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3_WesternDistrict.html
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<title>Diamonds and Diamond Exploration
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<h1><a href="#">Grant's Diamond Pages</a></h1>
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<div style="text-align:center;height:400px;margin:auto";>
<br>
<h1>Volcanic Features of Victoria's Western District</h1>
<br>
<p>The volcanic plains of the Western District of Victoria (Australia) are
Recent in age and illustrate a variety of well preserved terrestrial volcanic
landforms. Local aboriginal legends record the eruption of some of the
volcanoes of the area. </p>
<p>The following descriptions are based on a field trip undertaken as part of
the "Volcanics Workshop 1984 - Continental Basaltic Volcanism ran by Monash
University (Melbourne) and convened by Dr Ray Cas, Bernie Joyce, Ian Nicholls
and Dick Price, from the 3rd to the 6th of
December 1984. The photos on this site were all taken by Grant Boxer and
edited for display on the web. The exposures are excellent and I recommend
that any geologist interested in volcanoes that is visiting Victoria, take the
time to see some of these great outcrops. With this in mind, I have
attached the excursion map (from the papers presented at the Workshop), and maps
of Lake Purrembete, and the volcanic complexes of Tower Hill, Mt Leura and Mt
Eccles. If additional information is required, please don't hesitate to
<a href="mailto:[email protected]">contact</a> me.</p>
<br>
<hr>
<h2>Location Maps</h2>
<br>
<img src="images/Volcanology/Localities_Map_620px.jpg">
<p style="text-align:center";>Location Map for the Victorian Western District Volcanic Field</p>
<img src="images/Volcanology/PurrumbeteMap_620px.jpg">
<p style="text-align:center";>Purrembete Maar</p>
<img src="images/Volcanology/TowerHill_Map_620px.jpg">
<p style="text-align:center";>Tower Hill Maar Complex</p>
<img src="images/Volcanology/MtLeuraMap_620px.jpg">
<p style="text-align:center";>Mount Leura Maar Complex</p>
<hr>
<h2>Maars</h2>
<br>
<p>Maars are typically large, circular and shallow craters that have formed by
phreatomagmatic eruption. Prof Volker Lorenz has written numerous papers
on maars and their formation and the reader is referred to
<a target="_blank" href="Bibliography.html#Lorenz, V">this</a> paper in
particular.</p>
<img src="images/Volcanology/24-02-Lake_Purdigulac_Maars.jpg">
<p style="text-align:center";>Lake Werowrap maars, Red Rock Volcanic Complex</p>
<img src="images/Volcanology/24-03-Lake_Coragulac_Maars.jpg">
<p style="text-align:center";>Lake Purdiguluc maars, Red Rock Volcanic Complex</p>
<img src="images/Volcanology/24-13-Purrambete_PhreatoMagTuffs1.jpg">
<p style="text-align:center";>Bedded tuffs in the rim deposits of the Lake Purrembete maar</p>
<img src="images/Volcanology/24-29-TowerHill_view_of_quarry.jpg">
<p style="text-align:center";>Interbedded phreatomagmatic and strombolian tuffs in the rim deposits of the Tower Hill maar</p>
<img src="images/Volcanology/24-30-TowerHillMaar1.jpg">
<p style="text-align:center";>View of the eastern part of the large Tower Hill maar</p>
<hr>
<h2>Phreatomagmatic Deposits</h2>
<p>The deposits of phreatomagmatic eruption are characterised by fine ash sizes,
high energy depositional environment for rim deposits, chilled magma clasts and
accretionary lapilli indicative of a wet eruption environment. Low angle
cross bedding in the maar rim tuff deposits is indicative of deposition during
high energy base surge activity where the surge is traveling outwards away from
the vent. In the photos taken in the Western District of Victoria, the
phreatomagmatic tuff deposits are typically light in colour due to their fine
grain sizes, and contrast to the darker colours of the strombolian type (fire
fountaining) of deposits where the tuffs are typically composed of scoria.</p>
<img src="images/Volcanology/24-07-Laminated_CrossBedded_Ash.jpg">
<p style="text-align:center";>Laminated and cross bedded ash, Lake Purdiguluc maar</p>
<img src="images/Volcanology/24-08-Phreato_Strom_Ashes.jpg">
<p style="text-align:center";>Phreatomagmatic ashes (lower light coloured tuffs) and strombolian ash (dark ash) at the Lake Purdiguluc maar</p>
<img src="images/Volcanology/24-16-PhreatoMag-tuffs-MtLaura1.jpg">
<p style="text-align:center";>Low angle truncations of bedding features in base surge deposits at the Lake Purdiguluc maar</p>
<img src="images/Volcanology/24-23-ScoriaClastsInTuff.jpg">
<p style="text-align:center";>Tuffs containing delicate scoria fragments at the Mt Leura Volcanic Complex</p>
<img src="images/Volcanology/24-25-Cross_Planar_Bedforms.jpg">
<p style="text-align:center";>Cross bedded and planar bed forms in phreatomagmatic tuffs at the Mt Leura Volcanic Complex</p>
<img src="images/Volcanology/24-33-TowerHill-Sandwaves.jpg">
<p style="text-align:center";>Sand wave bed forms and cross bedding in phreatomagmatic tuffs at the Tower Hill maar complex</p>
<img src="images/Volcanology/24-04-Base_Surge_Scour_Channels.jpg">
<p style="text-align:center";>Scour channel cutting base surge deposits at the Lake Purdiguluc maar</p>
<img src="images/Volcanology/24-05-RedRockComplex-ErosonGullies1.jpg">
<p style="text-align:center";>Detail of slide on left showing the scour channel and its infill, Lake Purdiguluc maar</p>
<img src="images/Volcanology/24-06-Detail_Scour_Channel.jpg">
<p style="text-align:center";>Close-up detail of the scour channel in photos on the left showing gravel lag in the base of the channel</p>
<img src="images/Volcanology/24-09-BombSag1.jpg">
<p style="text-align:center";>Volcanic bomb sag in tuffs at the Lake Purdiguluc maar</p>
<img src="images/Volcanology/24-11-Bomb_Sag3.jpg">
<p style="text-align:center";>Volcanic bomb sags in tuffs at the Lake Purdiguluc maar</p>
<img src="images/Volcanology/24-32-TowerHill_Bomb_Sag1.jpg">
<p style="text-align:center";>Volcanic bomb sags in tuffs at the Tower Hill maar complex</p>
<hr>
<br>
<h2>Scoria Cones</h2>
<br>
<p>The volcanic plains of the western Victoria have numerous conical hills that
comprise scoria cones. The Sugarloaf (see photo on left) is a classic
example that is found near Mt Leura. These scoria cones are produced by
fire-fountaining and where vesicular pyroclastics are deposited around the vent.</p>
<img src="images/Volcanology/Kilauea_1955-1.jpg">
<p>The photo above is from Hawaii (from geological Museum London) and show a
fountain of red-hot lava surround by a cinder (scoria) cone and a lava flow
leading away into the distance. </p>
<p> </p>
<img src="images/Volcanology/Surtsey1.jpg">
<p>The second photo (from geological Museum London) is from Surtsey (Iceland)
shows the effect of water on an erupting volcano. To the right of the
photo can be see the fire-fountaining producing the scoria cone material.
On the left the eruption cloud is white with steam and very violent, indicating
the interaction of water and the rising molten magma. The fragments in
this steam charged cloud are dark as they have been chilled by the contact with
water.</p>
<br>
<img src="images/Volcanology/24-19-Sugarloaf_Hill.jpg">
<p>Sugarloaf scoria cone from Mt Leura</p>
<img src="images/Volcanology/24-20-MtLeura_Maar_Rim1.jpg">
<p>Strombolian scoria deposits overlying light coloured phreatomagmatic tuffs at the Mt Leura Volcanic Complex</p>
<img src="images/Volcanology/24-28-Scoria_Bomb_Beds.jpg">
<p>Scoria overlying volcanic bomb beds at the Mt Leura Volcanic Complex</p>
<img src="images/Volcanology/24-47-MtEccles_Scoria_Quarry.jpg">
<p>Quarry in scoria at the Mt Eccles Volcanic Complex</p>
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