How a Valley Became a Mesa, and Why a River Runs Through It

The town of Golden, Colorado is right next to the foothills of the Rockies, but the most striking feature there is a mesa called Table Mountain. It's one of those utterly western-looking landmarks you would never find in the east. You almost expect to see John Wayne riding past it. Table Mountain actually has two parts--North and South Table Mountain--and the famous Coors brewing company sits in the canyon between them. Here's a picture of North Table Mountain from the foothills above Golden. You can see part of South Table Mountain on the right.

Photo by Ross Mays, from Lookout Mountain

I love hiking on top of Table Mountain, because it's like an grassy oasis in the middle of the Denver sprawl. It's surprisingly expansive once you get up there, and the view of the Front Range is spectacular.There's also another view of Table Mountain that's even more impressive, at least to me, but it's a view you have to use your imagination to see. To see what I mean, take a look at the picture below.

Photo by Ross Mays, ancient landscape drawing based on Drewes, 2008 (see that paper for a more accurate diagram)

This is a geologist's view of Table Mountain (or actually an amateur's version a geologist's view). One of the great things about geology is that it lets you see multiple landscapes all at once. You see the modern landscape, of course, but in your mind's eye you also see older landscapes superimposed on it. It's like looking at the world through goggles that let you see the contours of past worlds, and tell you how they gave rise to today's landscapes.

So what's going on in these past worlds? What's up with those volcanoes? The picture shows North and South Table Mountain from the south, from the slopes of another hill called Green Mountain. The sketches show ancient landscape features from different times in the past. They didn't necessarily exist at the same time.

To see how these ancient landscape gave rise to the modern one, it helps to start by considering the ridges of upturned rock you can find north and south of Golden, at places like Red Rocks and Dinosaur Ridge. In the picture below, you can see some of those layers where I-70 cuts though the Dakota Hogback just south of Golden (notice the man on top, walking forward in time from the Jurassic to the Cretaceous Period.)

The upturned rocks along the Front Range are sedimentary layers dating from 300 million years ago (at places like Red Rocks) to about 70 million years ago. Like all sedimentary rocks, they were more or less flat when they were laid down. They're still flat to the east of the Rockies, and buried under younger rocks. Along the Front Range, though, they turn sharply upward and emerge from deep underground. That's no coincidence, of course--the Rockies are what pushed them upright, when they first started to rise about 70 million years ago. What we don't see today, except through geology goggles, is that the same rock layers extended across the rising Rockies. These layers were pushed high in the air, where they began to erode away, exposing the harder, older granite and metamorphic rock that makes up most of the Front Range today (except for a few remnants of sedimentary rock, stranded high in the mountains).

All these geologic upheavals caused magma to rise from deep in the earth, creating the Cretaceous volcanoes sketched on the far left in the second image. These volcanoes soon began eroding, too. Together with eroded the sedimentary rocks lifted by the Rockies, they formed a layer of coarse gravel at the base of the new mountains. This gravelly rock now forms the bottom layers of Table Mountain. The volcanoes are gone, but you can pick up a piece of volcanic gravel--rounded by ancient rivers--and know they were once there. Some of the last dinosaurs once walked on this gravel as it rose, including a T rex that left a tooth behind on the future flanks of the mountain.

When that T rex was alive, though, Table Mountain didn't exist. In fact, Table Mountain began as a valley, in the Paleocene Epoch, just after the extinction of the dinosaurs.* In those days there was another volcano near the north end of a shallow valley where Table Mountain is now. It erupted four times over a period of about a million years, sending lava flows down the valley. Over time this lava solidified into a kind of volcanic rock called shoshonite. The volcano mostly eroded away, leaving a remnant known as Ralston Dike, which you can still see north of Table Mountain. The Rockies kept eroding onto the plains, and more layers of sediment covered the lava flows. Finally, the mountains were buried so thoroughly in their own debris that they were little more than hills projecting above the ancient plains.

So how did the Rockies come back, and how did a valley become Table Mountain? Like this: Just a few million years ago (the exact time seems to be controversial) complex tectonic forces lifted the entire region about a mile into the air. That's why Denver is a mile high today, even though it's on the plains. This regional uplift caused rivers coming out of the mountains to begin cutting downward, carving the deep canyons along the modern Front Range and stripping away the top layers of debris on the plains near the mountains.** This great event--still going on today--is known as the Exhumation of the Rockies.

As the great plains eroded, the sediments above and around the Table Rock lava flows eroded along with them. But when the hard volcanic rocks were finally exposed, they resisted erosion and protected the soft layers of rock below them. That's how mesas form--a hard layer of caprock on top keeps the rocks underneath from eroding. The valley had become a mesa, capped by lava flows from an ancient volcano.

But how did the mesa become two mesas, with a river (Clear Creek) running between them? Why didn't the creek go around the mountain, instead of straight through it? The answer is that Clear Creek once flowed across the old high plains, above the lava flows of Table Mountain. As it started cutting down into the plains, it encountered the hard volcanic rock. By this time, though, its course was already set--it was trapped within its own channel. So it kept on cutting downward, though the hard lava flows. Along with other streams in the area, it kept eroding the old high plains surface. Eventually, Table Mountain emerged from under the debris, with a river running though it, and an amazing story to tell.

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Table Mountain Shoshonite Porphyry Lava Flows and Their Vents,Golden, Colorado / Harald Drewes, 2008

Geology Underfoot Along Colorado's Front Range / Lon Abbott and Terri Cook


*The first epoch of the Cenozoic Period. The Mesozoic ended with the extinction of the dinosaurs. The North American boundary between these two time periods (known as the K-T Boundary) was first identified on South Table Mountain.

** There are still remnants of these ancient high plains. Interstate 80 in southern Wyoming follows one of them, called The Gangplank. This old surface of the ancient plains rises almost to the top of the mountains, which is why the interstate was built there. This is also where the first transcontinental railroad crossed the Rockies.

Is it a Good Idea to Base Morality on the Supernatural?

I had just asked the rhetorical question—which I often ask during my talk on the evolution of morality and how to be good without God—“What would you do if there were no God? Would you rape, steal, and murder?” Naturally people agree that they wouldn’t, but in this instance the man said he was pretty sure that if he decided that there were no God he would do just that. I told him Jesus loves him and has a plan for his life and future. - Michael Shermer

I'm always amazed, and slightly alarmed, when I hear people say that if there were no God there would be no reason to be moral. I saw that sentiment expressed today in an online thread. I had said I don't think laws should be based on moral codes that are solely religious in origin. Somebody then asked me:

So, why are you against pedophilia? If you are going to throw out the common moral standard based on Judeo-Christian values, I'd really like to see how you justify anything being wrong.

I thought, "You honestly can't think of any reason pedophilia might be wrong besides 'God doesn't like it'? That scares me." Here's a guy who apparently can't imagine morality without religion, and Judeo-Christian religion in particular. Similar attitudes may explain why some people, such as Phil Robertson, hear others say, "I don't believe in God" and assume they must also mean, "I don't believe in right and wrong."

Anyway, when people tell me they can't see why anyone should be moral if there's no God, I react like Michael Shermer, thinking, "Then I really hope you keep believing in God." It freaks me right out. The only reason it doesn't give me a panic attack is that I don't really believe most people would start stealing and murdering if they stopped believing in God. I'm convinced most of them would go on being the decent people they are. Still, I'm struck by often people say that if there were no God--if morality weren't in some way written into the plan of the universe--then we would have no "real" foundation for morality.

My view is the exact opposite. As far as I'm concerned, what would really make the foundations of morality shaky is for them to be dependent on the existence of God. I believe that for a few reasons*, but the most important is this: We don't know that God exists. What if it turns out he doesn't? Then morality truly wouldn't have any foundation. If most people's morality depends on the proposition that God exists, and they decide he doesn't, then they will see no reason to be moral, and we're headed for Mad Max world.**

And let's face it: God's existence is notoriously hard to prove. The universe is full of things--rocks, trees, stars, IBM, sadness, lying--that every sane person agrees exist. These things are unambiguously perceptible in a way people can agree on. God is not one of those things. We don't have actual, unambiguous evidence that he exists. You can't point a telescope at him and say, "See, there he is."

People who say morality depends on God are basing morality on the existence of an invisible, hypothetical, supernatural being. (Notice I didn't say non-existent--I don't know whether he exists or not). So when I hear them say they can't take any moral idea seriously that isn't based on God, what I hear is, "I can't take any moral idea seriously unless it's grounded in the supernatural." Maybe that's not the most charitable interpretation, but it gives an idea of how shaky it seems to me. People don't like to hear God compared to supernatural phenomena like ghosts, or auras, or Zeus, but I've seen no more physical evidence he exists than there I have that ghosts do. (If you disagree, I have a favor to ask: Don't get mad. Show me the evidence that I'm wrong. If it's convincing, I'll change my mind.)

So, if God's existence isn't a firm foundation for morality, what is? I think it helps to start by asking the following question: In what kind of universe would there be no need for morality? The answer, I think, is a universe where there are no conscious beings to value things, to experience pleasure and pain, to have hopes and dreams, and so on. If the universe were nothing but blind matter going about its business, there would be no need for one part of it to give moral consideration to another part. None of the parts care. The fact that some parts do care, and feel and hope and suffer and so on, is the reason that morality is necessary.

So how about this as a foundation for morality: the recognition that other beings have experiences, wishes, and emotions, just like we do? How about recognizing that their happiness, hopes and suffering are just as real to them as ours are to us? How about the idea that if something hurts another for no reason, then it's likely to be wrong? Or the idea that if it helps another(and doesn't cause wider harm) then it's probably good? Recognizing that other beings' experiences (I say "beings" because I think many animals qualify) are just as real as our own is the first step in acting morally. Once I recognize that the lives and experiences of others are just as important to them as mine are to me, I see that I can't reasonably expect others to treat me morally if I don't do the same for them. What makes me special?

That may seem simple enough, but nothing is that simple--especially moral questions. For one thing, you can't actually prove that someone else's experiences are as real to them as yours are to you. For all I really know, everyone on Earth but me is an automaton. Maybe everybody but me has no more sentience than a Roomba? Maybe, but I don't believe it for a minute. I can't prove that others have experiences and desires just as vivid as mine, but it's a reasonable assumption...if I have them, why wouldn't they?

Another problem with basing morality on the consciousness and preferences of other beings is that it's not that straightforward in practice. The kind of simplistic utilitarianism that says we should maximize pleasure and minimize pain has big problems. For example, it suggests that it's ethically right to kill one healthy person and use their organs to save the lives of five sick people. I don't know about you, but something seems wrong with that to me.

There are other issues with pure utilitarianism, too, but I'm not advocating pure utilitarianism, and I'm not saying that respect for the experience of others is the last word on morality. I'm saying it's the first word. It's a good start, and it's based on something truly tangible. It's not as tangible as a brick wall, but it's much more tangible than the claim that morality is built into the universe in some unspecified way, or that it flows from a hypothetical, invisible being. I am pretty sure others have the same kind of hopes, desires, pains, and pleasures that I do. I'm much less certain that there's a God, or that morality depends on his existence.

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* Among them the highly questionable ethics in the Bible (killing homosexuals, adulterers, and disobedient children, dashing Babylonian children's heads against rocks, women being submissive to men, treating the mentally ill as though they were possessed by demons, and and so on), and the Euthyphro Dilemma, which I've talked about elsewhere.

** One thing I'm aware of, and may need to think about more, is that I'm coming very close to the consequentialist fallacy here. If I said, "If people believe morality is based on God, and they stopped believing in God, then the consequences would be bad. Therefore, morality is not based on God. That's a fallacy--what comes after the word "therefore" in that claim doesn't follow from what comes before it. The fact that a claim would have bad consequences if true doesn't mean it isn't true. But this isn't exactly what I'm saying. What I'm saying is that, while the consequences of basing morality on God might be bad, it actually doesn't make sense to base it on God anyway--consequences aside. What makes sense is to base it on recognizing other people's experience as being just as real as mine. If there were no consciousness, feelings, etc., in the universe, there would be no need for morality.

Huck's Dilemma: Mark Twain on the Heart Versus the Conscience

"In a crucial moral emergency a sound heart is a safer guide than an ill-trained conscience." - Mark Twain

Today I came across the quotation above, and thought it sounded like very wise advice. It's from one of Mark Twain's notebooks, in which he reflects on the central moral crisis in Huckleberry Finn. In the book, Huck's friend Jim, the runaway slave who came down the river with him, has just recaptured--betrayed by King and the Duke, the two con artists they had been traveling with. Huck is trying to decide what to do, and as hard as it is for us today to imagine, his conscience tells him it would be wrong to help Jim. That's what he's been taught all his life. It's what they taught in Sunday school in those days. But his heart is saying something different.

Usually I do my own writing on this blog, but this time I'm going to let Mark Twain make his point in his own words. Why describe the maestro's music, if you can invite him up on stage to play?

First, here's the passage from Huckleberry Finn. It's a long quotation, but it's also one of the most powerful things I've ever read, so think it's worth it. Today Huck's reasoning and his use of the N-word are shocking to us (as they should be), but they're an accurate reflection of how someone in Huck's culture would have thought and spoke:

After all this long journey, and after all we'd done for them scoundrels, here it was all come to nothing, everything all busted up and ruined, because they could have the heart to serve Jim such a trick as that, and make him a slave again all his life, and amongst strangers, too, for forty dirty dollars.

Once I said to myself it would be a thousand times better for Jim to be a slave at home where his family was, as long as he'd got to be a slave, and so I'd better write a letter to Tom Sawyer and tell him to tell Miss Watson where he was. But I soon give up that notion for two things: she'd be mad and disgusted at his rascality and ungratefulness for leaving her, and so she'd sell him straight down the river again; and if she didn't, everybody naturally despises an ungrateful nigger, and they'd make Jim feel it all the time, and so he'd feel ornery and disgraced. And then think of me! It would get all around that Huck Finn helped a nigger to get his freedom; and if I was ever to see anybody from that town again I'd be ready to get down and lick his boots for shame. That's just the way: a person does a low-down thing, and then he don't want to take no consequences of it. Thinks as long as he can hide it, it ain't no disgrace. That was my fix exactly. The more I studied about this the more my conscience went to grinding me, and the more wicked and low-down and ornery I got to feeling. And at last, when it hit me all of a sudden that here was the plain hand of Providence slapping me in the face and letting me know my wickedness was being watched all the time from up there in heaven, whilst I was stealing a poor old woman's nigger that hadn't ever done me no harm, and now was showing me there's One that's always on the lookout, and ain't a-going to allow no such miserable doings to go only just so fur and no further, I most dropped in my tracks I was so scared. Well, I tried the best I could to kinder soften it up somehow for myself by saying I was brung up wicked, and so I warn't so much to blame; but something inside of me kept saying, "There was the Sunday-school, you could a gone to it; and if you'd a done it they'd a learnt you there that people that acts as I'd been acting about that nigger goes to everlasting fire." 

It made me shiver. And I about made up my mind to pray, and see if I couldn't try to quit being the kind of a boy I was and be better. So I kneeled down. But the words wouldn't come. Why wouldn't they? It warn't no use to try and hide it from Him. Nor from me, neither. I knowed very well why they wouldn't come. It was because my heart warn't right; it was because I warn't square; it was because I was playing double. I was letting on to give up sin, but away inside of me I was holding on to the biggest one of all. I was trying to make my mouth say I would do the right thing and the clean thing, and go and write to that nigger's owner and tell where he was; but deep down in me I knowed it was a lie, and He knowed it. You can't pray a lie—I found that out. 

So I was full of trouble, full as I could be; and didn't know what to do. At last I had an idea; and I says, I'll go and write the letter—and then see if I can pray. Why, it was astonishing, the way I felt as light as a feather right straight off, and my troubles all gone. So I got a piece of paper and a pencil, all glad and excited, and set down and wrote:

Miss Watson, your runaway nigger Jim is down here two mile below Pikesville, and Mr. Phelps has got him and he will give him up for the reward if you send. 

Huck Finn.

I felt good and all washed clean of sin for the first time I had ever felt so in my life, and I knowed I could pray now. But I didn't do it straight off, but laid the paper down and set there thinking—thinking how good it was all this happened so, and how near I come to being lost and going to hell. And went on thinking. And got to thinking over our trip down the river; and I see Jim before me all the time: in the day and in the night-time, sometimes moonlight, sometimes storms, and we a-floating along, talking and singing and laughing. But somehow I couldn't seem to strike no places to harden me against him, but only the other kind. I'd see him standing my watch on top of his'n, 'stead of calling me, so I could go on sleeping; and see him how glad he was when I come back out of the fog; and when I come to him again in the swamp, up there where the feud was; and such-like times; and would always call me honey, and pet me and do everything he could think of for me, and how good he always was; and at last I struck the time I saved him by telling the men we had small-pox aboard, and he was so grateful, and said I was the best friend old Jim ever had in the world, and the only one he's got now; and then I happened to look around and see that paper. 

It was a close place. I took it up, and held it in my hand. I was a-trembling, because I'd got to decide, forever, betwixt two things, and I knowed it. I studied a minute, sort of holding my breath, and then says to myself:

"All right, then, I'll go to hell"—and tore it up.

When I read Huckleberry Finn as a kid, the force of that passage was mostly lost on me. When I read it as an adult a while back, I felt like I had been punched in the chest.

Now let's turn to the full passage I found today, where Mark Twain is explaining how he saw Huck's dilemma (actually, he's writing to himself about what points to make in a speech on the topic).

"I should exploit the proposition that in a crucial moral emergency a sound heart is a safer guide than an ill-trained conscience. I should support this doctrine with a chapter from a book of mine where a sound heart and a deformed conscience come into collision and conscience suffers defeat. Two persons figure in this chapter: Jim, a middle-aged slave, and Huck Finn, a boy of 14. . . . . bosom friends, drawn together by a community of misfortune . . . . . 

In those old slave-holding days the whole community was agreed as to one thing – the awful sacredness of slave property. To help steal a horse or a cow was a low crime, but to help a hunted slave. . . . or hesitate to promptly betray him to a slave catcher when opportunity offered was a much baser crime, and carried with it a stain, a moral smirch which nothing could wipe away. That this sentiment should exist among slave-holders is comprehensible – there were good commercial reasons for it – but that it should exist and did exist among the paupers. . . . and in a passionate and uncompromising form, is not in our remote day realizable. . . . It shows that that strange thing, the conscience – that unerring monitor – can be trained to approve any wild thing you want it to approve if you begin its education early and stick to it.

I was tempted to let Mr. Twain end this post there, because he can write circles around me, but I've learned that I haven't always made my point as clear to others as it seems to me. So, my point is this: Mark Twain was right. The world has seen all kinds of conscience-deforming dogmas that tell people not to let compassion get in the way of doing the "right" thing. Think of the fundamentalist Muslim fathers who think the right thing to do if their daughters are raped is to kill them to preserve the family's honor--even if it breaks their heart. Think of the medieval priest trembling as he orders a "witch" to be hanged, because he honestly believes it will save others from hell. Think of the young Nazi soldier weeping--as many did--the first time he is ordered to shoot Jews. His heart is screaming "NO", but his conscience has been taught not to let compassion override the "greater good" of racial purity. Think of all the 19th century Americans raised like Huck Finn. How many of them saw runaway slaves, and sympathized with them, but turned them in anyway--because they had been told all their lives that it was the right thing to do?

Finally, think about what we might be doing today that falls into this ugly tradition. Which of today's dogmas result in an ill-trained conscience? What hurtful "moral" decisions are being made today that future generations will look back on in horror? And how many of them could still be avoided if, like Huckleberry Finn, we have the guts to go with our heart instead of our conscience?