Wednesday, January 8, 2020

SearchResearch Challenge (1/8/20): Mysterious rainbows and fossils in the floor?

We live in a remarkable world... 

.... if only you take the time to notice it.  Here's an example of what I mean.  

The other day as I was walking into work, it had been raining, and we had a glorious rainbow.  Here's my photo of that memorable walk.  The brick and glass building is my place in the Google-verse.  

(Yes, that's the green of the golf course that's next door to the Google offices.)  

As beautiful as that walk was, I was actually slightly more surprised when I saw another rainbow pattern... this time inside... on the marble floor.  That rainbow looked like this: 

I haven't done anything to this photo (no Shopping or anything)--that's really the way it looked as I was walking down the corridor.   (Note that this photo was taken a couple of hours after the previous rainbow-in-the-sky pic. It had stopped raining by then.)

If it helps, this is the view to the west--looking in the opposite direction of the previous rainbow.  And there's no oil or anything on the floor--it's clean and dry.  As you can see, there are FOUR different rainbow patterns here--and I found that to be fairly amazing.  Why?  

Interestingly enough, that same section of floor also holds another couple of mysteries.  See below.  These pictures are taken from the section of the floor that has the rainbow pattern on it.  (I don't think there's any connection here--lots of the floor in this building has these patterns.)  

As I walked around, I could find these strange spiral/horn-shaped things in the marble flooring.  

Even more remarkably, I asked a few folks who also inhabit my building about these things, and nobody seems to have noticed!  Zounds!  There are mysteries literally underfoot!  

So I'll put these questions to you, my faithful SearchResearchers...

1.  What's causing the rainbow effect on the floor in the photo above (#2)?  Any ideas?

2.  What ARE those things in the floor?

If you know off the top of your head, that's fine (but say so... and then give us a link to a credible resource that supports what you're saying).  

But for everyone else, be sure to tell US the search path you followed to figure out the answers.  

(I'd love to understand what's going on in the floor beneath my feet!) 

Search on! 

PSA: My book, The Joy of Search, is now available at fine booksellers (and online)!  


  1. Anne and Deb here. We thought the first question would be fairly straightforward but we are finding it pretty difficult. We started doing a search for windows sun rainbow. Most of the results talked about how rainbows are created by rain droplets. Those results didn't help. There was one from a site called mattress clarity - which we wouldn't have considered the most reputable that did do a good job of explaining light coming through windows but while it mentioned how rainbows are created in nature by water it didn't really explain the phenomena of rainbows in windows. It did give an explanation of refraction which is what we think is going on. But still weren't getting the answer we thought should be easy to find. We theorized that the window must somehow be bending the light so maybe the window was beveled or had different thicknesses of glass. We didn't think we were going to be able to go any further without some help so we reached out to the AP Physics teacher in our school! To be cont.

  2. Part 2. We met up with the physics teacher and Dan he had some ?s He wanted to know what time of day it was and if it was exactly due west (or pretty close). We were surprised that he was actually a little stumped himself. He said it was the process of refraction but wanted more time to research. We are up for that. We are going to move on to question 2. Hopefully that will be easier.

    1. It's pretty close to due west. And the photo was taken at 2:47PM PST. Does that help? (I admit this is a bit tricky...)

    2. I checked: The compass angle is 280 degrees (WWNW). Useful to know that due west is 270 degrees, due north is 0, etc.

    3. Dan thanks will report that back to our physics teacher! Hoping we will learn something in the process!

    4. Dan another question from our physics teacher. Do the windows have beveled edges (I actually thought of this too!) Don't think I can post an image in a response but think you get the idea about beveled edges.

    5. Nope. Just flat edge to edge.

    6. Ok will post answer we got from our physics teacher Dr. Anthony Danese below!

    7. Ok Deb and Anne here back to respond to the rainbow question after going to our AP physics teacher, Dr. Anthony Danese (for those of you who don't know us Anne and I are librarians at Morristown High School in NJ). Anthony was really excited about this challenge and it was fun working with him. So his initial reaction was that the glass might be beveled in some way but found out from Dan that no it wasn't. Next thought that Anthony had was that the glass was either polarized and/or the window was stressed in some way which would also cause it to have different angles/surfaces that would produce the rainbow effect. We also both wondered if there was some kind of film on the glass that was causing the polarization. Anthony found this website which he thought best explained the effect - As best as my very unscientific brain absorbed what was stated it was a combination of the sun coming through the glass with some possible stressors causing differences in surface hitting the floor which then reflected the light causing the polarization effect. Will post comments about this challenge in separate entry.

    8. Comments to this challenge. While this really really stretched our (Anne and me)limits we loved this challenge. It was great reaching out to a colleague and watching him get very excited about something he didn't know off the top of his head in his field. It was fun listening to him explain the process and to hear how he researched this. So keep these interesting challenges coming!

    9. Thanks for this, Deb, Anne and Anthony!

      I'd love to hear a bit about how Anthony did his research. Are there lessons we could learn from what he did?

    10. Will ask him to share his search strategies!

  3. On to question 2. Those shapes looked like fossils to us so did a search for spiral/horn-shaped fossil in marble. Found that these things are known as ammonites (did we have this in another search? It seems familiar to me). That brought up several sites where you could buy marble flooring with these fossils in them. Our search for those results was ammonite marble flooring. I wondered if there was a reason this tile was chosen. I wondered if Google being such a forward looking company wanted something to show that they were grounded in history. Anne thought the better explanation was that it was expensive and trendy. We did find a site which talked about the design of the Googleplex - It was a really interesting read but didn't specifically mention the marble flooring. There is an office with a game with marbles in it. But that was only mention of marble. There was mention of other types of flooring.

    1. I suspect Anne is right. These particular buildings weren't built for Google, but for Alza (a big pharma company). We got them from those folks.

  4. had little time, so took a flyer — can't verify the uni, but have heard that Larry & Sergey like them to be around to stir up the pixie dust… all anecdotal…
    Taking control of anisotropy
    perhaps this is an alternate explanation for the 'Plex phenomenon…? heard they are common, but rarely seen —
    and even rarer to photograph…
    they come in many forms, but all share the horn…

    "Fossil Marble quarried from an ancient seabed in the Mediterranean"
    Hezhra Small Fossil (medium gray)?? Morocco?
    examples - flooring supplier… Straight (or Stack Bond)

  5. Good Morning!

    When I look the floor's photos, thought about fossils and remembered Tepexi de Rodríguez. I went there many years ago. I don't remember a lot. It was a good experience and, in that moment, if you find a fossil you could keep it

    Tepexi de Rodríguez cantera Tlayúa Quarry Fossils

    In Spanish, more about the fossils and the quarry:LA CANTERA DE TLAYÚA. UN SITIO PALEONTOLÓGICO EXTRAORDINARIO

    Fossils:Fósiles marinos en Tepexi de Rodríguez - Tlayúa Video with English captions

    Some photos

    About Q1, not sure if there are connected with the fossils, I don't think so. Also not sure if the rainbows happen because of the rain or because of the light. Dr. Russell, have you seen those other days? at same hours? I was searching about rainbows and their causes. And I think the color can give us some answers.

    Out of topic: Popocatepetl, this morning. Beautiful! Sorry I missed it

    1. I just read this interesting article. Maybe Dr. Russell thinks more SRS Challenges related to Birth place of dollar

  6. I thought the rainbow effect would be due to some coating or film on the window …. probably, since it’s west-facing, to reflect infrared heat to the outside of the window, which would help keep the building cool on hot afternoons. So I searched for [window rainbow coating film]. My results were dominated by decorative rainbow-producing films that one can buy and place on windows … not what I was looking for. So I removed “film”. But got essentially the same results. To make any progress, I had to minus “film” ([window rainbow coating -film]. (As an aside, I wish Google search results did not have such an results-inertia effect.)

    Oddly, the first useful result described the rainbow effect in oven door glass (

    < < <
    A rainbow effect in Wolf electric or gas glass oven windows result from a tin oxide coating placed on the inside of the glass.
    • The coating is used to reflect radiant energy or heat from the interior back into the unit.
    • This helps maintain a cooler oven door exterior temperatures.
    • This is a normal condition.
    • Replacement glass parts will have the same rainbow appearance or condition.
    < < <

    [window "rainbow on the floor" "energy efficient glass"]

    found a glass catalog ( that described rainbow-like effects called Brewster fringes:

    > > >
    Brewster’s fringes are a visual effect seen as a rainbow visible within an IGU (Insulating Glass Unit). Brewster’s fringes are not a deterioration of the unit or glass but an effect created when light passes through two panes of glass of the same thickness, the resulting light refraction becoming visible as a rainbow effect. Brewster’s fringes can be confirmed by pressing one surface of the unit. The rainbow effect will move and colours change as the one glass surface is depressed and released. Brewster’s fringes are normally avoided by using different thickness of glass for each pane of the IGU.
    < < <

    Another ( said Brewster’s fringes can occur when “high quality float glass is used with surfaces which are optically flat and both panes of glass are parallel in the IGU. Light reflected within one glass can combine with that similarly reflected within the other, with such small path differences as to cause interference. The effect is of faint colored bands or irregular shapes, which can be located anywhere over the surface. It is rarely noticeable in normal lighting conditions.”

    While it seems that Brewster’s fringes are seen in the glass, I wonder if it – perhaps in combination with heat-reflecting coatings -- produced the rainbows on the Googleplex floor.

    On the other hand, this technical dictionary “ says Brewster’s fringes are “oily looking” … which I wouldn’t think describe yours, so maybe that not the cause.

    BTW, ["diagonal rainbows on the floor" "energy efficient window"] found nothing.

    Possibly this is related to the solution. But possibly not, because they appear in the glass and perhaps not transmitted to the floor.

  7. 1. My guess was that the windows are polarized so I searched "rainbow through polarized windows" and found this article:
    which says: "As for the rainbows in car windows, this is also an effect of stressed birefringence.Incident light from outside the car passes through the rear or side windows. The stresses caused by the tempering rotate the polarization. The amount of rotation depends on the wavelengths, thus resulting in the varied colors. Again, what you’re seeing is the stresses in the car window caused by the tempering process."So I assume the windows at you workplace are tempered glass.

    2. OK, so I knew that to be a fossil in the floor.  I tried to search without that information, but didn't get very far.  I searched "fossils in flooring" and found a fun video from the Field Museum images, I found a few fossils to match and one identified it as an ammonite fossil.  According to this site ( ) they are named after the Egyptian god Amun (for the rams horns on his head).

  8. Having studied Geology as an undergrad and Masters, number 2 was easy. That's an ammonite. This makes the search easier because I can look for "ammonite floor tile", leading to a similar image in flickr from flooring in an Annapolis Mall

    Ammonites were fascinating and diverse creatures, and went down with the dinosaurs at the end of the Cretaceous age. the related living survivor is the Nautilus, some interesting research as to why these species made it through an extinction event

    What's even more interesting about these spiral mollusks is the mathematics of their shell form; I remember from Geology the work by D'Arcy Wentworth Thompson "On Growth and Form" who showed these shells are defined by the math of the Golden Spiral (I think the ammonite was on the cover of my copy of the book).

    Finally, your building floor is likely not marble but limestone (marble is metamorphosed limestone, the heat and pressure under which it is formed would break down fossils). Limestone is a very durable building material (used ito build both the Egyptian pyramids and the Pentagon).

  9. We may be missing something about question one. Not based on research, but on my general knowledge of science the refraction of light is caused by changes in the material and angle at which light passes through. If this was indeed just a perfectly flat glass window this pattern shouldn't be possible. It is my suspicion the there is either a distortion of the glass or some sort of film on either the window or floor.

    In regards to the second question I found some interesting information. I started by searching for "spiral fossil in marble" and quickly found that fossils don't exist in marble. Since marble is a metamorphic rock it has been heated and pressurized beyond what a fossil could take and retain its shape. I then removed marble from the search terms and found that the fossil imprint is most likely an ammonite fossil. Ammonites are relatives of squid and octopus. The fossil existing in the floor tiles means that they are either limestone tiles or they are marble imprinted with the fossil shape for aesthetics.

  10. 1) I thought I knew how to phrase my search terms, at first. But it was only when I stumbled across an article in Eureka: posted today that I realised the term I needed was IRIDESCENCE. Good enough for hummingbirds guessed that term would be good for window glass coloring.

    Indeed [window iridescence] finds this What is iridescence (anisotropy) and 5 ways to reduce it in tempered glass. This explains the rainbow colors on the floor.

    2) The ammonites: These I knew right off. Now a nice feature is this fossils in the architecture of washington, dc. Gallery 15 mentions ammonites. Critters that lived from about 400 million years ago to maybe 100 million.

    Cheers jon tU

  11. turn bright-red tomato juice into a rainbow of color:

    yumyum j

  12. My previous SRS report seems to have got lost in a snowstorm and I did not save a copy; so here goes a re-creation.

    On stumbling across an article in Eureka about how humming birds got their colors I was struck by the word iridescence. Seens to me this explains the window situation, [iridescence window] finds

    Wikipedia knows about this too: Iridescence - Wikipedia
    Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear to gradually change color as the angle of view or the angle of illumination changes. Examples of iridescence include soap bubbles, feathers, butterfly wings and seashell nacre, as well as certain minerals.

    The critters in your limestone floor tiles are ammonites. They lived long before the WWW was invented. My grandson Sam found a very nie speciman near here when he was about 8 years. We extracted it from the limestone river bed and took it to the paleontology museum for confirmation. They liked it so much they asked him if they could keep it. Its still there.

    Good clean fun on this one. jon tu