Uluru EarthCache
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Access Central Australia accessible by car or tourist
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Uluru:
The Rock, Ayers Rock or Uluru was climbed by W.C Gosse in 1873 who
wrote “ The hill as I approached, presented a most peculiar
appearance, the upper portion being covered with holes or caves.
When I got a view clear of the sandhills, and was only two miles
distant, and the hill for the first time, coming fairly into view,
what was my astonishment to find it was one immense rock rising
abruptly from the plain; the holes I had noticed here were caused
by the water in some places forming immense caves”.
He named it Ayers Rock, after Sir Henry Ayers, the then Premier of
South Australia but since 1985 it has been known as its aboriginal
name Uluru. Gosse described the rock as a granite (an igneous rock)
whereas it is an arkose (sedimentary rock).
Despite this being a “big rock” there is a remarkable lack of
geological information for todays visitor.
Further Information
The following publication is for sale at some of the facilities in
the area and is highly recommended reading:-
Sweet, I.P,& I.H. Crick, 2003, Uluru and Kata Tjuta, a
geological history. Australia Geoscience publication (27 pages)
ISBN 0644 25681 8. First published ?before 1994.
If you can find it, a book called
“To Ayers Rock and Beyond” written by Bill Harney .....
gives an excellent account of both basic geological interpretations
as well as aboriginal spiritual interpretations. Bill Harney was a
famed bushman and storyteller and takes the reader on an intimate
and unique journey to Ayers Rock (Uluru) and many other places in
the remote Northern Territory. The book is based on his experiences
as the first Ranger of the Ayers Rock National Park commencing in
1957.
The following links provide various summaries of the geology of
the area.
Uluru - Kata Tjuta National Park Geology: Australian Government
publication
A potted
geological description courtesy Wayoutback Safaris
A simple
geological description courtesy Voyages Hotels and
Resorts
GEOLOGICAL PROCESSES The shaping of Uluru and Kata-Tjuta
(Modified after material suplied by Voyages Hotels and Resorts
website)
From a distance, Uluru looks smooth and featureless. But up close
its face is weather-beaten - pitted with holes and gashes, ribs,
valleys and caves. To Anangu people these features are related to
the journeys and actions of ancestral beings across the landscape.
On your tours and at the Cultural Centre in the Park, you may hear
about some of the Uluru creation stories. These stories, known as
Tjukurpa, tell about the travels and actions of Kuniya (Woma
python), Liru (poisonous snake), Mala (rufous hare-wallaby) and
Lungkata (Centralian blue-tongue lizard). You may learn to see the
evidence of their activities in the features of Uluru.
Geologists have different explanations about how these features
formed.
Creating the fans 550 million years ago the Peterman Ranges to
the west of Kata Tjuta were taller than they are now. Rainwater
flowing down the mountains eroded sand and rock and dropped it in
big fan shapes on the surrounding plain. One fan had mainly
water-smoothed rocks. The other fan was mainly sand. Both fans
became kilometres thick.
Pressing the fans Later, 500 millions years ago, the whole
area became covered in sea. Sand and mud fell to the bottom of the
sea and covered the seabed, including the fans. The weight of the
new seabed turned both it and the fans beneath into rock. The rocky
fan became conglomerate rock- this is the Olgas. The sand fan
turned into sandstone- this is Uluru.
Folding and tilting About 400 million years ago, the sea had
disappeared and the whole of Central Australia began to be
subjected to massive forces. Some rocks folded and tilted. The
rocky fan tilted slightly. The sand fan tilted 90 degrees so the
layers of sandstone almost stood on end.
Wearing away Over the last 300 million years, the softer
rocks have eroded away, leaving the parts of the old fans exposed.
Kata Tjuta is a hard part of the old rocky fan. Uluru is part of
the sand fan, with its beds of sandstone nearly vertical. The area
around Uluru and Kata Tjuta was covered in windblown sand plains
and dunes 30,000 years ago. Uluru, like Kata Tjuta, is the tip of a
huge slab of rock that continues below the ground for possibly five
to six kilometres.
The Ribs are formed by differential weathering. Some layers of
arkose, the rock that makes up Uluru, are softer than others, and
wear away more quickly. This leaves Uluru's characteristic parallel
ribs or ridges. Flaky red skin on the outside….. grey on the inside
Close up, much of the surface of Uluru is flaky red with grey
patches. The flakes are bits of rock that are left after water and
oxygen in the air have decayed minerals in the rest of the rock.
The red is the rusting of the iron in the arkose. The grey is the
original colour of the arkose. You can see the unrusted grey rock
inside the caves.
The Caves There are many types of caves at Uluru - those
that look like honeycombs, high up on the walls, and wave-shaped
caves at ground level. Perhaps they were formed by uneven flaky
weathering. Small pits became bigger dimples, then hollows, then
caves. Or they may have been chemically eaten away by water when
the land's surface was higher; then exposed as the land was eroded
away.
Carved out by water Water has shaped the valleys, potholes
and pools of Uluru. Rainstorm after rainstorm over millions of
years has sent water plummeting down the hard rock, wearing it away
to form grooves, and chains of potholes and plunge pools.
The Domes When the huge slab of rock that is Kata Tjuta was
being folded and faulted, vertical joints or fractures cracked
through the rock. Water seeped down the cracks and over millions of
years the rock eroded away - grain by grain, pebble by pebble, to
form valleys and gorges that split the rock slab into blocks.
Curved cracks called topographic joints formed on the surface of
the blocks. Weathering and erosion wore away the rocks above the
cracks to produce the rounded domes we see today. Kata Tjuta, the
Anangu name for the collection of domes, means "many heads".
To register this Earthcache you must visit certain
geographical co-ordinates (two are OPTIONAL) and collect the
answers to the following eight questions. If you elect to walk
around the rock you should heed all precautions for this journey
and allow 3-4 hours in the winter and more in the summer.
For further information on NOT climbing Uluru please visit the link
Australian Government notes "We do not climb Uluru"
Question 1 S25 20.564 E131 01.479 The camel is sometimes
referred to as the ship of the desert. What feature here could
mistakenly suggest you are near the sea?
Question 2 S25 20 29.3 E131 01 28.4 A feature here is
interpreted to be the result of topographic weathering. It is best
seen from a few hundred metres west. Why and what is it?
Question 3 S25 20.346 E131 02.709 What do you see up in the
rock face?
Question 4 S25 20.435 E131 02.807 The attitude of Uluru is
such that you are standing on something thought to be almost the
oldest of its kind in this area. What is it?
Question 5 S25 20.932 E131 03.080 What are laying south of
the footpath here and how did they get there?
Question 6 S25 21.182 E131 02.004 The spiritual
significance of many of the features of Uluru seem related to
geological and topographic features and are said to date back tens
of thousand years. Since the landform features are fundamentally
unchanged this indicates the erosional processes are quite slow.
What feature here indicates the presence of man?
Question 7 (optional) S25 20.740 E131 01.518 This is the
Start and the Ending of what? ( Note: Two types of white markings
are found on the rock around here. The natural markings are
believed to be formed by recent lightening strikes. Be
aware.)
Question 8 (optional) S25 20.692 E131 01.950 The Peak. What
is the significance of the phrase “Tear along the dotted
line?”
For further information on NOT climbing Uluru please visit the link
Australian Government notes "We do not climb Uluru"
Additional Hints
(No hints available.)