜可以异常有用的使肌肤变亮和有光泽。

8 constituent   

n.选民；成分，组分；adj.组成的，构成的

参考例句：

• Sugar is the main constituent of candy.食糖是糖果的主要成分。
• Fibre is a natural constituent of a healthy diet.纤维是健康饮食的天然组成部分。

9 disintegration   

n.分散，解体

参考例句：

• This defeat led to the disintegration of the empire.这次战败道致了帝国的瓦解。
• The incident has hastened the disintegration of the club.这一事件加速了该俱乐部的解体。

10 lighter   

n.打火机，点火器；驳船；v.用驳船运送；light的比较级

参考例句：

• The portrait was touched up so as to make it lighter.这张画经过润色，色调明朗了一些。
• The lighter works off the car battery.引燃器利用汽车蓄电池打火。

11 specimen   

n.样本，标本

参考例句：

• You'll need tweezers to hold up the specimen.你要用镊子来夹这标本。
• This specimen is richly variegated in colour.这件标本上有很多颜色。

12 sufficiently   

adv.足够地，充分地

参考例句：

• It turned out he had not insured the house sufficiently.原来他没有给房屋投足保险。
• The new policy was sufficiently elastic to accommodate both views.新政策充分灵活地适用两种观点。

13 fully   

adv.完全地，全部地，彻底地；充分地

参考例句：

• The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气，然后全部呼出。
• They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。

14 chisel   

n.凿子；v.用凿子刻，雕，凿

参考例句：

• This chisel is useful for getting into awkward spaces.这凿子在要伸入到犄角儿里时十分有用。
• Camille used a hammer and chisel to carve out a figure from the marble.卡米尔用锤子和凿子将大理石雕刻出一个人像。

15 relentless   

adj.残酷的，不留情的，无怜悯心的

参考例句：

• The traffic noise is relentless.交通车辆的噪音一刻也不停止。
• Their training has to be relentless.他们的训练必须是无情的。

16 carvings   

n.雕刻( carving的名词复数 )；雕刻术；雕刻品；雕刻物

参考例句：

• The desk was ornamented with many carvings. 这桌子装饰有很多雕刻物。 来自《简明英汉词典》
• Shell carvings are a specialty of the town. 贝雕是该城的特产。 来自《简明英汉词典》

17 spires   

n.（教堂的） 塔尖，尖顶( spire的名词复数 )

参考例句：

• Her masts leveled with the spires of churches. 船的桅杆和教堂的塔尖一样高。 来自《简明英汉词典》
• White church spires lift above green valleys. 教堂的白色尖顶耸立在绿色山谷中。 来自《简明英汉词典》

18 variegated   

adj.斑驳的，杂色的

参考例句：

• This plant has beautifully variegated leaves.这种植物的叶子色彩斑驳，非常美丽。
• We're going to grow a variegated ivy up the back of the house.我们打算在房子后面种一棵杂色常春藤。

19 impeded   

阻碍，妨碍，阻止( impede的过去式和过去分词 )

参考例句：

• Work on the building was impeded by severe weather. 楼房的施工因天气恶劣而停了下来。
• He was impeded in his work. 他的工作受阻。

20 penetrating   

adj.（声音）响亮的，尖锐的adj.（气味）刺激的adj.（思想）敏锐的，有洞察力的

参考例句：

• He had an extraordinarily penetrating gaze. 他的目光有股异乎寻常的洞察力。
• He examined the man with a penetrating gaze. 他以锐利的目光仔细观察了那个人。

21 lichens   

n.地衣( lichen的名词复数 )

参考例句：

• The only plants to be found in Antarctica are algae, mosses, and lichens. 在南极洲所发现的植物只有藻类、苔藓和地衣。 来自辞典例句
• Litmus: Mixture of coloured organic compounds obtained from several species of lichens. 石蕊：从几种地衣类植物中获取的带色有机化合物的混合物。 来自互联网

22 penetrate   

v.透(渗)入；刺入，刺穿；洞察，了解

参考例句：

• Western ideas penetrate slowly through the East.西方观念逐渐传入东方。
• The sunshine could not penetrate where the trees were thickest.阳光不能透入树木最浓密的地方。

23 contraction   

n.缩略词，缩写式，害病

参考例句：

• The contraction of this muscle raises the lower arm.肌肉的收缩使前臂抬起。
• The forces of expansion are balanced by forces of contraction.扩张力和收缩力相互平衡。

24 flakes   

小薄片( flake的名词复数 )； （尤指）碎片； 雪花； 古怪的人

参考例句：

• It's snowing in great flakes. 天下着鹅毛大雪。
• It is snowing in great flakes. 正值大雪纷飞。

25 fissures   

n.狭长裂缝或裂隙( fissure的名词复数 )；裂伤；分歧；分裂v.裂开( fissure的第三人称单数 )

参考例句：

• Rising molten rock flows out on the ocean floor and caps the fissures, trapping the water. 上升熔岩流到海底并堵住了裂隙，结果把海水封在里面。 来自辞典例句
• The French have held two colloquia and an international symposium on rock fissures. 法国已经开了两次岩石裂缝方面的报告会和一个国际会议。 来自辞典例句

26 inhibiting   

抑制作用的，约束的

参考例句：

• The high cost of borrowing is inhibiting investment by industry in new equipment. 借款的高成本抑制了企业对新设备的投资。
• The pesticides affect the nervous system by inhibiting the enzyme cholinesterase. 这类农药抑制胆碱酯酶而影响神经系统。

27 frankly   

adv.坦白地，直率地；坦率地说

参考例句：

• To speak frankly, I don't like the idea at all.老实说，我一点也不赞成这个主意。
• Frankly speaking, I'm not opposed to reform.坦率地说，我不反对改革。

28 folly   

n.愚笨，愚蠢，蠢事，蠢行，傻话

参考例句：

• Learn wisdom by the folly of others.从别人的愚蠢行动中学到智慧。
• Events proved the folly of such calculations.事情的进展证明了这种估计是愚蠢的。

29 eminent   

adj.显赫的，杰出的，有名的，优良的

参考例句：

• We are expecting the arrival of an eminent scientist.我们正期待一位著名科学家的来访。
• He is an eminent citizen of China.他是一个杰出的中国公民。

30 geologist   

n.地质学家

参考例句：

• The geologist found many uncovered fossils in the valley.在那山谷里，地质学家发现了许多裸露的化石。
• He was a geologist,rated by his cronies as the best in the business.他是一位地质学家，被他的老朋友们看做是这门行当中最好的一位。