Sunday, November 30, 2008

Geology is "Hot" because...

  1. I get to climb around on rocks and balance myself in precarious positions.

  2. I get to wear field boots,

  3. and field sandals (see above).

  4. I get to fly around in helicopters and stay out in the field all night when idiot pilots forget to pick me up.

  5. I get to have a breccia collection.

  6. I get to find v.g. (visible gold) out in the middle of nowhere (well, near Beatty, NV in this case).

  7. I get to stop at roadcuts and look at rocks, which I've been doing at least since I was 5 (my first memory of a roadcut was from age 5, a particular slaty cut in eastern Nevada).

  8. I get to have strange geology dreams.

  9. I get to write geology poems and geology songs.

  10. I get to find faults everywhere, and it's a good thing, not a bad thing.

  11. I get to travel, even on days off.

  12. I get to go mapping.

  13. I get to find geology everywhere I go, even on vacation.

  14. I get to work in the desert, with snakes and things.

  15. I get paid to drive and paid to eat.
I get to know that subduction really happens, and that it has been happening for a long, long time. And I get to know that one really neat woman, the geologist and geophysicist, Tanya Atwater, contributed greatly to ideas of plate tectonics when those ideas were still being formulated. Her work, along with geological work done in, on, around, and over active and erupting volcanoes, constitutes part of my current definition of "hot" geological science.

Menard, H. W., and Tanya Atwater, 1968, Changes in direction of sea floor spreading. Nature, v. 219, p. 463-467. Reprinted in Plate Tectonics and Geomagnetic Reversals, p. 412-419, W. H. Freeman Co. San Francisco, 1973.

Atwater, Tanya, 1970, Implications of plate tectonics for the Cenozoic tectonic evolution of western North America. Bull. Geol. Soc. Amer., v. 81, p. 3513-3536. Reprinted in Plate Tectonics and Geomagnetic Reversals, p. 583-609, W. H. Freeman Co., San Francisco, 1973. Reprinted in U.C.S.D., Scripps Inst. Oceanography., Contributions, Vol. 40, Part 2, p. 1249-1271, 1970.

This post is being submitted for the December Scientiae Carnival, which is being hosted by Isis the Scientist, who loves Naughty Monkeys and Star Trek.


Bowman Creek: A Tribute

bench by creek

Old bench at Bowman Creek.

And now, I'll finally get around to why I drove up that old road to Bowman Creek, why I hung around there for a couple hours.

I looked for our old camp at Bowman Creek a while before I actually found it. When I had been back there with geo-colleague BS in the late 1980's (maybe 1988), I had been able to find the site by driving right to it. This time, everything seemed overgrown: the bushes higher, denser, and harder to walk through, the creek overgrown with trees and wild rose.

The actual campsite, out on the fan away from the creek, is fairly easy to find. I was looking, however, for a particular spot on the creek, the spot where Bob Shannon - our intrepid expediter, camp builder, and drilling arranger - had built a bench under the shade of some creekside trees. In fact, he had built every single one of our many camp structures through the summer - here and there across Nevada - inlcuding various forms of camp shade.


The bench that Bob built.

I had remembered a bench made of nice wood built into the side of a tree with a large trunk, sturdy, fully in the shade, right next to the creek. What I found instead, was an old, gray, and sun-weathered bench made mostly of 2x4's and other dimensional lumber, a bit rickety looking but still sturdy, with some of the boards missing. It looked like it had not been built into or right against a large tree, but instead had been built on the ground, and was now near a swarming mess of water birch tree trunks, all smaller than the trees I remembered. The original tree, however, may have been cut down, leaving the bench resting on the ground, possibly upside down; the only clue being one leg of the bench, on the right in the above photos, which is made of non-dimensional wood, perhaps part of a tree. I found old aspen or cottonwood trunks lying around here and there, trunks about twice the size of most current creekside trees.

So, I don't know. I have a clear memory, and I have the above pictures that don't quite match.


View from the bench.

I walked over and sat on the bench, sure that I was not the first person who had used it since our 1970's camp, sure that it was the same bench I re-visited in the late 1980's. I sat there listening to the rushing creek waters, and thought of Bob. The first time I came back, BS collected grasshoppers for fishing bait in the tall grass on the far side of the creek (there are trout in the creek), while I sat and reminisced.

It was close to midday. In the afternoon - a time corresponding to our back-then arrival in camp after a day of geologizing across the valley - the bench would still be in the shade. Shade was important when we first arrived in camp in early September; later, shade was unecessary.


Fall leaves overhead.

I sat on the bench, remembering. The leaves overhead had not yet fallen, though they looked ready.

Bob died sometime in the 1980's from a brain tumor, sometime back before my last visit to the creek with BS. Bob was old when I first met him—his sun-browned and craggy face matched the mountains and deserts in which he lived and worked. He was rugged, even austere, yet warmhearted and good-natured. At the Bowman Creek camp we showered with hot water in wooden, closed-in shower stalls that Bob built; we sat in the deep, brown-and-emerald-green shade next to the rushing, ice-cold creek on the bench that Bob built. We kept our beer in a wide spot in the creek, just below that bench.


A place to put the beer.

From the bench, I looked over toward the creek, toward the pool in which we chilled our beer.

Bob Shannon is gone now. He was the first and oldest of our collective group to die. He and his wife, who he always called “She,” had purchased a modest dream cabin along the western bluffs overlooking Walker Lake, just a few miles north of Hawthorne, NV. Now he lives on in me, and in another female geologist he encouraged in his warm and slowly sagacious way, and he lives on at Bowman Creek, where one piece of his multitude of handcrafted camp contraptions remains. We tore down the rest of his constructions each time we moved camp, dismantling outhouses, showers, shade awnings for trailers and tents, and all else into their component parts of 2x4’s, 4x4's, and plywood: pieces to be hauled by 4WD to our next campsite.


Looking up the fan toward the base of the Toiyabe Range.

There being no beer to be had, I walked back up to my truck and moseyed on.

Saturday, November 29, 2008

Bowman Creek: The Camp


Photo of the creek crossing.

We camped at Bowman Creek during September and October, although the camp had been there through much of the last part of the summer before I actually arrived. I had been part of a second camp group before that, and when several students left both camp groups to go back to school at the end of summer, those of us who remained joined forces at Bowman Creek.

Instead of bringing the trailer up the road I described earlier, the first crew had driven the trailer in on the other road and had then driven it down the alluvial fan until they finally found a creek crossing

Photo of the place I had my tent.

Camp was a large affair, at least by summer's end, with a camp trailer, several 8x10-foot canvas tents, a large mess tent, and then, when the claim stakers came, a large Quonset-hut-like building, which replaced the smaller mess tent. We had hot showers at Bowman Creek camp, with creek water piped into camp through black plastic piping. It came down the alluvial fan from a higher elevation, so the water had good hydraulic head. At camp, it was then piped into 55-gallon drums on top of one or two wood-frame shower stalls. It was usual for the water to be heated during the day by solar heat, but with September turning chilly and clouds moving in for days at a time, the water was finally heated with propane. It's one thing to take a creek-cold shower at the end of a hot day (icy, brrrr!); it's not any good at all to do that at the end of a chilly day, a chilly day that is rapidly getting colder because the sun has already gone behind the shadow of the Toiyabe Range.view

A view across Big Smoky Valley of the Toquima Range.

We had great views across the valley from all places in camp. The photo above shows what the view from my tent door would have looked like. We had similar, though more expansive views from our outhouse located somewhere higher on the alluvial fan. It was a wooden structure, and it was open to the east for the view, built without a door. We had a system of leaving a red flag visible, so you could tell from a distance whether the outhouse was already in use.view

A view across the valley looking toward the center of the Northumberland caldera, with dust from a vehicle marking the Northumberland dirt road.

The view from the Quonset-hut area was nice, too; we could see the entire Northumberland caldera, and could also see down the valley toward Mt. Jefferson and Round Mountain. Round Mountain was mostly just an old town, then, but the current operation at the Round Mountain gold mine had already begun, though it was initially much smaller.

Friday, November 28, 2008

Friday Fault Photos #9

On a fairly recent road trip to Baker, NV (gee, I almost wrote Baker, CA - yikes! - so many *fond* memories from there), I took the opportunity to look around while MOH was getting gas, and discovered that you can see the Snake Range decollement or detachment fault from town.
In case you need to have the low-angle fault pointed out, here's a great photo with a power line running parallel to the fault! Upper plate rocks are dipping westward (to the left), and lower plate rocks, besides the white-line mylonite right along the fault, are obscure.
Ah, then we drove up Wheeler Peak, where the road is closed part way up the mountain to the upper campground, and we had this great view of part of the Snake Range detachment fault, with a snow-covered mountain in the background. The detachment fault is a little difficult to see, but is essentially following a somewhat curved or arched line where all the tilted upper plate rocks end. The snow-covered mountain might be Mount Moriah, one of the highest peaks in Nevada.
And here's the Snake Range detachment fault again, this time from the rock glacier on Wheeler Peak. Bristelcone pines grow on the rock glacier, and can be seen in this photo mostly toward the far edge of the glacier. More info can be found about the detachment fault, the geology of the area, and the bristlecones in my series on Wheeler Peak.

Way out west, they got a name
For rain and wind and fire
The rain is Tess, the fire's Joe and
They call the wind Mariah [Moriah, in this case.]

See these sites for lyrical references.

Thursday, November 27, 2008

First Thanksgiving

The first Thanksgiving I had in Nevada was spent while on a required field trip during my first semester as a grad student, a long time ago. The field trip was the third in a series of three, and although a lot of the married students really complained about their family obligations, there weren't many of them, and our old professor was quite set in his ways.

So, off we went, to southern Nevada, spending the entire Thanksgiving break on a geology field trip. There were several highlights of the trip, one of which is a famous outcrop in Death Valley, which MJC Rocks at Geotripper posted about some time ago, and another of which was a poker game inside tents near Lake Mead.

What I remember best, though, was eating Thanksgiving dinner at the only place open in Beatty on Thanksgiving Day, the old Exchange Club, which may not be open anymore. The Exchange Club sits at the main intersection or corner in Beatty, where Highway 95 makes a turn to the east if you are headed south toward Vegas from Tonopah or Goldfield.

That dinner was my first Thanksgiving dinner in Nevada, and my first Thanksgiving dinner in a casino (fortunately there haven't been too many of those). The dinner was okay, but that's the only time I've ever eaten in a restaurant where a "C" rating from the health department was so prominently displayed.

The second most memorable thing about Thanksgiving in Beatty: we stayed that night in the Beatty dump, sleeping on the ground. Now, this wasn't the infamous Beatty Dump - though many jokes have been made - just the local landfill.

Here's hoping that your Thanksgiving dinner will be a bit more inspiring than that first one, and that you will have a better place to sleep.

Not the Beatty dump - it's just any old mine dump in Nevada.

Wednesday, November 26, 2008

Have Truck Can Travel

My truck is all fixed, and now I can travel with great security instead of wondering every time I pull off the road whether I'll be getting back on or not. YAY!

Travel over the weekend, travel to upcoming meeting, travel for Christmas, travel...

Tuesday, November 25, 2008

Boots #1: Just Standin' Around

Well, I didn't have that much to write about (actually I have tons of things to write about, and tons of things to do), so I thought I'd just post a few pictures of geo-types standing around out in the field in their favorite footwear (oh, maybe that should be a friday footwear foto thingy). Mostly these are field boots or hiking boots, but some are tennies or lightweight hiking boots. As you can see, the geos are all standing on outcrops, which is one place geo-types like to be. The outcrops, all in Nevada of all places, are of 1) silicified rock, 2) unknown rock, 3) oxidized rock, 4) white tuff.

Monday, November 24, 2008

Here and There

I've been going here and there, and now have to get on with making lists, sending emails, and getting things done - like, can someone fix an intermittent vehicle problem? - so will just post a couple quick pics from the last road trip. The first, near Middlegate; the second, somewhere out near Eureka.

Friday, November 21, 2008

Friday Fault Photos #8

While out climbing around in the hills the other day, with MOH on one of our hikes, I came upon a fault zone in quartzite, along with a lot of steep and precarious ledges. There I am, above, standing on one ledge, looking down to another ledge in the shadows below the pine tree on the left, and looking even farther down to the ground below. Why am I doing that?
I'm doing that because from the ledge below the pine tree, and all the way to the ground, the entire mini-cliff of quartzite is slickensided. In the photo above, I've reached the lower ledge, and am trying to get a foothold so I can take a photo (surprise!). You can see some of the slickensides just above that field boot of mine.
Ah! Here I've finally reached the point I want, and am standing on the ledge, looking down at a golden brown, iron-stained, slickensided surface, with my boots pointing more or less parallel to the slickenlines (straight down). It's a funny perspective, and MOH tells me that when I climbed down the ledge to the ground, that the slickensided mini-cliff was over my head, which means it was at least 5 feet high, maybe higher.

Thursday, November 20, 2008

I'm a Doer?

What am I doing?

This little personality quiz, based on the writing on one's blog or website, was pointed out recently by Suvrat at Reporting on a Revolution. The website analyzer can be found here. The analysis is based on the Meyers-Briggs Type Indicator test or the Keirsey Sorter. I'm supposed to come out INFP, but my blog comes out ESTP. (Actually, since the first time I took the assessment in the early 1990's, I have come out all over the place, apparently depending on my mood or something like that.)

ESTP: the active and playful type. They are especially attuned to people and things around them and often full of energy, talking, joking and engaging in physical out-door activities. The Doers are happiest with action-filled work which craves their full attention and focus. They might be very impulsive and more keen on starting something new than following it through. They might have a problem with sitting still or remaining inactive for any period of time.
As I write this, I'm not feeling particularly active or playful, and am not full of energy. I probably am overly attuned to people, although that doesn't always help me do or say the right thing. I do occasionally work outdoors (surprise, I'm a geologist!). I almost always spell occasionally wrong, but that apparently isn't part of the test. I don't know if the test would give different results for different posts, or if it's just set up for a whole website. I will warn you that they save your site and results, although I can't really think why, unless they really think their analysis means something.

Breccia - A Popular Rock

Well, at least it's popular with me, and has been mentioned recently by a couple other geobloggers. As Andrew describes, breccias can form in many different ways - and he shows a picture of a breccia in an unknown rock (see comments) formed by unknown causes. Callan Bentley shows a breccia in limestone (his second photo), and he wonders if it might be a collapse breccia.

The breccias I photograph are often associated with faults, like this one, but it often is hard to tell what caused a breccia to form while out in the field. The breccias shown below were all found as loose rocks on a steep slope, a slope covered with lots and lots of breccia, probably not all formed the same way.
This breccia, which is the brownish portion to the left in the above rock, is a heterolithic breccia (more than one type of rock fragment) composed of white to gray, matrix-supported (the fragments don't touch each other), subangular to angular fragments in a brown siliceous matrix. The brown coloring is from iron oxides. The white to light brown portion of the rock on the right is dolomite, and it may be a large fragment in the breccia - but that is impossible to tell from this small rock - one would have to see the outcrop. I would suspect that this is either a fault breccia or a hydrothermal breccia, but would really want to see the outcrop before saying for sure.
The breccia above is monolithic breccia (one type of rock fragment) composed of mostly matrix-supported, subrounded to (maybe) subangular fragments of light gray dolomite in what appears to be a matrix of ground-up dolomite, or rock flour, suggesting that this is a fault breccia.
The above gray breccia is heterolithic, composed of mostly subrounded fragments of white to light gray quartzite and dark gray to black dolomite and limestone. I'm not sure if the funny-looking, almost white (cream-colored) fragment in the upper right of the rock is actually part of the breccia, or was something plastered on loosely. I didn't have all my geology tools with me (like my pocket knife). The gray breccia matrix is composed of smaller breccia fragments, angular to subrounded, in the gray carbonate matrix (limesone or dolomite). It's unclear to me what kind of breccia this is. It is strongly fractured by closely spaced fracture sets that are almost turning the rock breccia into a type of breccia sometimes called a crackle or crackled breccia. These close-spaced fracture sets can be seen better in the next photo of the same rock, below:

Here, above, is another breccia, with a field boot on top of it! This rock is almost not a breccia, being mostly a fractured rock to a crackle breccia. The fragments are sometimes not separated from the adjoining rock by more than a fracture, and the fragments haven't rotated or moved much from their original position, except, perhaps, in the lower right part of the rock. The dark gray to black fragments are clast-supported (touch each other), are subangular to subrounded, and are composed of dolomite or limestone.

In the lower left of the above photo, the black, fractured to brecciated rock is resting on a rock slab or outcrop of gray breccia. (Trust me, breccia is everywhere on this particular slope!)
The above rock, and the next, speak a little to the question of what were the rock holes seen in a previous post of mine. The light brown veinlets of silica and iron oxide stand out with respect to the somewhat weathered out black marble and marble fragments. These irregularly shaped to rounded-looking fragments may or may not have been rotated as in most breccias.
The above breccia is composed of subangular to rounded gray marble fragments, partly weathered out from the brown, iron-oxide-rich silica matrix and silica veinlets. At first, I thought the light brownish gray fragments, which are particularly shiny in the sun, were composed of pyrite or marcasite, but no, they are marble. There are a few square holes completely weathered out in the silica matrix where cubic pyrite crystals used to live. This breccia could be a tectonic or hydrothermal breccia, or some combination thereof - but, again, an outcrop rather than a loose rock on a scrabbly slope would be more helpful in determining the origin of the breccia, and so would a little microscope work.

More on fault breccias here - although the link goes only to an abstract, it does have some breccia definitions.

Tuesday, November 18, 2008

Five Things Meme

I'm taking this one from Cath @ VWXYNot?, who tagged "anyone whose breakfast included / will inlcude cheese." [The breakfast was scrambled eggs with cheese.]

5 things I was doing 10 years ago:
(Let's see, 10 years ago was 1998.)

  1. Watching one of my nieces take her first steps.
  2. Packing an over-full U-Haul.
  3. Driving down the Alcan.
  4. Finding a new place to rent.
  5. Looking for work.

5 things on my to-do list today:
(Checks calendar - oh, today's a day off.)
  1. Sleep late. ✓
  2. Have coffee.✓
  3. Mail bills.✓
  4. Do some laundry.
  5. Go for a hike.✓

5 snacks I love:
  1. Ice cream, almost any ice cream.
  2. Coffee with cocoa / coffee without cocoa / cocoa without coffee
  3. A Blizzard (especially when in Alaska).
  4. Peppermint patties.
  5. Reesie cups (okay, so I spelled it wrong).

5 things I would do if I was a millionaire:
  1. Drive the Alcan again, taking my time for once.
  2. Buy a new field vehicle, one that gets good mileage.
  3. Build a new house in the back yard.
  4. Use solar panels.
  5. Work less; donate more.

5 places I've lived:
  1. Nevada.
  2. Alaska.
  3. The East Coast.
  4. North of the Arctic Circle.
  5. In the field.

5 jobs I've had
  1. Receptionist [yuck].
  2. Teach Op Min and Petrology.
  3. Geologist.
  4. Artist.
  5. Consultant.

5 rocks I love:
(For geologists or any others who also want to add rocks.)
  1. Breccia, any kind.
  2. Ash-flow tuff (did I mention breccia?)
  3. Veins (and brecciated veins)
  4. Rocks with secondary K-spar veinlets (I don't like these to be brecciated, but the veinlets can cut breccias).
  5. Jasperoid (also to hate, if sampling), brecciated or not.

5 categories of people I'll tag:
  1. Any geologist.
  2. Anyone who has driven the Alcan, in either direction.
  3. Anyone who has lived north of the Arctic Circle.
  4. Anyone who hates moving.
  5. Anyone who considers themselves an artist.

One Year Ago Today: Fall at the Lake

By this time last year, fall at the lake had progressed to no leaves being left on our deciduous trees - well, maybe there's one.
Instead, they were all on the ground, mostly still yellow to golden brown, but some turned an interesting sooty brown to sooty gray color.
Unlike this year, we had a few small flowers left in the garden. These flowers aren't exactly wildflowers - we planted them - I think they are supposed to attract butterflies. They are so tiny!

The dried flowers below came with the house: gaillardia. They are at least semi-wild and spread easily. This time last year, there were still a couple small blooms! Not this year, though.
This year, I won't see these kinds of images, because I won't be making it to the lake probably until December, or even January. My end-of-year schedule seems a little strange - MOH was at the lake when I was working, and I will be in Reno when he is working. We managed to overlap our days off a little bit, by three or four days, and we will manage to have two to three days off together over Thanksgiving.

Monday, November 17, 2008

A Few More Field Days

OR: Just Another Day in Paradise
Shortly after the photogenic frost came, in fact, the very next day, rain came and made everything wet and muddy. Snow fell on the high and not-so-high mountains.
The resulting snow made the hills a bit inaccessible for field work for a few days... until the sun finally stayed out long enough to melt all but the highest snow.
More recently the days have looked like this: yellow-green juniper trees with a background of bluish green piñon trees. The afternoon shadows come early, and the low light seems to make everything brighter and more colorful.
Look closely: a couple juniper berries!
And then the sun goes down, slowly, creating even longer shadows, until nothing but shadow is left.

Sunday, November 16, 2008

More on Endings

As Kim noted about a week ago, there have been some hints and threats of an ending field season going around, here and there in the west.
My first clue that the field season was ending, besides seeds falling everywhere, was some bright shiny frost I saw while driving to work one morning. I'm not sure it was the first frost, you understand, but it was a definitely photogenic frost.
Photogenic frost - on grass 'neath juniper tree - light and shade combined.
Later in the day, clouds moved in, making it difficult to tell one gray rock from another. A weak sun column (or sun pillar) formed in the west in the gray sky.

Friday, November 14, 2008

Friday Field Photo

Wandering around out in the hills a while ago, I came upon some old mine dumps. (I was in Nevada, after all.) The actual sources for the lower, larger dumps seen in the above photo are, as far as I could tell, up the hill: two smaller dumps you can barely see above and between the lower two dumps (click to enlarge). That is to say, the lower dumps are composed of waste material moved downhill from the upper workings by the oldtimer miners. Usually, that kind of transportation is done underground, but if any lower haulage adits (tunnels) exist near these lower dumps to connect to the upper workings, they weren't obvious, or were long-since caved in.

On one of the lower dumps, I found this interesting and colorful rock, an iron-oxide-rich rock with colors of brown, reddish brown, and yellow brown.

The rock has some large relict pyrite cubes in the upper left, and below that and cutting through the rock are some irregular veinlets of silica, which mark spaces where former rock fragments and former sulfides have been leached and weathered out, leaving holes and soft, punky, yellow and brown Fe-oxides. The host rocks to this oxide material is - limestone!

P.S. Any ideas about the diamond-shaped hole in the upper left below the relict pyrite cubes?

Wednesday, November 12, 2008

A Geological Haiku

Mahogany seeds
Over cherty limestone lie
A field season ends

This haiku is in response to a haiku meme started here.
The seeds are from the mountain mahogany tree, which is not a true mahogany.