Distribution Tests
Although it has been claimed that numerous
examples of lumps of chalk were found covered in a uniform coating of glaze,
the only sample I ever managed to examine was that loaned to me by Nick
Riley and described in my first report (Second Sample). A
picture of that sample is reproduced in Fig 1. There was a more or
less uniform covering of glaze on the top of the sample. Two of
the vertical sides were also partially covered down to the base. There were
indications that the sides had lost large areas of glaze through abrasion. It was hard to explain how three mutually
perpendicular surfaces could have become covered in this way. In a simple test,
I sprinkled some
iron powder from a few centimetres onto a piece of chalk. Only the top
surface became coated, as can be seen in Fig 2. Note that there is no deposition at all on the
sides of the block.
Fig 1 Fig 2
During trials, I noticed
several features of the powder that could possibly account for this. When
the material was thrown onto the ground from approximately waist height, the air
turbulence that it created caused considerable dispersion of the powder as it landed.
It has to be remembered that the powder is heavy. A handful of
it descends rapidly creating its own swirling air currents. On
impacting the ground, eddies and turbulence in the air create a cloud
of the smaller particles which blows about for a few
seconds before settling.
A second feature is the splatter effect that propels quantities of the
powder sideways from the point of impact. I suspected that this
sideways movement of powder could account for the deposition of glaze on the
sides of the stones.
The
picture on the left, Fig 3, shows a test intended to evaluate the degree to which the
iron powder will distribute itself.
I took seven damp chalk pebbles and arranged them in a circle. I then took about
a level table-spoon full of powder in my hand and dropped it into the centre of
the circle from about 70 cm. The object of the exercise was to avoid
hitting the stones themselves but to place the point of impact of the powder
close by to see if the splatter coated the sides of the stones.
Note how the splatter effect caused dust to be ejected between the stones and
well beyond the ring.
Notice also a diffuse distribution of dust beyond the ring, particularly in the
top left quadrant. This was due to some of the powder adhering temporarily
to my hand and falling as a cloud, separate from the main body of the iron.
The pebbles were then carefully
removed and placed on a tray where they were subjected to series of damp/dry
cycles that mimicked, as closely as possible, the changeable and unsettled
weather that is believed to have preceded the finding of the H-glaze.
After 11 days, the period claimed to have elapsed between the creation of the
formation and its discovery, the stones were examined.
The pictures above show the top and side views of the stones. The stones
were rotated to show the sides that were innermost to the circle and
therefore exposed to the scattering powder.
The first impression is that
the coverage was very variable. Even though most of the stones were
initially well covered, as the test progressed, some thinning of the deposit
occurred due to various causes. Any accumulation of water on the
surface of the chalk caused the iron dust to coalesce and the dust was easily
removed by any movement of water over the surface of the stones.
The only way that the deposit could have stayed in place would have been a
prolonged period of damp conditions to allow the rusting process to begin.
The oxides created thereby would have formed a bond with the substrate and
become resistant to removal by a shower of rain. Even a moderate
shower in the early phase would have cleaned the stones completely.
Another surprising feature to emerge was that the iron powder could be very resistant to
rusting. I had expected the oxidation to proceed rapidly but it was
soon apparent that the conditions have to be just right for rusting to occur
within a reasonable period. This passivity could be due to a thin oxide
coating left on the surface of the iron by the manufacturing process. Such
a coating resembles the 'bluing' intentionally placed on steel items like
engineering tools and firearms which affords a measure of protection against
rusting. However, from the appearance of the iron dust, I would have
thought that such a coating, if it existed, could not have been thick enough to
make much difference. Even so, microscopic examination of the above
samples revealed a substantial amount of unconverted iron still present in the
deposits. This is significant as the original H-glaze also contained
elemental (unconverted) iron.
Despite the variability of these results, the distribution of the iron powder suggests that, given the right conditions, all exposed sides of some surface stones could have become covered. Most of the seven samples were coated down to their base and, in several cases, the undercut surfaces of the stones were coated. Also, this test was conducted with just one handful of powder. The original H-glaze was centred on the swirled regions of the formation which were 1 to 2 metres in diameter. An adequate application would have required several handfuls allowing ample opportunity for some stones to become completely covered. It should also be noted that, when the original samples were being collected, those that had a good covering would have attracted attention and been selectively chosen over those that did not. There is nothing to indicate that the stones collected were a representative selection of all the stones to be found within the swirled regions. Similarly, when Peter Sørensen was asked to recount events, he describes looking specifically for such examples and finding about 15 stones with varying degrees of coverage. There is no information to tell us how many stones were present with little or no coating.
On
the next page, I describe some tests on seed heads and demonstrate how the
iron dust managed to penetrate to the central stalk.