We discovered this intriguing and beautiful rock when we were in
Raglan a couple of years ago. The rock is very large and almost
round. It is a totally different colour than other rocks nearby and
is covered with attractive swirls that appeared to be carved on the
surface.
We had both read the book “1421“. It tells of the
large treasure fleets of sailing ships which left China that year
and circumnavigated the world. Depending on who you believe the
book is pseudo science fiction or a record of events that require a
rewrite of history as we know it (of course, Columbus got to
America - he had maps). Parts seem totally reasonable; China traded
extensively throughout the Persian Gulf and had mines in Australia;
but those parts seem to be used as springboards for flights of
fancy; routes included waters well within the Antarctic circle
allowing an approach to New Zealand from the west and south and the
Arctic Ocean allowing a return to China from the east and
north.
According to “1421” some of the ships were wrecked
on the west coasts of NZ leaving behind proof of which one is a
solitary standing stone at Ruapuke Pa with carved inscriptions.
This stone gets a mention on the website megalithic.co.uk but the
GPS co-ordinates used are a car park for Ruapuke Beach. We asked at
the Raglan Visitor Centre and no one knew anything about such a
standing stone but one attendant told us about a tattooed rock and
added that it wasn’t known who made the markings.
We are not experts but believe the explanation for this enormous
anomaly is natural in origin rather than
archaeological and a very helpful staff member
of Auckland Museum has provided the most likely explanation. She
says “From the colour, the grain-size and the
hint of vesicles (holes) the rock is most likely an andesite and
volcanic in origin. The markings cannot therefore be fossil in
origin. However, I do still agree with you that they are natural
and wonder if they are snail trails. They could be made by either
marine snails adapted to the high tide zone, or perhaps even the
common garden snail.
Manu Beach is a very high energy beach and I imagine that
even the rocks in the upper zones will get wet from wave action or
salt spray during high tides and that this may encourage algal
growth, particularly on the southern faces away from the sun. The
smaller boulders are rolled around too much during high tide for
anything to survive on them, but the rock in your images is much
larger and therefore not likely to be moved during any but the
biggest storms.”
Andesite is an extrusive igneous,
volcanic rock, of intermediate composition, with aphanitic to
porphyritic texture. In a general sense, it is the intermediate
type between basalt and dacite. Andesite is typically formed at
convergent plate margins but may occur in other tectonic settings.
Intermediate volcanic rocks are created via several
processes:
Hydration melting of peridotite and fractional
crystallization
Melting of a subducted slab containing
sediments
Magma mixing between felsic rhyolitic and mafic basaltic
magmas in an intermediate reservoir prior to emplacement or
eruption.
Ultimately, the resultant composition of andesite and
intermediate magmas is the result of fractional crystallisation,
assimilation, partial melting and contamination by the subducted
slab. These may take considerable effort to resolve the individual
components.
In 2009, researchers revealed that andesite was found in
two meteorites (numbered GRA 06128 and GRA 06129) that were
discovered in the Graves Nunatak Icefield during the US Antarctic
Search for Meteorites 2006/2007 field season. This possibly points
to a new mechanism to generate andesite crust.
To claim this
Earthcache:
1.
Please take a photo of the top of the rock as similar as possible
to the photo above and post it with your log. The reason for this
is that the museum staffer suggested we chose one of the rock faces
as a reference and to take a series of photos over time, to see
whether the markings vary or whether they are static. If they vary
than they are obviously very recent in origin and most likely they
are snail trails. If not, then we may have to think of another
explanation.
2.
What do you think of the snail theory?
3.
Do you know anything about the Ruapuke Pa
menhir?
4.
Does the rock appear to have moved - use the location picture above
and the accuracy of the co-ordinates to answer this
question.