Friday Field Photos: Folded, with Lineation

This is a small glacial boulder of folded meta-argillite, possibly from the Precambrian McCoy Creek Group, which I found along the trail between Stella and Teresa Lakes, beneath Wheeler Peak in Great Basin National Park, close to last week's boulder. The greenish, coarser-grained layers accentuate and define the folding, which otherwise would be more difficult to see in the reddish or purplish gray layers.
Zooming in on the small boulder, I'm poining at some crude lineations, which my finger roughly parallels. The green bed at the top of the boulder is also lineated.
The lineation direction theoretically defines the direction of motion present during the tectonic event that created the lineations and possibly the folding. If we had some context, if this rock was part of an outcrop, we could look perpendicular to the lineation direction, instead of parallel to it the way we are now. While looking perpendicular to the lineation direction, the nature of the folding or of other micro- to meso-scale structures might tell us relative motion of beds during the lineation-forming event, for example top-to-the-east or top-to-the-west. Because this rock was part of a glacial moraine, it could tell us very little about the tectonic events it had been exposed to during the course of the last 540 million years or so. (GSA Geologic Time Scale.)

Highway8A Introduction I

April 16, 2001—Reno, NV
About to leave for Spencer Hot Springs.
Mostly sunny, cool, breezy.

I am a geologist, and these are going to be notes that I write in little journal books I carry around. ...a whole lot of them are going to lack any structure at all, but if you know a geologist, you know that that is the way he expresses things. Notes: there is no continuity in a geologist’s life, not in an active, busy one, anyway.”
—Rick Bass, Oil Notes

When I started this book — which I've variably titled Mojave Exploration or Highway 8A depending on which section I was writing — I wrote longhand on yellow sheets of lined paper, typed stream of consciousness on an old Mac powerbook, jotted shorter notes in spiral-bound journals, kept scribbled references from myriad phone calls on torn bits of paper, and penciled carefully in one or two of the little yellow field books that geologists are known to carry around out in the field. And so I sat, one blustery spring day, getting ready for a trip to the hot springs, while at the same time trying to get started on starting, trying to write some kind of introduction or prelude to a book consisting of scattered pieces. It was my idea at the time that I'd write every now and then, as though mapping in some field area, writing notes that might go with the stories that were already partly written, but which are even now incomplete. And so I began that day with a field book, a book designed to be carried securely in the side pocket of a Filson vest while out in the field — "the field" being that great beyond where we geologists go to do our fieldwork. And so I began....

---

This field book, the one I am writing right in now, is being written from the perspective of my future; it is being written by my future self, my self as an old woman — an old geologist — an old geologist with a long memory. My long memory has mixed the past, present, and future into one package the way some geologic rock formations have been pushed, shoved, and squeezed — even sliced and diced — into stratigraphic or tectonic packages where every resulting contact between individual rock formations involves some kind of geologic activity: deposition, mountain building, erosion, folding, and faulting. Because of my geologic memory — my intricate, enduring memory — most of the things I’m writing about happened long ago when I was young and clambered over the rocks and hills freely and easily: like a mountain lion or coyote, like a desert fox. Now I’m a silver fox with the long memory of an elephant, the memory of an ancient mammoth.

Most geologists have long memories. We have to. It’s not just so we can retain enough brain cells to survive the beer, gin and tonic, and tequila sunrise nights that so often go with being a geologist, though it does help to have enough brain cells to begin with so enough will remain later. The long memories most geologists have are primarily concerned with knowing how to delve into what has been called Deep Time.

Most people think the past is gone — that it is not present, that it is not now. This now, however, becomes past before I can even say “now,” and so maybe there is no present. Whatever. What I know to be true, is that the past is not gone, at least not all of it. It’s preserved in the rocks and in the landforms of the earth. And the past will be written in future rocks and landforms that haven’t yet been born. That’s the thing about the past — or maybe that’s the thing about the “now,” or about time — it’s all present, right now, in the present. If you’ve got a long memory like I do, all of time is here now: all the time that was past, all the time that is now, all the time that will be future, and all the time that has been imagined or envisioned as future but has not yet, and maybe never will, come to pass (see Dark Side of the Moon).

Geologists routinely work with the long, well-written, though sometimes buried, obscured, offset, or even truncated memories of the earth. Geologists work with all of geologic time: past, present, and future. For example, because of my particular geologic knowledge and experience, I could write a book called Ore Deposits of the Near and Far Future, the way some geologists write about earthquakes or volcanic eruptions yet to come. Instead, I’m writing these field notes about that long ago past. I’m writing them because I dreamed of doing so one summer day in the early 1980’s while I was driving south on Nevada Highway 8A — south from The Frontier, a place that no longer exists, toward a cabin in Kingston Canyon, where I no longer live — driving on the longest north-south straight stretch of paved Nevada road, on a highway that no longer bears its original number. On that long-ago day I dreamed of this book, and so it has come to be: that long ago past is present now, just as this now was present then.

---

And that's the way I began back then, in the spring of 2001, in a fit of fancy.

Related Posts:
Why Highway 8A
Single Digit Highways
A Bit about License Plates
Highway 8A: The Cutoff from Cedarville to the Winnemucca-to-the-Sea Highway

Related Asides:
A Geologist's Field Book
Deep Time
Dark Side of the Moon
Wedge #15: Ore Deposits of the Future

Deep Time

Deep time, geologic time, and the geologic time scale are intertwined concepts relating to the age of the earth, the long epochs, periods, eras, and eons of earth time, a time that is so long compared to our ordinary, everyday time, or even to historic time, that it took some number of years for it to be recognized. We in the west were formally introduced to geologic time by James Hutton, the father of geology. In Theory of Earth, published in 1788, he said:

For having, in the natural history of this earth, seen a succession of worlds, we may conclude that there is a system in nature; in like manner as, from seeing revolutions of the planets, it is concluded, that there is a system by which they are intended to continue those revolutions. But if the succession of worlds is established in the system of nature, it is in vain to look for anything higher in the origin of the earth. The result, therefore, of this physical enquiry is, that we find no vestige of a beginning,—no prospect of an end.

The Persian polymath, Avicenna, had come to a similar conclusion more than 700 years before Hutton:

Either they [mountains] are the effects of upheavals of the crust of the earth, such as might occur during a violent earthquake, or they are the effect of water, which, cutting itself a new route, has denuded the valleys, the strata being of different kinds, some soft, some hard... It would require a long period of time for all such changes to be accomplished, during which the mountains themselves might be somewhat diminished in size. [quoted by Toulmin and Goodfield, 1965]

John McPhee took us a little deeper in 1981, when he introduced the phrase "deep time" as a proxy for geologic time in his book Basin and Range. Prior to that, geologic time was the realm of geologists; since then, deep time has become a part of our everyday vocabulary. John McPhee, in essence, gave geologic time to non-geologists.

As a geologist, I've studied geologic time at least since high school, when I took Earth Science as an elective, extra science. I knew of geologic time prior to that, going back possibly into my early or middle childhood, when I became fascinated with rocks, minerals, volcanoes, trilobites, and dinosaurs, and when I probably learned some of the names of the geologic time periods and eras, such as Cretaceous. (Wikipedia shows the ages, epochs, periods, eras, eons, and supereons of the earth better than the geologic time scale linked to earlier; also see the ICS Geologic Time Scale). Did I understand the vast amount of time involved between trilobites and dinosaurs? I don't know.

I do know that thinking in terms of geologic time has become somewhat commonplace for me, and it seems to be primarily a matter of numbers and scale, and something that I visualize. My life fits inside a linear view, which runs from left to right in front of me: my birth being to the left, today being right in front of me, and my imagined latest years, even somewhat beyond likelihood, being to the right. When I think of history going back to the time change from B.C. to A.D., 1 A.D. is on the left, and everything else is relatively squished as it approaches today, which is still right in front of me. So, what about the 2 million years or so of Pleistocene glacial and interglacial intervals? Now, I've placed the beginning of the Pleistocene over to the left, our general time or the last century is right in front of me. At this point, I can't help but look farther left, beyond the beginning of the Pleistocene, where I can easily see the entire Tertiary back to 65 million years ago.

If I think of all of geologic time — the time frame during which the Earth existed, the last 4.6 billion years — things get even more squished on the end towards our current time, and I've often at this point managed to seat myself firmly in the early Paleozoic, Cambrian maybe, about 600 million years ago. The Precambrian is off to the left, and everything else off to the right. Sometimes I look at this sliding geologic time scale from the end of the Paleozoic, toward the Mesozoic, knowing (even though the Paleozoic rocks and fossils didn't know) that dinosaurs and the massive intrusions of the Sierra Nevada will be coming along as geologic time progresses.

And so, viewing all of geologic time, or particular parts of geologic time, requires me to slide my view to the right and left — or to slide time itself — while expanding or contracting the detail of the time frame, depending on what I want to look at. And when I'm reading about a particular time — whether historic, pre-historic, or geologic — the view often shifts until that the particular time is right in front of me, with time after that, including present time, over to the right.

Another thing I find myself doing when trying to view geologic time — and possibly this happens because I've read so many science fiction books set in countless future timelines — is to include future histories and future geologic time frames in my view, way off to the right. I do this when thinking about the future of the Earth, Solar System, and Universe, and also when thinking about things happening on Voyager in the 24th century (Star Trek timeline), or on the planet Path (Ender’s Universe). Often, this future time looks dark, with a lot of scattered stars and star systems. Or, once again, if I'm reading or watching books or movies set in these future timelines, that present is right in front of me, and our current present — their past — is to the left.

Some time ago, I read In Search of Deep Time by Henry Gee. Early in the book, he gets into a description of deep time, based in part on what John McPhee said in Basin and Range:

McPhee meant the term to refer to the immense intervals, measured in millions of years, disccussed as if they were days or weeks in the conversation of geologists: yet in reality, the intervals of geological time are too long to be readily comprehensible to minds used to thinking in terms of days, weeks and years--decades, at most.

He goes on, after showing a standard geological time chart:

But apart from telling you that Deep Time is long, conventional accounts never consider the implications of the scale of Deep Time on the way we think about evolution [I extrapolate, here, to include other geological occurrences and events]. If, as McPhee says, Deep Time implies intervals more or less incomprehensible to humans, we are entitled to ask whether it is valid to tell stories about evolution according to the conventions of narrative or drama. If it is not, then every story we tell in which causes are linked with effects, and ancestors are linked with descendants, becomes questionable: we can no longer use Deep Time as a backdrop for the stories we tell ourselves about evolution, and how and why we came to be who we are.

Once we realize that Deep Time can never support narratives of evolution, we are forced to accept that virtually everything we thought we knew about evolution is wrong. It is wrong because we want to think of the history of life as a story; but that is precisely what we cannot do. This tension--between Deep Time and the everyday scale of time--is the theme of this book. – Gee, In Search of Deep Time, Introduction

I didn't really find or feel much of that tension when reading his book, and was really looking forward to reading something deeper about deep time. The book, instead, is primarily about certain mechanical aspects of evolution (cladistics), which are really beyond me as a hard rocker, but which were nevertheless fascinating. I can't really comment as to their usefulness, but can refer you to this New York Times review of the book. As a geologist, I disagree that geologic time intervals are too immense to be comprehended. Perhaps it's a conceit for me to think so. Perhaps it's as McPhee says:

Geologists, dealing always with deep time, find that it seeps into their beings and affects them in various ways. ... In geologists' own lives, the least effect of time is that they think in two languages, function on two different scales. – McPhee, Basin and Range

Now, as an aside, I'd like to take deep time in literature farther back than John McPhee, to the "deeps of time" of J.R.R. Tokien.

Quotes from Tolkien on the deeps of time:
Out of the shadows the hobbits peeped, gazing back down the slope: little furtive figures that in the dim light looked like elf-children in the deeps of time peering out of the Wild Wood in wonder at their first Dawn. – The Two Towers, Book III, Chapter 3 [quoted here]

In this elvish sheath dwells the Blade that was Broken and has been made again. Telchar first wrought it in the deeps of time. – The Two Towers, Book III, Chapter 6 [referenced here]

And She that walked in the darkness had heard the Elves cry that cry far back in the deeps of time, and she had not heeded it, and it did not daunt her now. – The Two Towers, Book IV, Chapter 9

As it drew near the great furnaces where, in the deeps of time, it had been shaped and forged, the Ring's power grew, and it became more fell, untamable save by some mighty will. – The Return of the King, Book VI, Chapter 1 [quoted here]

A Few References:
Al-Rawi, M.M., and Al-Hassani, Salim, 2002, The Contribution of Ibn Sina (Avicenna) to the development of Earth Sciences: Foundation for Science, Technology and Civilisation, Publication 4039, 12 p.

Avicenna (Ibn Sina), c 1014-1027, The Book of Healing: editions of the Arabic text were published in Cairo, 1952-83, originally under the supervision of I. Madkour (list of works).

Gee, Henry, 1999, In Search of Deep Time: Beyond the Fossil Record to a New History of Life: The Free Press, New York, N.Y., 267 p.

Hutton, J., 1788, Theory of the Earth: Transactions of the Royal Society of Edinburgh, vol. I, Part II, pp.209-304, plates I and II. Hutton's work is available online in several places (Univ Wisconsin, 1788 version with link to 1785 abstract, Project Gutenberg, 1795 version) and also for sale at Amazon.com.

McPhee, John, 1981, Basin and Range: Farrar; Straus & Giroux, New York.

Toulmin, Stephen, and Goodfield, June, 1965, The Discovery of Time. New York: Harper & Row. [Reprinted Chicago: University of Chicago Press, 1977, 1982.]

More Reading:
Mapping Deep Time (deep time, geologic time, and Hutton)
The "Army of Caterpillars" Tracked Down (Hutton and Dutton)

NOTE: You can now, starting today, follow @GeologicTime on Twitter to find out, "What would 4.6 billion years of Earth history look like [when] represented by one year's worth of tweets?" I suspect that @GeologicTime will be quite busy during the latter months of the year! Read a little more about that project here.

Related Post: Links: Deep Time and Time

Twelve Months of LFD (2010)

As per usual (see 2008 and 2009), I'm doing the year-end meme showing the first sentence of the first post of every month, along with - for LFD - the first photo if there happened to be one. Seen everywhere, especially at VWXYNot?, Dreams and hopes of a (former post doc) scientist, There and (hopefully) back again, and Thus Spake Zuska. The rules for this meme are simple, as explained by DrugMonkey: Post the link and first sentence from the first blog entry for each month of the past year.

January
It being the start of a new year (the year 2010 to be precise), I have a few deep-time links for all you deep-time lovers (or would that be lovers of Deep Time?):

• The 2009 Geologic Time Scale: GSA
  
  ...


• Hutton's geology: ‘No vestige of a beginning – no prospect of an end’: OpenLearn
  
  [no end of sentence in the long link list was detected upon review]

February
Here, in non-chronological order, are a few of the geoblogospheric posts that have caught my eye recently.

March
The March, 2010, version of Where in the West (WITW) is really just an excuse to post a glacier picture or two.

April
Just a quick preview of a roadcut on Highway 36 near Susanville, CA, showing a basalt flow over some white [probably tuffaceous] lake sediments. The reddish baked zone may might include subaerial deposits.

May
Callan Bentley at Mountain Beltway has had a couple posts up recently about mud cracks.

June
Three years ago today, while driving between somewhere and somewhere else, I came upon this cool oasis in the greasewood zone below the sagebrush steppe on the northeast side of Honey Lake, CA.

July
I took a road trip last week, south into Big Smoky Valley (MSRMaps), in order to grab a few photos from areas I visited in 1976 while on my thesis hunt.

August
I just returned from a mega-trip with MOH into central Oregon, where I met with family at an annual reunion-type affair on a basalt-capped bluff overlooking a small Oregon town.

September
I've been working on a Highway 50 roadside geology series for quite a long time, and have managed to get a few posts in every now and then, but have many more to go before I really consider it complete (could it ever be complete?).

October
Where in the West, if you might remember, features some [unknown] location in the western part of the northern hemisphere.

November
Ophir and Out ... well, to Middlegate, anyway.

December
And so, following on from the post "What is a Road Song," here is the essence of one of the three road tapes I made in the late 1980s.

Everyone who blogs is tagged for this meme.

Why Do I Like Geology

I’ve been asked to say what I like and don't like about my work or my life as a geologist.

--SIDE NOTE: I don’t often call myself a scientist, but I call myself a geologist, which I've heard is supposedly some kind of scientist, though I wonder some days, or maybe I just wonder about some people. Whew!--

These are questions that I’m rarely, if ever, asked in real life. What I’m usually asked is, what do you do as a geologist, because most people—as far as I can tell—don’t have the vaguest idea what a geologist does. When I’m asked that, I say vague things like, I map the geology out there, you know, the rocks (because I’m a rock person). Sometimes I’m asked—by people who have an idea of what a geologist might do, and who know that I work for mining companies—how is it that you find gold or whatever-it-is you’re looking for out there. Well, then I mention mapping to find out what is out there, drilling to delineate and define the ore, and looking for various hints and clues that depend on the commodity and ore-deposit type that I might think is worth looking for (or for which someone has paid me to look, if I haven’t had the chance to decide that for myself). I explain that some things look good because of past associations: certain colors in the rocks, certain types of brecciation, certain minerals, certain structural conditions, and possibly things like quartz veins if one happens to be trying to find a vein-type deposit—but maybe even if one isn’t, because quartz veining can indicate that something is going on in the area, some mineralization processes may have been at work.

And I explain that, really, to understand these things, to discover something undiscovered or to further delineate something already discovered but not yet large enough or good enough for anyone to want to come in and mine, that I or someone will have to sample the rocks, because assays and geochemical analyses need to be performed; these are necessary so I can tell what is really in the rocks and not just end up going on past associations. Past associations can lead you in a right or wrong direction, and that direction may just depend on blind luck. So samples are necessary, geochemistry is required.

And then I explain that I’m often working on a drilling project, whether it’s an early stage drilling project nearly immediately following the mapping and sampling phase or whether it’s an intermediate or end stage drilling program, where a mineral deposit of some kind has already been discovered or even partly drilled out. And that, once again, many samples with assays and geochemistry are required. Because, although a really good geologist can estimate copper grade in some kinds of deposits, gold grade is quite elusive, even in vein deposits where some of the gold might be quite visible.

So, what is my most favorite thing? The problem I have with this question is ultimately my problem with having favorites. I used to be asked to say what my favorite color was. I had to make that up. Because, really, I didn’t have one. I like, and have always liked, a hell of a lot of colors. Some not so much, most quite well. For a while I really liked lavender, and then I decided to have blue as a favorite color, perhaps as a reaction against the ubiquitiously female pink. At some point I decided that I didn’t like green—that was after living on the east coast where all the overgrown vegetation was obscuring my view of the geology. Now, there really aren’t any colors I dislike completely, although there are several that I favor, including magenta, various shades of purple, and some shades of green—among many others.

So again, what is the thing I like best about my work or my life as a geologist? I think primarily I like or even love rocks. I like working with them, I like being around them (they don’t talk too much, for one thing), and I like trying to figure out what they’ve been doing all the many eras, eons, and epochs that they’ve been in existence—depending on their geologic age. I also love the concept of geologic time, now popularly called deep time, and I’ve loved it for a long time (for me, that is—geologically speaking I’ve loved the concept of deep time for barely an instant). The rocks don’t even really have to be consolidated or rock-like, yet, for me to like or love them. Unconsolidated materials—soil, alluvium, gravels, sand—these are all rocks in the making, although many of the unconsolidated deposits won’t be preserved for future geologists to look at, but some of them will. And when I’m working with these unconsolidated materials, deposits, and formations of Anthropocene, Recent, or Pleistocene age—which I have mapped in some detail, and even drilled when needed—I often think about whether these particular deposits will get preserved and someday become rock, as though becoming rock is the primary purpose of being a deposit of any kind. (Yeah, maybe that’s weird, but that’s where deep time meets future time in my mind.)

So, now we’ve established what I like best—and because I like rocks best, and because I'm an exploration geologist looking for minerals, a few things become required, whether I like them or not. These requirements generally include that I travel for work, because one usually runs out of backyard rocks fairly quickly, and because the mineral deposits I'm finding, mapping, sampling, drilling, and delineating aren't usually found in my backyard (somone's backyard, maybe; if they had been found in my backyard, I'd alreay be rich and would just be blogging and traveling for a living).

Traveling, therefore, is a requirement. There are jobs that don’t require quite as much traveling; these are usually at or near mines. Some of these jobs require long commute times, and they usually require long working hours. By long commute, I mean as much as 2 hours in one direction. For compensation, the pay is often good, and sometimes the time off is good. Also, because travel away from home base is often required (except sometimes when working at mines), staying in motels becomes almost second nature. It used to be something I didn’t like, something that for some unknown reason even made me anxious. Now it’s nice to get away, at least for a while, and one reason that's so is that the rooms are almost always clean and not cleaned by me, and they have a greater feeling of space than the little house I currently live in.

And what do I dislike about the life? (Yes, we call it that: the life, like we were in the mafia or something.) That can depend on a particular job, but one thing that can be bothersome is office-type politics. Traveling away from the office, if one happens to have an office, gets one out from under the keen eyes of sometimes overbearing or over-managing bosses, gets one away from gossip and other related office antics, and can allow one the freedom to do one’s job properly. In the wide open spaces, one can feel free—even in these days of constant “on” required by cell phones and such, especially because cell service is not available in many prime exploration areas—unless one happens to be close to mines, freeways, major cities. Of course, by Nevada standards many of the “major” cities I’m referring to are quite small. Which is another good thing, for the most part.

What I have found over the years is that almost all good things have their downside in some circumstances, that good things become bad things, maybe just with repetition, maybe just because of the oppositional nature of things—and likewise for bad things. The things I don’t like under some circumstances can become things I like under other circumstances, and the things I like can become things I don't like, at least for some time being.

As far as using the things I like to motivate myself through things not liked: yes, I think I do that to some extent, but in some situations I’m more likely to motivate myself with things that arean’t strictly work related, by finding something that keeps my mind entertained or keeps me inspired. These things might be as simple as taking photographs when there is time, or finding something at work that I can do that is both helpful and personally rewarding, even though it might not be required or expected. And then other times I just plow through, knowing that mineral exploration is quite variable by nature, and that I’ll be doing something else soon, maybe tomorrow, maybe in a few months—but soon in the long scheme of things, and instantaneously by the standards of geologic time.

scientiae-carnival

What is Continuity?

I am a geologist, and these are going to be notes that I write in little journal books I carry around. ...a whole lot of them are going to lack any structure at all, but if you know a geologist, you know that that is the way he expresses things. Notes: there is no continuity in a geologist’s life, not in an active, busy one, anyway.”

—Rick Bass, Oil Notes

This blog post, a submission for the March Scientiae Carnival, will explore the topic of continuity. Scientiae is facing a problem in continuity — will it continue or not — which is one reason why the topic is so appropriate. Bear with me: I'm a geologist, I may meander a bit.

For the hell of it, I'm currently searching "My Documents" for files that have the word "continuity" in them. I'm doing this for a specific reason: I think I've written about this subject before; but also for a more general reason: to see how often I've used the word. Found: ten files.

"Perhaps the process of individuation is not the same for everyone. Perhaps some people individuate through becoming something different from their parents, more so than I am from mine. Perhaps not, though — maybe I underestimate our differences sometimes and overestimate our similarities other times. Right now, I like the sense of stability and continuity I find by seeing myself in my parents, even though I have spent much of my life — and even much of the past four years — trying to be different." (1995)

"...a life buttressed by the strength and continuity of the granite of the Sierran batholith, which looked down on the valley from the east, forming the backbone of my early life." (2000)

"And maybe there is more continuity in my life than [Rick Bass] is referring to above. Maybe." (2004)

"I think that some of the continuity in a geological career or in a geologist’s life comes through seeing old places again and through watching/seeing/knowing where former colleagues are working.... This knowledge can be obtained by following the movement and careers of other geologists (engineers, techs, miners, et cetera) and by following the evolution and history of certain properties, projects, and mines. One can also follow the status and changes in mining and exploration companies in general. So, I think there is continuity after all, despite what Rick Bass said in that one book of his...." (2007)

"Further work is recommended to test for continuity and thickness of this deep zone, and to see if it shallows to the east or south." (date withheld)

So, is there no continuity in a geologist's life, especially if the geologist is an exploration geologist of some sort? It's true that one rambles and roams from place to place, town to town, prospect to project, company to company — but is there a larger, greater sense of continuity somewhere? Sometimes, I'm really not sure. When I first read the words by Rick Bass, quoted at the beginning of this meander blog post, I felt that despite certain breaks, disruptions — fault lines in my life — that there had been a certain continuity, which I described earlier as the remembering or revisiting of continuous life aspects, for example people. I think I was referring to something larger than that, though, but am not sure I can describe what I really meant.

When I think about continuity, I first have to say that my parents have been a constant in my life: they have provided a backdrop to what I've done with my life through all these many years. And yet I know that they will not always be here sharing my life with me, even if from afar by phone, through visits, and through email. And when I think about that, I feel sad. But as I write that, I also realize that the constancy in this one aspect of my life is larger than it seems: despite an anticipated future in which they are no longer here, they will still, in some way, provide a backdrop or internal place of permanency inside me for what I will do in the future. They will always be part of me; they will always be here. That is one sense of continuity, although that sense is also combined with a similarly large sense of discontinuity.

Geologists of the exploration persuasion (and many geologists of other persuasions) are always looking for (and sometimes finding) continuity between this outcrop here and that one over there, a correlation that will provide an understanding between two spatially distant areas. Once a correlation is found between these two outcrops — no matter how distant they are — a certain geological understanding might come about. For example, one might then realize that these distant outcrops represent the same moment in geologic time. This type of continuity can easily arise when the rock type and rock formation at the two distant outcrops are the same (for example the Ely Limestone of Pennsylvanian age). You might see identical and very specific fossil assemblages in the two outcrops, an indication that the two outcrops are from the same bed or geologic horizon; you might see other geologic indicators hinting at correlation, such as specific types of chert nodules; and you might notice that the particular bed is overlain by another diagnostic bed and underlain by even another diagnostic bed, if you are very lucky. You might then realize that you are seeing the same bed at both exposures, and you will therefore come to realize that you are looking at practically the same time in geologic history in both places. You've just found continuity in time across spatial distance by correlating two outcrops of one specific cherty limestone bed containing a particular key fossil or set of fossils. [This may be a rather meandering way of explaining part of the stratigraphic principle of lateral continuity.]

Another way in which you might, as a geologist, recognize continuity in geologic time across outcrops separated by spatial distance, is to find a correlation in key fossils from a particular geologic time interval, even though the two outcrops in question are of different rock types. Here we have a concept that's slightly more complex, but one might find the same trilobite in a Cambrian shale in this area over here and find the same trilobite in a Cambrian limestone some tens of miles (or more) away.

Another example of this second type of geologic continuity would be what happens with correlation of tephra beds: a resultant volcanic ash layer or bed that is deposited after one particular volcano erupts ash during one single volcanic event. An example would be the eruption of Mt. St. Helens on a particular day in 1980: on May 18th, 1980, Mt. St. Helens ash was spread far and wide across the northwestern U.S., and where it is preserved as a layer, one can identify that particular day in geologic time. Another example would be the eruption of the Mazama Ash from Mt. Mazama (now Crater Lake) on an unknown day about 7000 years ago. That ash was blown even farther and wider across the western U.S., and it was deposited in a recognizable layer and preserved in more than one kind of geologic environment. One can correlate that particular moment in geologic time from clayey lake sediments in southeast Oregon to rocky talus deposits in central Nevada. The geologic formations are different, they are separated by a distance of hundreds of miles, but those different geologic formations — a lake bed in Oregon and a talus slope in Nevada — were forming at exactly the same time. That's demonstrable geologic continuity between dissimilar geologic formations. These particular geologic beds — lake clay and talus — may not survive to become parts of future rock formations, but maybe they will.

Another way that geologists find continuity in the field, is to walk out contacts between particular rock formations from outcrop to outcrop, mapping them on paper and with GPS. Geologists map the correlation between rock formations, fault exposures, and mineralized zones this way: by mapping them in the field, by following them on the ground from outcrop to outcrop. The continuity an exploration geologist looks for will often be a speculative one during this mapping phase, one that will be later proven — or disproven — through drilling. The mineralized area might be continuous for hundreds of feet or even miles; this is a kind of spatial continuity that is required for mining. It's good, also, to find continuity in assay grade and in other economic parameters such as metallurgy. I look for these kinds of continuity while prospecting, I try to predict and project these kinds of continuities when mapping, I sometimes prove these kinds of continuities by drilling.

When I once again think about continuity in my life, I really have to go back to basics. I know that in some ways I am the same (or at least similar) to ways I was in the past. Certain characteristics will, perhaps, be found within me throughout my life. I have an experience of continuous (or mostly continuous) memory from one point in my life to another — a seeming persistence of myself through time — but I also know that I have changed through that time, sometimes profoundly. I wonder then — when I think of my life, my character, myself as containing a certain kind of continuity — am I deceiving myself?

So I go even farther back, back to basic basics. And I think that geology itself is something continuous in my life: it goes back to an early time in my life, if one considers geology to include my early childhood interest in rocks.

I am a geologist. I was a geologist. I will be a geologist. I will always be a geologist.

I have been other things, I have done other things, but there is something basic about being a geologist that will stay with me no matter what I might do in the future. For one thing, I will probably always have rocks in the house. If I clean them out, I just make space for new rocks to come in. It happens every time I remove various rock piles scattered from truck to garden to living room to garage. It doesn't seem to matter what I'm doing with my life at the time — geology, art, travel, school — a new and interesting rock will somehow work its way into my house, often when there isn't really room, and sometimes when I'm not really looking.

I often, however, have a hard time seeing the day-to-day, year-to-year continuity in my life. My outward activities change, my jobs change, the places I go for work change, the people I work with change. Perhaps it's easier to see continuity when one is younger. Perhaps continuity is really an illusion, something I create in my mind in order to feel something solid, something dependable, something constant, something rocklike in myself and in my life.

I am a geologist. The rocks, the earth — they are always the same. See how they don't move (except during those occasional events like earthquakes, volcanic eruptions, and landslides). See how the landforms and topography of even geologically active areas remain solid enough and constant enough that we can use topographic maps made in the 1970's and earlier — at least for most of the basics. But because I am a geologist, I know that all those statements are exactly and precisely incorrect. The rocks and the earth, the landforms and the topography do not stay the same, no matter how much I think they do, no matter how much I wish they would. The topographic maps of the 1970's and before show identity of topography until you come down to the details that are changing day to day and year to year. The stream beds have moved. The talus slopes have creeped. Lava flows have massively changed the topography in Hawaii, and they do so on a daily and yearly basis. Shorelines and barrier islands have moved. Deltas have changed their shapes. Rapids in canyons like the Jarbidge and the Grand have changed: they move, they increase, they diminish. New rapids form. Old ones disappear. Nothing is the same; the only constant is change.

Mountains like the Sierra Nevada, rock solid and made of granite, always give me a feeling of continuity. The Sierra Nevada in particular has provided some sense of structure and constancy in my life since I can remember. I was not born near them, but grew up with them looming above me. I have lived more than 3000 miles away from them, and they have even then been part of my life. They are there; they provide a sense of where I am, a sense of location, even when I can't see them across the many mountains of the Great Basin. When I am in Alaska, there they are, miles and miles to the southeast. When I am on the East Coast, there they are, miles and miles to the west. They are always there. Through my life, they have always been there. It is, thus, easy for me to extrapolate back in time to think that they have always been there — and they have been there for a very, very long time, but not forever. It is also easy for me to extrapolate into the future and find no future in which they don't exist. In my lifetime, they will always be there. In the geologic history of the far future, they will be there as mountains for a very long time. Even after they are no longer mountains, but are plains with an occasional granite knob sticking out through future sediments that have long since buried them, they will be there as a geologic province for a very, very long time (look at the ancient Appalachian Mountains, no longer the same as they were when first a mountain range akin to the Sierra Nevada, yet still, hence these many geologic eras, well-recognizable as a geologic province). Someday, however, every trace of the Sierra Nevada will have been subducted into the mantle by some future, yet-to-form subduction zone. They will not be there forever. They have not been there forever, no matter how much I'd like to think so, no matter how much I wish they were and will be. Even this one rock-hard, granite-solid seeming constant in my life isn't. When I think about continuity, at least today, I find little, maybe none. I find that sad, and yet, there it is.

Continuity: I get up in the morning at about the same time every day, I make the bed and turn on the computer, while the computer is turning itself on I make coffee. I heat my cold cup with hot water, I take the coffee to the room and start up my internet connection. I sign in to Blogger and open up my main blog page, I check the weather on one to three websites using two to ten weather subpages, I turn on or sign in to one or more social network sites and check them, or not. ... No matter what my current state of life is, I find or set up some kind of routine. The routine provides me a sort of comfort, but it doesn't provide any real continuity.

Photos from Wikimedia:

• SierraEscarpmentCA
• Middle_Cathedral_from_The_Nose.

scientiae-carnival

Links: Deep Time and Time

It being the start of a new year (the year 2010 to be precise), I have a few deep-time links for all you deep-time lovers (or would that be lovers of Deep Time?):

• The 2009 Geologic Time Scale: GSA



• No vestige of a beginning, no prospect of an end: Hindered Settling, Mar 2007



• The Geologic Time Scale is Mind Boggling: Edward de Leau, May 2007



• How the Discovery of Geologic Time Changed our View of the World: ScienceDaily, Sep 2007



• "We find no vestige of a beginning, no prospect of an end": Laelaps, Oct 2007



• Time: All The Rage, Feb 2008



• The times they are a-changin': Laelaps, Apr 2009



• Time Almost not Beyond Imagining: Recent Volcanism on the Colorado Plateau and Deep Time: Geotripper, Aug 2009



• Fading Into Insignificance: Mather Point, Grand Canyon National Park: Geotripper, Dec 2009 - this is a great use of photography and zoom lenses to create a sense of scale, which is then a metaphor for deep time, with the background being the Grand Canyon, a perfect example of deep time!



• Deep Time: SERC at Carleton College



• Mapping Deep Time: About.com: Geology



• Understanding Deep Time: Boulder Area Sustainability Network (BASIN)



• Hutton's geology: ‘No vestige of a beginning – no prospect of an end’: OpenLearn

Happy New Year!

Accretionary Wedge #18: How did I Become A Geologist?

It's time for the July Accretionary Wedge, #18, which is being hosted by Volcanista over at her Magmalicious Blog. As she says, it's all about inspiration: who, what, where, when, and even how. [Photo taken from the shoulder of Wheeler Peak, looking north at the Snake Range detachment fault.]

So July’s topic is about your inspiration to enter geoscience. Was it a fantastic mentor? Watching your geologist parents growing up? A great teacher, or an exciting intro field trip? How did it happen?

The short version: I started out fairly early with an interest in rocks, minerals, mountains, and roadcuts because of travel with my geologist dad. I also fell in love with dinosaurs and volcanoes by the time I was five.

A slightly longer version: I didn't plan on being a geologist while growing up, although I collected rocks and minerals and diligently labeled and categorized them. I took Earth Science in high school, but by the time I got to college, I thought geology was out because of how lousy I was sure I'd be in Chemistry and maybe Physics. Math was fine, but I was afraid of Chemistry, and although I did fine in high school physics, I didn't think that accomplishment would have any bearing on how I'd do in college physics.

So, not knowing exactly what to take, I signed up to be a History major. I had always wanted to be the sort of person who knew the dates of important events and other historical details, and I thought that wanting to be that sort of person would be a good start. After some deliberation and a little consternation, I began my first quarter with European History. For a science, I took Geology 201, Intro Geology, a class for majors and non-majors.

The geology class - one of those huge affairs in a large, auditorium-like room with raised rows of seats - was taught by the then head of the department, Dr. G. C. Grender. It turned out that he was one of those highly inspirational teachers, who had been put in the position of teaching Intro Geology because of the number of converts he routinely would win.

History was boring. Geology was exciting. Because of my at-home geological background, coupled with my Earth Science course in high school, I had a head start on identifying rocks and minerals, and a head start on memorizing the Geological Time Scale, which of course looked a little different back then. I could also read road maps and topo maps, and I knew what a drumlin was. Before the quarter was over, I changed my major to Geology. I got a B in Euro History, an A in Intro Geology. (I later got an F in one quarter of Chemistry, and did fine in Physics. And even though I was able to skip two quarters of first year math based on high school grades and SAT scores, I managed to get a D in one quarter of 2nd year math. Things like grades eventually don't matter.)

One long version starts like this, "How did a nice girl like you become a geologist, anyhow?" I was often asked this question, especially in my early days as a geologist, often by strangers — people, usually men, who I had just run into out in the field: prospectors and would-be prospectors, landowners, ranchers, and other geologists. Really, you'd think people could be a little more inventive than to reuse this worn phrase so many times — from Yuma to Gabbs, from Hog Ranch to Okanogan, and from Juneau to Fairbanks.

I've been from Tucson to Tucumcari
Tehachapi to Tonopah

I'm Willin', written by Lowell George
Seatrain, 1970

(An applicable song: my exploration travels have taken me, on legitimate business, to all of the places mentioned.)

The question, phrased so redundantly, seemed to imply some wrongness: wrongness in my choice of careers, wrongness in my where-ever-it-was location in the field, and wrongness in the fact that I'd somehow managed to meet the questioner out in the field at all—a "field" where I presumably didn't belong. I wondered at that question every time it was asked. I usually stuck to my routine answer, "My dad is a geologist," an answer that made sense to everyone and explained everything, at least to those who asked the question. It didn't really explain things to me, nor did it tell the curious or suspicious questioners much about me. ...

July Accretionary Wedge: Inspiration

To be continued...

Signs of Spring: Ravens

When out on our most recent long hike, last weekend, we decided to climb breccia hill once again, to ascend this rocky knob of Eureka Quartzite, in order to go to the arch in the upper part of the knob. If you look closely, you can see the arch: it's above a large brownish talus patch in the left center of the photo, and in the lower part of the upper ledge. For interested geologists, the Eureka Quartzite is Ordovician in age. See new geologic time chart here.
We hiked and scrambled up the slope, finally getting high enough to have this great view of our eastern Nevada town, looking south toward the southern Egan Range.
We'd been hearing a lot of raven-like croaking, and finally we spotted these two flying together, with the second bird looking like it was carrying something in it's beak. A twig for a nest?
At about that same time, and now on the upper part of the scrabbly brownish talus slope and still one ledge below the arch, we saw this large nest made of twigs and carefully placed in a protected area below an overhang of quartzite.
One of the two ravens was watching the nest from a vantage point above it, while the second raven tried to get us to move away from the nest by flying elsewhere. If you look closely, you can see that this raven is sitting on brecciated quartzite. In fact, most of the quartzite is fractured, cut by multiple sets of joints and faults, and brecciated.
The raven takes to the air, flying around in futher attempts to get us away from the nest. Unfortunately, our path to the arch - uphill and down - led right past the nest.
One raven stands on quartzite, looking at the nest partially hidden by the piñon pine.
A raven settles into the nest. We saw one of the ravens sitting on the nest as though there were already eggs present. It seems early, but is not outside the timeframe for the beginning of raven nesting.
Here's the slope above us, with large to huge blocks of quartzite, and the arch barely in view near the center of the photo. Some quartzite blocks larger than houses have rolled all the way down the hill.
From the top above the arch, we had another great view to the south.
As we descend past the lower quartzite ledge, a raven flies from the nest. The sun has gotten lower in the west, and the entire outcrop is now in shadow.

January 2009 Accretionary Wedge is Up!

The Accretionary Wedge for January, Pondering the Future of the Earth, is up at Clastic Detritus. Go read it so you know what's in store for the next 1 million plus years!

I'm a little confused about which number this is: either #15 or #16. It looks like it's going down as #15, though I put #16 on my entry, and can't change that now because it's already been linked to. Not a big deal, though - we're talking millions of years; what's a little number like 15 or 16?

The sign in the photo above is at the Rabbit Creek exit, Exit 2, on I-70 in western Colorado, not far from the Colorado-Utah border. The sign points to a 1.5 mile interpretive trail loop, the Trail Through Time, where you can hike to an old dinosaur quarry (that would be a quarry dug for dinos not by dinos!). Stop by when you get a chance! I was in a hurry to get to Fisher Towers, so passed it by this time.

Wedge #15: Ore Deposits of the Future

Exploration geologists occasionally speculate on where to find ore deposits in a future world, from 1 to 25 or more million years from now. I'm not sure why we do this; I think it's partly a natural outcome of some of the research we do, our generally or overall speculative natures, and the fact that we sometimes watch ore-deposit-forming processes in progress. It's a natural extrapolation to take processes that are occurring today, and think about what they will generate in the future.

There are many kinds of ore deposits that one could extrapolate into future times, in case anyone reading happens to plan on sticking around for a while. For example, certain erosional and tectonic processes could combine to create gold placers of the future, and here's how: take some gold veins not yet exposed at the surface, uplift them in a mountain range similar to the Sierra Nevada, and erode them into gold placers similar to the gold discovered at Sutter's Mill, California, in 1848, which led to the California Gold Rush and the influx into the west of The Forty Niners. All you need to do is identify some not-already uplifted and eroded, world-class mesothermal gold vein systems at just the right depth in just the right tectonic setting. [Mesothermal=moderate depth and temperature of formation.]

Because of all the currently active hot springs systems around the world, many of which are related to hot, molten magma at depth and cool or cooling volcanic rocks at the surface, it should be easy to put together a list of places to find gold sometime during the next 1 to 10+ million years, whenever the gold is done being deposited at depth, and whenever these future and hypothesized deposits have been uplifted or eroded to the future surface of the earth. Of course, not all our current geothermal and hot springs systems are necessarily now depositing gold - nor will they necessarily be doing so in the future - but some are and some will.

A few of the larger and better known hot springs, geothermal, and hydrothermal systems of the world come easily to mind: 1) Steamboat Springs, NV, 2) Yellowstone, WY, 3) Wairakei, New Zealand, 4) Lassen Peak, CA, 5) Iceland, and 6) Puchuldiza, Chile. Okay, well maybe Lassen isn't that huge, but it's relatively nearby if you happen to live on the west coast. Hot spring and hydrothermal waters at Steamboat Springs, NV, and Wairakei are known for active deposition of gold and related indicator elements like arsenic, mercury, and antimony.

So, what does that have to do with the future? Just this: I recommend drilling for gold in 1 to 5 million years in the Mendocino, CA, area, with 2 to 3 million years being my best estimate of the proper timing. For proper and exact placement of drill rigs, I would wait for the future, when faults and fractures controlling future ore deposits will be identifiable, and when rocks will be available for sampling. They aren't quite available for sampling just yet - they haven't formed!

The Clear Lake Volcanic Field, located north of Napa Valley, contains one of the world's largest (or the largest) producing geothermal fields, The Geysers. The volcanic field itself is very young, with volcanic rocks ranging in age from 2.2 million years old to 10,000 years old. A large felsic magma chamber sits beneath the volcanic field, and provides heat to the geothermal system. The area, I think, should be considered as potentially active as the Yellowstone area or the Long Valley caldera.

The Clear Lake Volcanic Field sits astride the famed and tectonically active San Andreas transform fault system at the northwestern end of a long chain of volcanic fields that may begin as far south as Pinnacles National Monument and the related or offset Neenach volcanic formations farther to the southeast. This series of volcanic fields become progressively younger to the northwest, except for offset portions of fields. The volcanic eruptive centers within the Clear Lake Volcanic Field have also migrated northward to northwestward, at least during the last 2.1 million years (Wood and Kienle, 1990, p.226-229).

The volcanic field in the Clear Lake area formed about 1 million years after the tectonic regime in the area switched from subduction to transform faulting, about 1 million years after what is now the Mendocino Triple Junction passed through the area. Hot spring systems around Clear Lake and The Geysers, active and inactive or "fossil" systems, have consistently deposited mercury as well as gold. In fact, the McLaughlin gold mine, located toward the eastern side of the Clear Lake Volcanic Field, is a known epithermal gold deposit formed by one of the hydrothermal systems of the area. [Epithermal=shallow depth and low temperature of formation; ignore the part of the link that says "occurring mainly as veins."]

Anyway, the short story is that the gold deposit at McLaughlin formed in a hydrothermal system that deposited gold in veins containing adularia and alunite from 0.5 to 1.0 million years ago (Enderlin, 2002). The gold deposit, therefore, formed about 2.5 to 2.0 million years after the Mendocino triple junction passed through the area, and about 2.0 to 1.5 million years after the onset of volcanic activity in the region. It was discovered and mined about 1.0 to 0.5 million years after it formed!

It stands to reason - if all variables continue to hold (and they did in some other volcanic fields along the San Andreas fault to the southeast) - that one should expect a volcanic field to begin forming in the Mendocino area in about 500,000 years, a field that might continue erupting and forming hydrothermal and geothermal systems for at least 2.5 million years after that. So I'd say - keep your eyes open! You should be ready to drill for a McLaughlin-type gold deposit in the Mendocino area in about 2 to 3 million years, give or take a couple million!

On another note, I don't know if the vineyards of Napa Valley will migrate to the Mendocino area, or not, so be sure to sample the wines now - that is, unless you want to predict the future coastal climate of the region and find gold.

A Few References:
Bailey, E.H., and Myers, W.B., 1942, Quicksilver and Antimony Deposits of the Stayton District: Geol. Survey Bull. 931-Q, 1942, p. 405-434.

Enderlin, D., 2002, Geology of the McLaughlin deposit: Homestake Mining Company published online, pages 1 - 5. Age dates cited on page 2.

Fox, Jr., K.F., Fleck, R.J., Curtis, G.H., and Meyer, C.E., 1985, Implications of the northwestwardly younger age of the volcanic rocks of west-central California: Geol. Soc. America Bulletin, vol. 96, no. 5, p. 647-654.

Leith, C.J., 1949, Geology of the Quien Sabe Quadrangle, California: Calif. Div. Mines, Bull. 147, 60 pages; including Bailey, E.H., and Myers, W.B., 1949, Quicksilver and Antimony Deposits of the Stayton District, p. 37-56.

Wagner, D.L., Fleck R.J., McLaughlin, R., Sarna-Wojcicki, A., Clahan, K.B., and Bezore, S., New constraints on the age and distribution of Cenozoic volcanics north of San Pable Bay, California: Implications for displacement along faults inboard of the San Andreas fault: [abs.]: Geol. Soc. America Abstracts with Programs, v. 37, no. 4, p. 83-84.

Wood, C.A., and Kienle, J., 1990, Volcanoes of North America: The United States and Canada: Cambridge University Press, Washington, DC, USA, 354 pages.

This post is a submission for The Accretionary Wedge, being hosted this month by BrianR at Clastic Detritus: "speculate about the future of the Earth within the context of geological processes/events." This is Accretionary Wedge #15, despite the post title.

Accretionary Wedge #15: Pondering the geological future of Earth

And Even Another GeoBlog

Here's another geoblog, written by a self-described "geology person" - whose main interest, according to his profile, is rocks.

The blog is Outside The Interzone, by Lockwood. In one post, while speaking about Deep Time (geologic time), he says:

As a geology person, one learns, in a symbolic way at least, to contemplate the world from completely different time scales. Mostly longer and slower, but sometimes, as with volcanic explosions, meteorites and other fast, energetic events, you need to be able to consider the world on time scales shorter and faster than human experience can really register. It's a joy of the discipline, to look for consistency across scales of time and space, that most people never have the opportunity to perceive- to their great loss.

Check it out!

The Principle of Uniformitariansim

The principle of uniformitarianism is one of the earliest formed principles of geology. It is a principle, not a theory.

The principle of uniformitarianism is stated simply as "the processes affecting Earth today are the same ones that affected it in the past" - as quoted from What Stories do Rocks Tell, at ClassZone. Besides describing the principle of uniformitarianism, the website goes on to outline the other principals of geology:

• the principle of superposition
• the principle of original horizontality
• the principle of cross-cutting relationships

The principle of uniformitarianism is fundamental to understanding geology and working out what actually happened in the past, during the long history of the earth, during the eons of geologic time. This main principle is sometimes stated as "the present is the key to the past."

If geologists could not use what they see around them now, by studying geologic processes and relationships occurring and in place today, it would be difficult if not impossible to determine what had happened in the past. Any ideas, concepts, or hypotheses that a geologist might form about the past - anywhere or anywhen on earth - would be useless without the principle of uniformitarianism, simply because one could not go to the geologic record - which is also a record of events and processes that include the chemistry of the past, the physics of the past, the biology of the past, the hydrology of the past, the geochemistry of the past, the geophysics of the past, and the bio-geology of the past - and do any meaningful interpretation at all.

If, for example, sedimentary rock layers of the past were laid down sideways or vertical instead of in horizontal fashion as we see them being laid down today - say, because the gravity on earth worked very differently in the past - then any interpretation of what happened to older rock layers that are now folded, faulted, and otherwise deformed, would be incorrect. Another way of looking at this would be as described at MSN Encarta:

The principle of uniformitarianism depends on the 'uniformity of laws,' which assumes that the laws of physics and chemistry have remained constant. To test uniformity of laws, geologists can examine preserved one-billion-year-old ripples that look very much like ripples on the beach today. If gravity had changed, water and sand would have interacted differently in the past, and the ripple evidence would be different.

In other words, ripple marks today indicate that water has flowed or wind has blown¹ (because we also see ripple marks created in areas of blowing sand), and therefore ripple marks in rock formations of the past also indicate the same thing. By measuring and comparing ripple marks formed today under different circumstances of water or wind formation, different speeds of water current or air movement, and different environments, a geologist can then apply the data collected today to the ripple marks of the past and hypothesize an environment in which those ancient ripple marks formed.

Geologists at first sometimes took the principle of uniformitarianism to such an extreme that catastrophic events of certain kinds were almost completely ruled out, perhaps because the principle was partly formulated as a tenet opposite to the then prevailing doctrine of catastrophism. The two major types of events somewhat ruled out by geologists of the past were huge, giant floods and huge, giant volcanic eruptions. The reason for these things being ruled out or overlooked while using the principle of uniformitariansim, is that these things - huge catastrophic floods, and huge catastrophic volcanic eruptions - are not seen happening on earth today. The discovery and recognition by J. Harlan Bretz of the very large series of floods that formed the Channeled Scablands of Washington state, eventually was accepted as something that 1) really happened and 2) could happen again if circumstances similar to those that caused the floods occurred again. It's interesting to note that it was in part the identification of huge ripple marks that clinched the acceptance of the way-larger-than-usual floods. In a way, then, the principle of uniformitarianism helped confirm Harlan Bretz's ideas - if you look at the size of ripples in rivers today and compare them to the size of the ripples formed by these past floods in the Channeled Scablands, you would have to conclude that an immense volume of water was required to form them.

Likewise, the recognition of the very large volcanic calderas of Tertiary age in central Nevada and of Quaternary age in Yellowstone Park, Wyoming made geologists realize that large, "catastrophic" volcanic eruptions are part of the earth's history and therefore could happen today/soon, or sometime in the near to far future. The relative size of the eruptions at Yellowstone (Yellowstone Park and environs actually contains several - at least three - calderas) compared to that of many volcanic eruptions that we, as people, think of as large or "catastrophic" is discussed at Yellowstone Caldera. It can be good to remember that events that are considered catastrophic are on the large end of a continuum of smaller to larger events, and that the large events are often considered catastrophic only because of the effect they could have on humans. We are the ones defining normal earth processes as catastrophic.

Anyone attempting to do geology without using the principle of uniformitarianism as described above, is really not doing geology at all.

1. I am reminded of the movie Little Big Man, in which Pawnee chief, Old Lodge Skins, says "...as long as grass grow, and wind blow, and the sky is blue." One of my favorite quotes, for some reason.

UPDATE 23Jun2010: Also see Rapid Canyon Formation and Uniformitarianism at Clastic Detritus and Of Catastrophic Floods and Canyons at 4.5 Billion Years of Wonder.