Naked Science Forum

Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: JimBob on 12/11/2007 01:42:14

Title: Geology In Pictures
Post by: JimBob on 12/11/2007 01:42:14
Thin sections are very thin slices of rock in which most minerals are translucent. Minerals are said to be anisotropic - having physical properties that are different in physical propeties along different crystal axes.

To make use of the different amount of retardation and identify minerals polarized light is used to produce different optical effects that help identify the mineral being examined.

Using two polarizing filters, one above the microscope stage and one below the stage, allows separation and possible retardation of one of the perpendicular light wave components.


from http://www.uwgb.edu/dutchs/petrolgy/olivine.htm
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi38.photobucket.com%2Falbums%2Fe111%2Fgeezer69%2Fpolarisedlight.gif&hash=741e625b6f010393824211b46e6a4135)

As the two beams of polarized light pass through a crystal in thin section which IS seen in 3D, not 2D, they travel at different speeds and get out of phase because of anisotropy. The slow ray is said to be retarded and the phase difference is called retardation.

If the retardation is a whole number of wavelengths (upper right), the beams recombine with the same orientation as when they entered the crystal. These wavelengths will be blocked by the upper polarizer.

If the retardation is a whole number of wavelengths plus one-half (upper left), the beams recombine with an orientation perpendicular to the original direction of polarization. These wavelengths will be fully transmitted by the upper polarizer.

It is being out of phase at other any other combination other than 1/2 or 1 wavelength that produces colors of different wave length.

This may be Greek to most of you but the pictures of these properties in different rocks can be stunningly beautiful.

Olivine (a rock made up of all one mineral, olivine see http://en.wikipedia.org/wiki/Olivine) There are two microscopic thin sections below.

from http://www.uwgb.edu/dutchs/petrolgy/olivine.htm

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi38.photobucket.com%2Falbums%2Fe111%2Fgeezer69%2FOLIVINP1.jpg&hash=6ba371ec2756aa49ae0bfc5cd4cd01f5) One polarizer.


Same rock under cross-polarized light.

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi38.photobucket.com%2Falbums%2Fe111%2Fgeezer69%2FOLIVINX1.jpg&hash=999eca1edb77580b204e1df0b596c396)


For more beauty from rocks and the minerals that make them up see:

 http://www.microscopy-uk.org.uk/mag/artfeb04/iwouslides2.html
Title: Re: Geology In Pictures
Post by: neilep on 12/11/2007 02:00:43
A LAYERED SEDIMENTARY ROCK.


* 802642.JPG (36.15 kB . 362x428 - viewed 11749 times)


Jim can tell ewe all about it.................he was there when the layers were laid down !! [;)]



Title: Re: Geology In Pictures
Post by: JimBob on 12/11/2007 15:58:21
This is a layered sedimentary rock under artificial light. IT DID NOT come out of the ground that way. Why I remember when it was just a few piles of a few sand grains.... the rain came and there were suddenly other sand grains dancing around my piles ........ Pardon me, I need the loo
Title: Re: Geology In Pictures
Post by: neilep on 12/11/2007 17:35:15
A Beautiful Geode-Amethyst


* geodo-amethist_001-600.jpg (42.08 kB . 600x600 - viewed 16729 times)
Title: Re: Geology In Pictures
Post by: Bass on 12/11/2007 18:22:00
Let me guess Neil- you found that in your garden?
Title: Re: Geology In Pictures
Post by: neilep on 12/11/2007 18:42:27
Let me guess Neil- you found that in your garden?

LOL !!..Not that one...

..but my son has these..which he found in our window box !! [;)](they're guarded by Darth Vader)


* aaaaairocksndex.php.jpg (13.92 kB . 174x242 - viewed 11199 times)


* Iaaaaaamage2.jpg (43.35 kB . 574x251 - viewed 11263 times)
Title: Re: Geology In Pictures
Post by: Alandriel on 12/11/2007 21:38:26
Quote from: JimBob
....This may be Greek to most of you but the pictures of these properties in different rocks can be stunningly beautiful.
(from first post)

Much of it all is (and probably somewhat will remain forever...) Greek to me but it's great to have this thread with info and pics for dummies like me. Thanks for starting it - fab idea!!
 [;D]


talking of olivine.........one of my favorites 'rocks'
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.iun.edu%2F%7Egeos%2FZoran%2520IUN%2FG%2520101%2FPhotos%2FOlivine1.JPG&hash=8df316048215ea5b284e244697c1208a)
Olivine - some call it also Peridot? or maybe I'm just confuzzeld as ever
I don't mind the bigger green cousin EMERALD either - gotta love green rocks!
 [;D]
Title: Geology In Pictures
Post by: JimBob on 13/11/2007 00:34:04
Hi Alandriel,

Thanks for the purty picture. Yep, also known as peridote when it occurs in gem quality crystals, like the one you posted.

Olivine is a magnesium iron silicate with the formula (Mg,Fe)2SiO4 that can range in composition from all Magnesium to all Iron.  A mineral whose composition can vary is a solid solution instead of a compound as the same space in the crystal lattice can accommodate (but not simultaneously) two or more atoms of different but equivalent substances. It includes both forsterite (Magnesium endmember) and fayalite (iron endmember). Peridote is a mineral close in composition to the magnesium endmember forsterite.

Olivine is one of the most common rock-forming minerals in the earths crust.
Title: Geology In Pictures
Post by: Bass on 13/11/2007 21:18:40
Uplift(2001) centered around the Norris thermal basin, north of the Yellowstone Caldera, as shown by radar interferometry.  This area has since subsided, suggesting it was due to hot water.  Image from Yellowstone Volcanic Observatory.


* 96_00norrissm.gif (81.63 kB . 350x295 - viewed 14534 times)
Title: Geology In Pictures
Post by: Alandriel on 13/11/2007 21:32:12

I looked up radar interferometry but that did not tell me too much about what the meaning of your picture is Bass.

What do the different colour bands and 'blotches' mean / represent?
Title: Geology In Pictures
Post by: Karen W. on 13/11/2007 21:39:33
Quote from: JimBob
....This may be Greek to most of you but the pictures of these properties in different rocks can be stunningly beautiful.
(from first post)

Much of it all is (and probably somewhat will remain forever...) Greek to me but it's great to have this thread with info and pics for dummies like me. Thanks for starting it - fab idea!!
 [;D]


talking of olivine.........one of my favorites 'rocks'
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.iun.edu%2F%7Egeos%2FZoran%2520IUN%2FG%2520101%2FPhotos%2FOlivine1.JPG&hash=8df316048215ea5b284e244697c1208a)
Olivine - some call it also Peridot? or maybe I'm just confuzzeld as ever
I don't mind the bigger green cousin EMERALD either - gotta love green rocks!
 [;D]

MY birthstone and my favorite color... I have never seen one in the raw like that! Very nice.....Beautiful!
Title: Geology In Pictures
Post by: Bass on 13/11/2007 23:48:57

I looked up radar interferometry but that did not tell me too much about what the meaning of your picture is Bass.

What do the different colour bands and 'blotches' mean / represent?

By taking two different passes using satellite radar (INSAR), usually sepatated by a year or two, you can create an intereference pattern if the height of the ground has changed. 
"InSAR provides infrequent (annual to semi-annual) but highly detailed images of the amount of movement of the ground relative to a satellite. The technique is very useful for monitoring ground movements or ground deformation at volcanoes because detailed data can be collected for a relatively large area from space. By aiming a pulse of radar energy at the ground and then recording information about the return signal, such as the time traveled by the radar waves, InSAR quickly provides data for an entire area. By returning to the same area at different times, we can gain information about relative ground movements over time. The InSAR data are processed into images, called interferograms."http://www.thenakedscientists.com/forum/index.php?topic=11364.msg139151;boardseen#quickreply (http://www.thenakedscientists.com/forum/index.php?topic=11364.msg139151;boardseen#quickreply)

In other words, an interference pattern is created, and the color bands represent discrete changes in elevation.  For this case, the center of the pattern was uplifted about 125mm (or 5in for the metrically impaired on this side of the pond).  This has proven useful for volcanoes and earthquake prone locales to measure surface deformation over a large area.  Think drops of oil on water- the thickness of the oil creates interference patterns.
Title: Geology In Pictures
Post by: neilep on 14/11/2007 01:30:02
The Giant's Causeway (or Irish: Clochán na bhFómharach[2]) is an area of about 40,000 interlocking basalt columns resulting from a volcanic eruption. It is located on the North East coast of Northern Ireland, about 3 kilometres (2 miles) north of the town of Bushmills. It was declared a World Heritage Site by UNESCO in 1986, and a National Nature Reserve in 1987 (by the Department of the Environment for Northern Ireland). In a 2005 poll of Radio Times readers, the Giant's Causeway was named as the fourth greatest natural wonder in the United Kingdom. The Giant's Causeway is owned and managed by the National Trust. The tops of the columns form stepping stones that lead from the cliff foot and disappear under the sea. Most of the columns are hexagonal, however there are some with four, five, seven and eight sides. The tallest are about 12 metres (36 ft) high, and the solidified lava in the cliffs is 28 metres thick in places.


* Giants Causeway,06.jpg (72.97 kB . 460x449 - viewed 11707 times)


* Giants Causeway 1.JPG (43.71 kB . 370x246 - viewed 11536 times)

Title: Geology In Pictures
Post by: Alandriel on 16/11/2007 16:39:31
Quote from: Bass
In other words, an interference pattern is created, and the color bands represent discrete changes in elevation.  For this case, the center of the pattern was uplifted about 125mm (or 5in for the metrically impaired on this side of the pond).

So, in other words, the yellowish-orange centre of the photo marks an area that's been uplifted by 12.5cm (just to confuse the metrically impaired  [;)]) What about the other circles, e.g. blue etc.
Do the colours represent 'staggered raises' at regular invervals (more or less of course) from the outside to the inside with the innermost circle 'peaking' at 12.5cm ?



The Giant's causeway ***sigh***** been wanting to go see that for ages. Maybe next summer!
Title: Geology In Pictures
Post by: Bass on 19/11/2007 22:26:10
Alandriel- exactly right.  who says geophysics isn't your cup of tea?
Title: Geology In Pictures
Post by: JimBob on 20/11/2007 01:15:53
err Bass - that is remote sensing, not geophysics, Isn't it? Thought I'd just keep you honest, not a jackenape like me.
Title: Geology In Pictures
Post by: Alandriel on 21/11/2007 17:40:53
You guys crack me up  (https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fbestsmileys.com%2Flol%2F16.gif&hash=c1dc69d9ae62875e79ea5868a8cfa84b)

Geophysics sounds soooo much more posh(*) and glamorous than remote sensing.

Bass was simply being charming  [;D]


Besides - the guys on TV (timeteam I get coerced into watching) use geophysics but it looks like remote sensing LOL.
What's the difference?



(*)portside out starboard home  [;D]
Title: Geology In Pictures
Post by: Sarah Elizabeth on 17/12/2007 15:36:26
you might like to know that olivine, or peridot comes from the word peridotite as it coes from mantle peridotite and is formed under very high pressure conditions.
Title: Geology In Pictures
Post by: Bass on 09/05/2008 01:15:18
It's a well known fact that cattle align themselves towards large ore deposits.  These "bovinity rays" are more noticeable during the morning and evening hours.

Well developed bovinity rays near a Nevada gold mine:

 
* cattle2.jpg (40.18 kB . 288x216 - viewed 10667 times)

Moderate bovinity rays:


* cattle3.jpg (60.89 kB . 288x216 - viewed 10708 times)

Obviously no ore nearby:


* cattle1.JPG (56.72 kB . 288x189 - viewed 10633 times)
Title: Geology In Pictures
Post by: JimBob on 09/05/2008 01:50:05
Now this seems like a load of bull to me - get it? BULL?

Oh well, forget I said anything.
Title: Geology In Pictures
Post by: Bass on 09/05/2008 03:13:47
Now this seems like a load of bull to me - get it? BULL?

So sayeth the expert in BULL!
Title: Geology In Pictures
Post by: JimBob on 09/05/2008 05:09:57
I am all hat and all cattle

TEXAS FOREVER!
Title: Geology In Pictures
Post by: Evie on 07/10/2008 19:30:25
What do you call cattle with a sense of humor?
















Laughing-Stock  [;)] [;)] [;)]
Title: Geology In Pictures
Post by: Bass on 19/03/2009 19:23:18
New underwater volcanic eruption near Tonga


* tonga_amo_2009077.jpg (66.03 kB . 720x480 - viewed 9698 times)


http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=37572&src=nha
Title: Geology In Pictures
Post by: JimBob on 30/03/2009 02:54:52
Note the fold at the top of the mountain.

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi38.photobucket.com%2Falbums%2Fe111%2Fgeezer69%2FFoldedstrataCarboniferousandPermian.jpg&hash=5bb63190bbf4b3011da36e32a0301fa6)

CREDIT:

http://www3.hi.is/~oi/svalbard_geology.htm

Folded strata Carboniferous and Permian strata in Ingeborgfjellet, Van Mienfjorden, Spitsbergen

Photo: Ólafur Ingólfsson 2004
Title: Geology In Pictures
Post by: Solius on 04/05/2009 19:25:55

* DSCN1586.JPG (41.11 kB . 378x347 - viewed 3132 times)

Hi all! New to the forum. Here is a nice scolecodont that I collected last year. What is preserved is the mouth parts of an annelid worm. It is from the Ordovician of Kentucky.
Title: Geology In Pictures
Post by: Bass on 04/05/2009 19:32:07
Great photo!

Welcome to the forum.
Title: Geology In Pictures
Post by: JimBob on 04/05/2009 23:28:18
Yes - WELCOME !!!!!!!!!!!!!!!!

(Beware of the hungry Telost!)
Title: Geology In Pictures
Post by: Solius on 05/05/2009 05:25:15
Hey guys, thanks for the welcome.

(Beware of the hungry Telost!)

Probably, during the Ord it was the agnathids, and nautilids, that were of primary concern for the annelids. Though, around here, agnathids are unknown.
Title: Geology In Pictures
Post by: JimBob on 05/05/2009 23:26:41
Dang my typing - teleost

(i.e., the fish among us)
Title: Geology In Pictures
Post by: Bass on 06/05/2009 02:35:25
Yes - WELCOME !!!!!!!!!!!!!!!!

(Beware of the hungry Telost!)

 [?]??? [?]
___________________________________________________________________________________

HEY...I resemble that remark
Title: Geology In Pictures
Post by: JimBob on 06/05/2009 03:06:51
Yes - WELCOME !!!!!!!!!!!!!!!!

(Beware of the hungry Telost!)

 [?]??? [?]
___________________________________________________________________________________

HEY...I resemble that remark

Yes, you have that lean and hungry look, Cassius Micropterus sp..
Title: Geology In Pictures
Post by: G-man on 19/09/2009 07:22:00
This is for Jimbob, and anyone else.

Dear fallow Texan;

  Hi there Jimbob. I would be very happy if you would go new theories and look at Freemason’s science.
Even though it is not a new theory, but a study of the freemason’s work on the US dollar bill. It is a copy of what was on the old  Temples of Seth, Enoch, Solomon, and Hercules six thousand years ago. And it shows the makeup of the Earth, well before there was any Witten word.

G-man;

Title: Geology In Pictures
Post by: LeeE on 07/04/2010 13:17:03
Just saw this nice photograph of Halema`uma`u's plume rising straight up in the absence of low altitude winds (the moon is visible as a little bright speck just above the small dark cloud, to the right of the plume).

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fhvo.wr.usgs.gov%2Farchive%2Fspotlight_images%2F20081114_0041_L.jpg&hash=afdb41ca792a71c2b625679d9f78d21a)

(Photograph by M. Poland November 13, 2008)

The photograph is one of the featured pictures on the USGS HVO website at:

http://hvo.wr.usgs.gov/ (http://hvo.wr.usgs.gov/)
Title: Geology In Pictures
Post by: JimBob on 08/04/2010 15:51:36
I also like the lava flowing into the sea picture on that page
Title: Geology In Pictures
Post by: Bass on 05/05/2010 20:07:56
Eyjafjallajokull eruption captured May 4, 2010
NASA Earth Observatory
http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=43883&src=nha


* eyjafjallajokull_ali_2010122.jpg (102.21 kB . 720x480 - viewed 5400 times)
Title: Geology In Pictures
Post by: RD on 05/05/2010 21:43:08
Photo of Eyjafjallajökull 17th May (with lightning) ... http://apod.nasa.gov/apod/ap100419.html
Title: Geology In Pictures
Post by: Bass on 05/05/2010 22:28:05
Photo of Eyjafjallajökull 17th May (with lightning) ... http://apod.nasa.gov/apod/ap100419.html

Where did you find a time machine? [;D]

Cool photo!
Title: Geology In Pictures
Post by: RD on 05/05/2010 23:00:44
Oops 17th April  [:I]
Title: Geology In Pictures
Post by: RD on 19/05/2010 05:41:30
Where did you find a time machine? [;D]

Can fast-forward Eyjafjallajökull in time ...
@ 0:49
Title: Geology In Pictures
Post by: djdave on 21/05/2010 11:11:39
What a Nice Sight.
Title: Geology In Pictures
Post by: CreativeEnergy on 15/08/2010 19:54:51
This is a lava bomb from a shield volcano in southern Australia. This specimen is from my own collection.

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fericfdiaz.webs.com%2Flava_bomb_3a.jpg&hash=c97ea86aa12e0d2b8bff38224339ef33)
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fericfdiaz.webs.com%2Flava_bomb_3a.jpg&hash=c97ea86aa12e0d2b8bff38224339ef33)
Title: Geology In Pictures
Post by: Bass on 29/08/2010 05:39:55
looking down on the tops of basalt columns in tidewater, Giant's Causeway, Ireland


* DSC_0055.JPG (95.3 kB . 480x319 - viewed 5350 times)
Title: Geology In Pictures
Post by: LeeE on 29/08/2010 13:07:54
Some of the columns seem to be clearly separated from the ones beside them i.e. there seems to be a clear gap between some of them - is this so?
Title: Geology In Pictures
Post by: Bass on 30/08/2010 04:02:47
I agree.  Keep in mind the columns shown in the photo have been exposed to elements and undoubtedly weathered.  Basalt columns form as the lava cools and shrinks- the most efficient cooling shape being hexagonal.  A few more photos from Giant's Causeway:


* DSC_0016.JPG (110.93 kB . 480x319 - viewed 5364 times)

not sure which is better looking- these unique rocks or my daughter?
Title: Geology In Pictures
Post by: Bass on 30/08/2010 04:06:05
Basalt columns at the "Pipe Organ".  It's easy to see how these could erode down to the "steps" seen at tidewater.


* DSC_0132.JPG (92.27 kB . 480x319 - viewed 5360 times)
Title: Geology In Pictures
Post by: Bass on 30/08/2010 04:07:40
Like these:


* DSC_0038.JPG (111.96 kB . 480x319 - viewed 5285 times)
Title: Geology In Pictures
Post by: Bass on 30/08/2010 04:10:31
Fish out of water:


* DSC_0048.JPG (94.42 kB . 319x480 - viewed 5352 times)
Title: Geology In Pictures
Post by: Geezer on 30/08/2010 04:55:17
If you keep walking across the causeway, you'll come to this

http://en.wikipedia.org/wiki/File:Scotland-Staffa-Fingals-Cave-1900.jpg

(you might need a snorkel of course)
Title: Re: Geology In Pictures
Post by: Bill S on 21/10/2012 18:43:36
http://www3.hi.is/~oi/svalbard_geology.htm

That was a great link, Jim.  The Precambrian tillite, was specially interesting.  The picture was apparently taken by Jon Landvik, but one has to wonder if it was really John Wayne.  :)
Title: Some minerals...
Post by: Tomassci on 01/06/2018 10:28:59
Here is piece of some rock  [ Invalid Attachment ]
Here is microimage: [ Invalid Attachment ]
There is magnetite and propably quartz. Found somewhere.