The Formation Of A Forest... EarthCache
The Formation Of A Forest...
-
Difficulty:
-
-
Terrain:
-
Size: 
(regular)
Please note Use of geocaching.com services is subject to the terms and conditions
in our disclaimer.
The
Formation Of A Forest...
Welcome to another Blacklegend cache hide. This is my 99th
cache, and my 3rd Earth Cache. hide.
I wanted to place a cache based on one of these mighty trees, and
its relationship to the Murray River System, in particular, the
formation of the Barmah State Forrest some 8 to 15,000 years ago.
So, while out placing a few traditionals, I came across this huge
example of this type of tree. So, what type of tree is it. Well it
is a River Redgum (Eucalyptus camaldulensis).
A bit of information on River Redgums...
Ok, I am going to give some information on River Redgums first.
River Redgums can be found across much of Australia. Found often in
"Pure Stands" where the only tree type is the River Redgum. Below
is an image of the range of the River Redgum. As you can see, it is
extensive.
Further to that, River Redgums are used in other countries for a
variety of reasons, one being that it is a very fast growing
timber. A list of countries and places include:Plantations occur
in Argentina, Arizona, Brazil, Burkina Faso, California, Egypt,
Kenya, Morocco, Nigeria, Pakistan, Senegal, Sierra Leone, Spain,
Sri Lanka, Sudan, Tanzania, Uruguay, and Zimbabwe. This list is
by no means complete.
River Redgums can live to between 500 and 1000 years of age, and
often after a certain number of years (between 120 and 180 years),
hollows are formed, which provide habitats for wildlife like native
marsupials and native birds. The trees can grow up to 45 meters
high in the oldest samples of these trees. The tree which is near
where I have brought you to for GZ, took 3 fields of the iPhone
camera to take, and the image was stitched together. I would
estimate its height standing near it at somewhere between 35 to 40
meters. It is certainly one of the tallest samples I have
seen.
River Redgums can survive extensive periods of flooding, with even
saplings able to survive for months with the roots underwater. The
trees can shed leaves and branches in periods of drought to
conserve water loss, making it extremely hardy.
The Formation of the Barmah-Millewa
Forest...
Ok, so why did I bring you to this spot??. For one, parts of the
Barmah-Millewa State Forest are often closed due to flooding, the
exact conditions that River Redgums thrive in. Terrain ratings
would be 4 to 5. So I brought you to this spot, which displays a
similar landscape to the Barmah-Millewa Forest, with better
accessibility. Also, the Barmah - Millewa State forest is a
Wetlands, and again, Terrain would be very difficult.
A bit of background and information and Geological
History.
Thousands of years ago the Murray flowed north of Echuca, along the
course of what is today called Green Gully. It did not flow through
the Echuca area.
The Cadell Fault Line runs from near Deniliquin south toward
Elmore. At various times over the last 35,000 years, land to the
west of the fault line has been uplifted, blocking the flow of
westward flowing streams and rivers.
There have been two major events. The first about 35,000 years ago,
an area of land to the west of the Cadell Fault Line was uplifted,
blocking the Goulburn River and leading to the formation of Lake
Kanyapella, a remnant of which remains (the present-day Kanyapella
Reserve). The Goulburn River escaped by flowing into the Campaspe
River. It abandoned its old course which today is called Broken
Creek. Broken Creek flows into the Murray immediately downstream of
Barmah Lake.
The second major event took place about 16,000 years ago. Tectonic
activity caused the land to the west of the present Barmah-Millewa
Forest to be uplifted by between 8 and 12 meters along the fault
line. The uplifted block of land slopes down to the west (the
Cadell Tilt Block). This uplift caused the Murray river to change
its course to the South, and flowing around the Cadell Tilt Block.
The Murray River now flows through Echuca and then obviously West
into South Australia.
This change in course of the Murray River caused it to flow through
an area between Moira and Barmah Lake. This used to be one large
lake. The area the Murray river flows through in this area is
called "The Narrows" and is actually higher than the lake on both
sides. A series of natural levees allow this to happen and also
result in flooding into the Millewa and Barmah Forests. This
flooding provides the level of water provided to sustain the Redgum
Forests, as rainfall alone is not enough to sustain a forest of
this size. Local flooding into the flood plains where this cache is
located, helps sustain the redgum forests in this area, as once
again, the rainfall is not enough.
The information sources below will assist in answering the
questions for this Earthcache. The links are very informative, and
will provide more information than you need. However, it is
fantastic reading.
Wiki Link -
River Redgum
Barmah-Millewa
State Forest
Barmah Choke History
What to do to claim a find on this Earthcache..? You will
need to answer the questions below, and email me before logging
your find. The questions are easy, but, you will need to answer one
question to prove you were there... A photo is not required, as per
the guidelines, but if you want to post one, that would be
fantastic. ON WITH THE QUESTIONS.
Question 1. Looking at the map above, which mentions the Cadel
Tilt Block and Fault, what was the major effect to the waterways
which would have traveled through the area where the Cadel Tilt
Block is now?
Question 2. You will have to read the links to find the answer to
this question. Which river was created due to the formation of the
Cadel Tilt Block?
Question 3. At the cache location, have a look around. What do you
see? Remember this area is a Redgum Forest as well. Would this area
likely flood at various times?
Question 4. Read the page called "Barmah Choke History". About how
many thousand years ago did the Murray River start heading south?
What river system did it take over? What was created as a result of
this?
Question 5. To prove you were at GZ, take a look at the big Redgum
tree (same as in the cache page pic). At about chest high, measure
around the circumference of the tree. What is the circumference in
meters, nearest half meter will do.
As always with my caches, and
anywhere in Australia, beware of Snakes. I would think that there
would be heaps in this place in warmer months. With parental
supervision, take the kids, just keep an eye on them with the
snakes. In the winter months, a 4WD vehicle may be required to
access this location, hence the 3 terrain rating. Most importantly,
HAVE FUN.
Additional Hints
(Decrypt)
Lbh jvyy arrq n zrnfhevat gncr sbe guvf pnpur. Frr dhrfgvba 5.