Iraqi Kurdistan All in the Timing

harmless-looking, diffuse, groundhugging
mists. In reality, these are
blown snow blizzards whisked up by
fierce katabatic winds – the bane and
sometimes the nemesis of the early
explorers.
Dominating the entire view to the
south is the Ross Ice Shelf. This ice
sheet has an area the size of France and
landwards reaches a thickness of 700m.
Most spectacular of the ice-embedded
volcanoes was the perfect dome of
Mount Discovery. Close to the edge
of the permanent ice near McMurdo
Station a pod of orca or killer whales
were spotted as were, at a hopefully safe
distance, frolicking Emperor penguins.
At McMurdo’s Albert P. Crary
Science and Engineering Centre we
were shown lightweight, ‘wire wool’
textured phonolite bombs from Mount
Erebus, containing several centimetrelong
anorthoclase (an alkali-rich
feldspar) crystals known locally as
‘Erebus crystals’. These rapidly weather
out from their host bombs to collect
as loose whole crystals on the ground.
Their origin remains unknown, but they
are commonly present. For example,
long laths of anorthoclase in phonolite
were seen in pyroclastic boulders
scattered around Captain Scott’s hut
at Cape Evans. Informally these rocks
are known as Kenyte as they were first
described from Mounts Kenya and
Kilimanjaro volcanoes in East Africa.
The contents of Captain Scott’s Hut
are perfectly preserved by the ‘cold
store’ weather and tucked away in it we
found a geological laboratory
complete with a wet analysis
kit and rock samples. These
include a granite which must
have been collected from the
Transantarctic Mountains
during a sledge expedition.
Inexpressible Island
On the way to Ross Island
we entered Terra Nova Bay
in East Antarctica. The first
landing there, made in perfect
weather, was on Inexpressible
Island. This island, much
of which is a giant roche
moutonée, is formed of
wind-sculptured granites, partly buried
by glacial moraine, also essentially of
granitic origin. This landform, together
with others in the area, indicates a once
far thicker ice cover. The views were
completed by a scattering of Adélie
penguins and Weddell seals.
Of greater interest to any visiting
sedimentologist was a storm beach
boulder bed cemented by sea salt. This
lithology could only form in the stormy,
but desert climate that characterises the
inner Ross Sea region. Here there is no
rain and rarely more than windblown
snow. As such this rock could be unique
to the Ross Sea. Another unique feature
is that its components include boulders
of dumped sea ice.
The sole mainland visit was to
the nearby German research base of
Gondwana. The landing was achieved
in rough, albeit safe conditions, but a
An emperor penguin sledging at full speed across the ice. at full speed across the ice.
A boulder of anorthoclase-bearing phonolite erupted from
Mt Erebus. The anorthoclase (alkali-rich feldspar) ‘Erebus
crystals’ are several centimetres in length.
Nick Cameron
Jane Forsyth
rapidly strengthening katabatic wind
required a hasty retreat. Time did allow
an inspection of boulders and outcrops
of biotite gneisses. Granite pods are
perfectly exposed in nearby cliffs.
Deteriorating weather that day
prevented anything more than a
mist-shrouded view of the Drygalski
Ice Tongue. However, even that was
sufficient to reveal the scale and power
of this huge ice extrusion into the Ross
Sea. It is massive and strong enough to
trap Ross Ice Shelf icebergs against its
southern wall.
Epilogue
As the draft for this article nears
completion, the ship is again
approaching yet another volcano. In
total contrast to recent weeks, it is
warm with bright blue skies, with just
a residual swell from the last of those
endless depressions, but still replete
with so many gracefully skimming
albatrosses. And this time the land is
green; we are back in New Zealand
and the volcano is Lyttelton, near
Christchurch. In a professional life
often requiring field work for both of us,
this gentle scene provided the perfect
finale for cementing into our memories
a unique geological experience.
Acknowledgements
We would like to thank Heritage
Expeditions (www.heritage-expeditions.
com) for assistance with this article.
A longer version of this article, including
a look at Macquarie Island and the
Subantarctic islands, is available online
at www.geoexpro.com.
GEOExPro November 2015 81