Sat. Jan 29th, 2022

One of the couple of tell-tale indications is the presence of rafts of light pumice stone floating on the sea surface after being blown out of a submarine volcano. Rather it is possible that volcanoes have actually continued to grow or brand-new ones formed long after the original structure.

Credit: Phil Vandenbossche & & Nelson Kuna/CSIRO
Appearing like the Eye of Sauron from the Lord of the Rings Trilogy, an ancient undersea volcano was slowly revealed by multibeam sonar 3,100 meters below our vessel, 280 kilometers southeast of Christmas Island. This was on day 12 of our trip of exploration to Australias Indian Ocean Territories, aboard CSIROs dedicated ocean research study vessel, the RV Investigator.
Previously unidentified and unimagined, this volcano emerged from our screens as a huge oval-shaped depression called a caldera, 6.2 km by 4.8 km throughout. It is surrounded by a 300m-high rim (resembling Saurons eyelids), and has a 300 m high cone-shaped peak at its center (the “pupil”).
Finder picture of the Eye of Sauron volcano and neighboring seamounts on the sea bed south-west of Christmas Island. Credit: Phil Vandenbossche & & Nelson Kuna/CSIRO
A caldera is formed when a volcano collapses. Typically, a small brand-new peak then begins to form in the center as the volcano continues spewing lava.

Here is the geological conundrum. Our caldera looks surprisingly fresh for a structure that should be more than 100 million years old. Ered Lithui has practically 100m of sand and mud layers draped over its summit, formed by sinking dead organisms over millions of years. This sedimentation rate would have partly smothered the caldera. Rather it is possible that volcanoes have actually continued to sprout or new ones formed long after the original structure. Our restless Earth is never ever still.
The large deep-sea predatory seastar Zoroaster. Credit: Rob French/Museums Victoria
Life adapts to these geological modifications, and Ered Lithui is now covered in seafloor animals. Brittle-stars, worms, crabs, and sea-stars burrow into or skate over the sandy surface. Erect black corals, fan-corals, barnacles, sponges, and sea-whips grow on exposed rocks. Gelatinous cusk-eels prowl around rock gullies and boulders. Batfish lie in wait for unsuspecting victim.
Little batfish patrol the seamount summits. Credit: Rob French/Museums Victoria
Our mission is to map the seafloor and study sea life from these ancient and remote seascapes. The Australian government recently announced plans to create two massive marine parks throughout the regions. Our exploration will supply clinical data that will assist Parks Australia to handle these locations into the future.
Elasipod sea cucumbers eat natural sediment on deep sandy seafloors. Credit: Rob French/Museums Victoria
Scientists from museums, universities, CSIRO and Bush Blitz around Australia are taking part in the trip. We are close to finishing part one of our journey to the Christmas Island region. Part two of our journey to the Cocos (Keeling) Island area will be scheduled in the next year approximately.
No doubt many animals that we find here will be new to science and our first records of their presence will be from this region. We expect a lot more surprising discoveries.
Written by Tim OHara, Senior Curator of Marine Invertebrates, Museums Victoria.
Originally released on The Conversation.

A caldera is formed when a volcano collapses. The molten magma at the base of the volcano shifts up-wards, leaving empty chambers. Typically, a little new peak then begins to form in the center as the volcano continues gushing lava.

One popular caldera is the one at Krakatoa in Indonesia, which took off in 1883, killing 10s of thousands of people and leaving only bits of the mountain rim visible above the waves. By 1927, a little volcano, Anak Krakatoa (” child of Krakatoa”), had actually grown in its.
In contrast, we may not even know volcanic eruptions when they occur deep under the ocean. One of the few tell-tale indications is the existence of rafts of light pumice stone floating on the sea surface after being burnt out of a submarine volcano. Ultimately, this pumice stone becomes waterlogged and sinks to the ocean flooring.
Our volcanic “eye” was not alone. Further mapping to the south exposed a smaller sea mountain covered in numerous volcanic cones, and even more still to the south was a larger, flat-topped seamount. Following our Lord of the Rings theme, we have nicknamed them Barad-dûr (” Dark Fortress”) and Ered Lithui (” Ash Mountains”), respectively.
The voyage of the Recreational Vehicle Investigator around Christmas Island. Credit: Tim OHara/ Museums Victoria
Although author J.R.R. Tolkeins understanding of mountain geology wasnt ideal, our names are incredibly proper provided the rugged nature of the first and the pumice-covered surface of the 2nd.
The Eye of Sauron, Barad-dûr, and Ered Lithui belong to the Karma cluster of seamounts that have actually been formerly approximated by geologists to be more than 100 million years of ages, and which formed beside an ancient sea ridge from a time when Australia was positioned much even more south, near Antarctica. The flat summit of Ered Lithui was formed by wave erosion when the seamount extended above the sea surface, prior to the heavy seamount gradually sank pull back into the soft ocean seafloor. The top of Ered Lithui is now 2.6 km below water level.


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