Centennial
Page 7
Subsequent glaciers broadened the meadow and rearranged the rocks. Each mutilated the trees, but with that fine determination which marks so much of nature, they returned, and by the year 15,000 B.C. the valley had assumed its present form and was a place of enhanced beauty.
The second event happened long before the aspen and blue spruce had given the place its character, and we must go well back in time to understand it. About thirty-five million years ago, a pressure very deep within the mantle sent relatively small amounts of highly liquid magma probing upward at very high temperatures.
It sought out any weakness in the structure of the rock, and was especially inclined to surge into cracks where faces met, expanding them and filling them to the remotest cranny. This had happened often before, as can be seen in any large accumulation of mountain rock: invariably the rock will show where a hot igneous material had intruded itself into interstices, and this has occurred all over the world.
What made this incursion exceptional was that this particular flow of magma contained a high percentage of minerals, sometimes in pure state: galena, silver, copper filled the interstices. The liquid rock that crept into the long pipe underlying Blue Valley contained a large proportion of unalloyed gold.
The end of the pipe it filled lay only ninety feet below the surface of the valley, along the northern flank. It extended downward at an angle of forty degrees for nearly a quarter of a mile. It was not a large pipe, and therefore did not contain any fantastic amount of gold, but it was substantial, and it filled every crevice.
It lay undisturbed for more than thirty million years. When the area rose, it rose too. When minor faults appeared, it adjusted to them. And when the area subsided, the golden pipe fell with it, still ensconced under the north bank of the little stream. In time roots of the golden aspen formed a network above it.
When the first great glacier filled the valley it stripped away some fifty feet of cover protecting the near end of the pipe, but no other change occurred. Each succeeding glacier cut away a little more of the protection until the last one came. Sometime around the year 1,000 B.C. this glacier actually cut away six feet of the pipe and scattered the gold that it had contained along the bottom of the stream for a distance of some two hundred yards.
This same glacier, of course, deposited gravel over the exposed end of the pipe, so that it could not easily be detected, and hid the nuggets of gold that lay at the bottom of the stream. Then trees returned and the gold was buried again, but each autumn when leaves of the aspen turned, this was a valley that was doubly golden.
The third place was conspicuous from all directions, and spectacular, but what was significant about it was hidden, and we shall not know of it till later.
Some sixty-five million years ago—shortly after the emergence of the New Rockies—the river began hauling down an extraordinary amount of rock, gravel and sand, which it deposited in a thick overlay on the flat plains to the east. We have observed this phenomenon before, so there is no need to recapitulate, except to state that at the location we are talking about, a spot to the north of Centennial and slightly to the east, the deposit eventually, was more than two hundred feet thick.
When this process was completed, thirty-eight million years ago, the plains to the east were so built up that they blended harmoniously into the lower reaches of the New Rockies, creating a lovely sweep that extended in unbroken beauty several hundred miles into Nebraska and Kansas. This symmetry did not endure, for the New Rockies experienced a massive uplifting, which raised them above the gentle sweep. As a result, the river now dropped more steeply from the mountains, carrying with it many cutting rocks. It surged eastward and for twelve million years dominated the foothills, cutting them away, scraping down hillocks, and depositing on the plains new layers of soil characterized by a rocky, infertile content.
The great inland sea which had once dominated this area had long vanished, so that the building of this new rock had to be accomplished in open air. The river would bring down deposits, which would spread out in fans. Sun and wind would act upon them, and new deposits would form over them. Gradually, disparate components would begin to solidify, and as heavier forms accumulated on top, those on the bottom would coalesce to form conglomerates.
Each year the plains grew a little higher, a little more stable in their footing. Finishing touches were applied about eleven million years ago, when a sandstone rock was laid down, sealing the entire region. This final rock had a peculiar characteristic: at the spot we are talking about, north of Centennial, some variation occurred in the cement which bound the granular elements together. Different from the cement operating in nearby regions, it had been formed perhaps from volcanic ash which had drifted in; at any rate, it created an impermeable caprock which would protect the softer sandstone that rested beneath.
At last the vast job of building was ended. From the period when the New Rockies underwent their secondary uplift, some three hundred and twenty feet of solid rock and soil had been laid down, all protected by the caprock, and had there been an observer at the time, he could have been excused had he concluded that what he saw then, eight million years ago, would be the final structure of the plains.
But it was still the river which determined what the surface of the land would be, and starting eight million years ago, it once more began to tumble out of the mountains with greatly increased velocity, cutting and swirling and spreading far across the plains. It was engaged upon a gargantuan task, to scour away every vestige of the enormous quantity of land that had been contributed by the New Rockies. In some places it had to remove up to a thousand feet of burden; from extensive areas it had to cut away at least three hundred feet. But it succeeded ... except where that extra-hard caprock protected its monolith.
No matter how wild the torrents that raged down from the mountains, nor how compulsive the flash floods that cascaded across the plain after some torrential downpour, the monolith persisted. It covered an area no more than a quarter of a mile long, two hundred yards wide, but it resisted all assaults of the river. For millions of years this strange and solitary monolith maintained its integrity.
Neighboring sandstone covers were breached, and when they were gone, the softer areas they had protected were easily cut down by the river. Winds helped; meltwater from ice did its damage; and as the eons passed, the river completed its task: all remnants of land deposited by the New Rockies were swept away, except the solitary monolith.
And then, about two million years ago, the central portion of the caprock weakened, cracked during a heavy winter, and broke away. The softer rock which it had been protecting quickly deteriorated—say, over a period of two hundred thousand years—until it was gone.
Two pillars remained, about a quarter of a mile apart, each somewhat elongated in shape; the western was over five hundred feet long and two hundred feet wide, the eastern only three hundred and eighty feet long and a hundred and ninety wide. The western pillar was taller, too, standing three hundred and twenty feet above its pediment; the eastern, only two hundred and eighty.
They were extraordinary, these two sentinels of the plains. Visible for miles in each direction, they guarded a bleak and silent empire. They were the only remaining relics of that vast plain which the New Rockies had deposited; each bit of land the sentinels surveyed dated back to ancient times before the mountains were born.
The fourth special place is rather embarrassing to mention, after this parade of fractured cliffs, valleys packed with gold and high monuments of integrity; but eleven thousand years ago, when the main features of the New Rocky Mountain area had long been determined and the land looked pretty much as it looks today, a small, wandering muddy stream joined the river at the spot where Centennial was to be. It came in from the north and in its day must have been a helpful agent to the parent river in scouring off the debris sent down by the mountains. Now it was a miserable thing, carrying little water and serving more as a drainage ditch than a rivulet.
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sp; But along its western bank, not far from where it joined the river, its probing fingers had recently penetrated into a pocket of soluble stone lying some seven feet below the surface of the land. It formed a secret cave less than six feet long and only four feet wide. It would scarcely have been noticed except for a dramatic event which would occur in relation to it eleven thousand years after its creation by the meandering stream.
And so the stage is set. One billion, seven hundred million years of activity, including the building of at least two high mountain ranges and the calling into being of vast seas, have produced a land which is ready to receive living things.
It is not a hospitable land, like that farther east in Kansas or back near the Appalachians. It is mean and gravelly and hard to work. It lacks an adequate topsoil for plowing. It is devoid of trees or easy shelter. A family could wander this land for weeks and never find enough wood to build a house.
It lacks water—my God, how it lacks water. Rainfall at Centennial is only thirteen inches a year, when any farmer knows that to produce even miserly corn or wheat requires twenty-one. The extremes of temperature can be unbearable, from one hundred and nine in August to thirty-eight below in February.
It is a land subject to wild whims of nature. Sometimes a score of years will pass with almost no rain, so that crops perish and organized society stands in peril. At sixty- or seventy-year intervals unpredictable winds whip over the prairies, exhausting the land and everything that grows upon it. Duststorms greater than hurricanes and more persistent can sweep the region for months on end, filling all openings with grit. And as if this were not enough, at unexpected times and for unexplained reasons gigantic swarms of locusts can suddenly emerge from the west and darken the sky for three or four days running. They swarm in the air, more extensive than storm clouds, and capriciously they alight, eating every green thing that stands in their path. Then they rise and fly mysteriously on, landing and eating a few more times, then vanishing as inexplicably as they appeared.
But there is one thing about this land. Theoretically, it can be farmed. It is rich in minerals. It is the inheritor of two great mountain ranges; over several hundred million years it conserved deposits sent down by the mountains and is entitled to the richness it possesses. The growing season is adequate for most crops: late frost on May 10, first frost on September 27, with an average 139 frost-free days in between for the prudent farmer. The governing rule is simple.
“If you can lead water onto this land, you can grow anything.”
“Well, you wouldn’t try apples or oranges, would you?”
“No, but only because they can be grown better somewhere else.”
Corn and wheat? Magnificent. Sorghum? The best. Garden vegetables? None better.
“Like I said, you can grow anything. But two things grow better here than anywhere else on earth.”
“Such as?”
“Melons of any kind. You name it. And great big juicy sugar beets.”
The land cries for water. The bleakest desert, even the forbidding land about the two pillars, will flourish like a garden if only water can be got to it. Consequently, the crucial problem of this area will be the attempt of man to lead water onto his intractable land. If he can do that, if only he can do that, he will have at his disposal a paradise.
And finally there is the river, a sad, bewildered nothing of a river. It carries no great amount of water, and when it has some it is uncertain where it wants to take it. No ship can navigate it, nor even a canoe, with reasonable assurance. It is the butt of more jokes than any other river on earth, and the greatest joke is to call it a river at all. It’s a sand bottom, a wandering afterthought, a useless irritation, a frustration, and when you’ve said all that, it suddenly rises up, spreads out to a mile wide, engulfs your crops and lays waste your farms.
Its name is as flat as its appearance, the South Platte, yet for a while it was the highway of empire. It was the course of stirring adventure and the means whereby the adventurers lived. Once mighty enough to help build a continent, it is now a mean, pestiferous bother.
“I swear to God, sometimes you can tell where that damned river is only by spotting cottonwoods that line its bank.”
“You’re right, and those useless trees drink far more of the water than they’re entitled to.”
CAUTION TO US EDITORS. Last April, when we started this project, I half warned you on the telephone that my investigations might wander somewhat far afield. But “I could not imagine how provocative the history of this little town would prove to be, how involved I would become with the land, the animals, the people. And certainly I did not anticipate that to report to you properly, I would need to start with the origin of the earth.
When you face the problem of dating that origin, you will have to bite the bullet. What I have given you is based upon an earth age of 4,750,000,000 years plus or minus 50,000,000. This is the latest specific estimate I have been able to uncover and is based upon the summary studies of G.R. Tilton and R.H. Steiger, who did analytic work on the Canadian Shield, using lead isotopes.
I have consulted with the leading scientists at Colorado School of Mines, Colorado State and Colorado University and they tend toward a somewhat lesser age. You would not be far wrong if you used 4,600,000,000. You may find it useful to have the principal historical estimates:
YearAuthorityProposed Origin of Earth
1642John Lightfoot,9:00 A.M., September 17,
professor of Greek 3928 B.C.
1658James Ussher, archbishopOctober 23, 4004 B.C.
1860John Phillips96,000,000 BPE
1869Thomas Huxley100,000,000
1892T. L. Wallace28,000,000
1892Sir Archibald Geikie680,000,000
1897Jacob Johannes Sederholm40,000,000
1897Lord Kelvin40,000,000
1899John Joly100,000,000
1907B. B. Boltwood1,640,000,000
1917Joseph Barrell1,600,000,000
1947Arthur Homes3,000,000,000
1956C. C. Patterson4,550,000,000
1960Tilton and Steiger4,750,000,000 ± 50,000,000
My own educated guess is that before long we may be tending toward some date like six billion years, but I would not recommend that you stick your neck out in that direction till more studies are in. My figures will prove consistent if you settle upon Tilton and Steiger’s 4,750,000,000, which is supported by recent moon data.
As to my datings of classical geologic periods, I have followed the most conservative and generally agreed-upon dates. You should have no trouble with these, as scientists the world over agree generally as to relative datings. There are discrepancies. Ogden Tweto, the foremost expert on the Laramide orogeny, believes the New Rockies began to emerge 72,000,000 years ago, with the process terminating about 43,000,000 years ago. Others have preferred beginning dates like 80,000,000 to 65,000,000 and terminal dates as late as 39,000,000.
But as to the specific relationships between the geological eras, systems and series, there can be no logical protest. The Silurian period follows the Ordovician, and the Miocene epoch follows the Oligocene as surely as Wednesday follows Tuesday. What the precise length of each unit was, and when the whole began, we cannot say with certainty, but we can be absolutely sure of the relative relationships.
It is precisely as if, in the distant future when written records have been lost, scientists want to determine when American constitutional government began. All they have to work on is a marble plaque giving the names of the first sixteen Presidents, the fact that Lincoln ended his term in 1865, and the law that a President was elected for a term of four years.
Washington Harrison
Adams Tyler
Jefferson Polk
Madison Taylor
MonroeFillmore
Adams Pierce
Jackson Buchanan
Van BurenLincoln
Using these data, the scientists would multiply si
xteen by four and subtract that number from 1865; they would thus deduce that our nation started in 1801, which is too late.
Then let us suppose that one clever scientist discovers that Jefferson, Madison and Monroe each served eight years. He might conclude that all did and decide that the nation started in 1737, which is too early.
Let us now suppose that another scholar finds that the two generals, Harrison and Taylor, died shortly after being elected and should therefore not count in the series. There would thus be only fourteen Presidents, each serving eight years, which would give a starting date of 1773, which is better but not yet close to the true date, which was 1789. However, regardless of the misconceptions of the scientists as they work their way through the data, they do have the proper sequence, and they are refining their judgments. American constitutional democracy started sometime around the end of the eighteenth century and could not possibly have started at the end of the seventeenth.
The Appalachians were incontrovertibly old when the New Rockies emerged; the central part of our nation did lie submerged beneath a great sea for millions of years; and volcanoes in southeastern Colorado did produce rocks aggregating some fourteen thousand cubic miles. On these established matters we can expect future refinements of judgment. But not reversal. The land at Centennial developed pretty much as stated.
Chapter 3