Jonathan Stott wrote:
N_Cook wrote:

Pool freezing from outside to centre and ice expanding so free water
pushed up through the last remaining central hole until all frozen ?

This is correct. You can achieve a similar thing using distilled water
in an ice cube tray in a normal kitchen freezer. The water has to be
quite pure (or you have to be quite lucky) as impurities in the water
can block up the "growth".

There was something in New Scientist about this some time in the last
year or two!

Jonathan

Just read about this in New Scientist's book of experiments "How to
Fossilise your Hamster". Ice forms in the cracks and fissures of the
container first and then grows into the middle, forms a thin skin closing
inwards on the surface. The last little hole in the centre allows for water
to "erupt" out of the hole as the ice expands below forming a tube at first
and then solidifying. All takes about 10 mins... which seems pretty quick to
me.

They mentioned only ice spikes being formed this way, would love to see the
pictures of the petals!

Vb