[Geysers] Colour changes and colour effects in thermal features

[Janet Chapple]

How nice to be reminded of the New Zealand thermal area I loved most 
when there in 2003. Inferno was very steamy when I was there. Frying 
Pan and the whole area were beautiful. I put some pictures and a little 
information on my Web site at:
http://www.yellowstonetreasures.com/rotorua.htm

I would be interested to know whether your experiment with red dye 
*did* show a connection between the two lakes.

Janet Chapple
-------

On Dec 12, 2006, at 6:25 PM, Ron Keam wrote:

> Pat Snyder's contrasting photographs of Pearl Geyser show probably
> the most dramatic change I have ever seen in the colour of a
> geothermal feature (apart from occasions when formerly transparent
> water has become clouded due to some stirring of sediments).
>
> In 1951 Frying Pan Lake at Waimangu was almost an indigo colour and
> the water was clear enough for a submerged crater rim to be quite
> clearly visible.  By the late 1960s the water had assumed a greener
> tinge and was much cloudier.  Only once in recent years have I seen
> it clear again and that state did not last.  The hinterland at
> Waimangu was turned into farms in the late 1950s and I can believe a
> suggestion made to me that the effect has been produced by run-off of
> fertiliser that had been liberally spread there to increase
> agricultural productivity in what formerly had been a very lightly
> vegetated pumice soil.
>
> Inferno Crater Lake changes cyclically in colour in synchronism with
> its level changes - when the water is rising it is very turbid and a
> very pale brown colour; during a main flow it is blue but mostly
> difficult to see because of the dense steam-clouds hiding it; during
> the long recession after a main flow it clear and the most intense
> turquoise colour.  The muds being deposited within the Inferno Crater
> basin were brilliantly snow-white in the 1950s.  Now they are a
> rather less attractive light brown.  (Once when I was conducting an
> experiment to test its possible interconnection with Frying Pan Lake,
> Inferno Crater Lake was artificially turned red with Rhodamine B
> flourescent dye.  Afterwards the dye adhered to the mud flocculating
> in the water, and deposited out as a distinct band which persisted
> for a few years.  It all disappeared long ago.)
>
> Those of us who were privileged to be taken in Rick Hutchinson's boat
> out onto Grand Prismatic Spring saw some of the clearest water in any
> thermal spring that I have ever seen.  The rocks at the bottom
> started off in the shallower regions appearing green, and gradually
> as the depth increased they appeared to be bluer and bluer, and
> ultimately becoming almost indigo and the bottom became invisible.
> The contrast with the waters in Frying Pan Lake and Inferno Crater
> Lake was very distinct.
>
> There is a very green lake in one of the craters of the Waiotapu
> thermal area near Waimangu.  This lake has the Maori name Rotowhero
> which means "Red Lake".  One should not suppose that the name was
> applied by a colour-blind person, because there are significant
> deposits of red mud around, and the supposition is that the name was
> originally given when this mud had been stirred up in the lake waters.
>
> Ron Keam
>
>> Thank you, Stephen, for mentioning the color change in Pearl. Here
>> is a picture "before" (September 2004) and "after" (September 2006).
>> Both are beautiful in different ways, but I do miss the blue
>> opalescence.
>> Enjoy.
>> Pat Snyder
>>
>> Sept. 2004:
>>
>>
>> Attachment converted: Macintosh HD:pearl9.9.04web.jpg (JPEG/8BIM) 
>> (00120AEB)
>>
>> Sept. 2006:
>>
>>
>> Attachment converted: Macintosh HD:pearl9.6.06.jpg (JPEG/8BIM) 
>> (00120AEC)
> -- 
>
>
> #####################
> Ron Keam
> The Physics Department
> The University of Auckland
> Private Bag 92-019
> Auckland
> New Zealand
> Phone +64 9 373-7599 extension 87931
> FAX +64 9 373-7445
> EMail r.keam at auckland.ac.nz
> #####################
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