The Pleiades (volcano group) facts for kids
Quick facts for kids The Pleiades |
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 The Pleiades
Location in Antarctica
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| Highest point | |
| Elevation | 3,040 m (9,970 ft) |
| Geography | |
| Location | Victoria Land, Antarctica |
| Geology | |
| Volcanic belt | McMurdo Volcanic Group |
| Last eruption | 1050 BCE ± 14,000 years |
The Pleiades are a group of volcanoes in northern Victoria Land, Antarctica. This area has many young volcanic cones and lava domes. The most important volcano here is Mount Atlas/Mount Pleiones. It is a small stratovolcano made of three cones that overlap. It rises about 500 meters (1,600 feet) above the Evans Névé plateau.
Two other named cones are Alcyone Cone and Taygete Cone. Scientists have used special dating methods to show that Taygete Cone erupted during the Holocene (our current geological period). Ash layers found across Antarctica might have come from eruptions of The Pleiades. Some of these eruptions could have happened in the last few hundred years.
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Where are The Pleiades?
The Pleiades are located at the top of the Transantarctic Mountains. They are about 120 to 140 kilometers (75 to 87 miles) from the coast of Lady Newnes Bay in the Ross Sea. These volcanoes sit between the Evans Neve and the start of the Mariner Glacier. This glacier flows southeast from Evans Neve towards the Ross Sea.
The volcanic group is named after the Pleiades star cluster. This star cluster is found in the constellation Taurus. The name was given by the New Zealand Geological Survey Antarctic Expedition.
What do The Pleiades look like?
The Pleiades group has several steep, small volcanic cones and lava domes. They stick out from the ice of Evans Neve over an area about 13 kilometers (8.1 miles) long. Most of these cones do not have names.
However, some do:
- The central one is Taygete Cone.
- Alcyone Cone is just south of Taygete.
- Mount Pleiones (about 3,020 meters or 9,910 feet high) and Mount Atlas (about 3,040 meters or 9,970 feet high) are in the southern part.
Mount Atlas and Mount Pleiones together form a stratovolcano. This is the main volcano of The Pleiades. Mount Atlas itself is made of three separate cones. These cones rise about 0.5 kilometers (0.31 miles) above the ice. You can find lava and scoria flows on these cones. The youngest cone has a crater shaped like a half-circle. At the base of Mount Atlas, there are moraines, which are like ridges of rock and dirt left by glaciers.
Alcyone Cone is about 3.5 kilometers (2.2 miles) north of Mount Atlas. It is a bit lower than Mount Atlas but much smaller. It has two craters that are not very clear. It is mostly made of lava flows covered with loose rocks and volcanic bombs. Taygete Cone is about 6 kilometers (3.7 miles) north of Mount Atlas. It looks like a lava dome that has been changed by hot water. It also has a small crater.
The volcanoes look very young, which means they were formed not long ago.
How The Pleiades Formed
The Pleiades are part of the McMurdo Volcanic Group. More specifically, they belong to the Melbourne volcanic area. This area stretches from Mount Melbourne to The Pleiades. These volcanoes formed during the Cenozoic Era (a recent geological time). They are found in northern Victoria Land. Their positions might be controlled by deep cracks in the Earth.
Volcanic activity in this region started about 10 to 7 million years ago. Even older volcanic activity happened during the Cretaceous Period. This was when the West Antarctic Rift System became active.
The rocks under the volcanoes are very old. They include sedimentary and intrusive rocks from the Precambrian and Paleozoic eras. There are also major fault systems (cracks in the Earth's crust) near the volcanoes. These faults might have helped decide where The Pleiades volcanoes would form.
What are The Pleiades made of?
Scientists have found different types of volcanic rocks at The Pleiades. These include basanite, basalt, hawaiite, phonolite, and trachyte. These rocks suggest there were two different types of magma (molten rock) that were rich in sodium and potassium. These magmas might have come from different levels of the same magma chamber deep underground.
These magmas originally came from the Earth's mantle. They changed as they moved up through the Earth's crust. The Pleiades volcanoes show one of the most complete sets of magma types in the McMurdo Volcanic Group.
When did The Pleiades erupt?
The oldest eruptions found happened about 825,000 years ago. These eruptions created trachyte rocks in the central part of the area. Even older eruptions might have happened, but they are now buried under snow and ice.
Scientists have used different dating methods to find the ages of the rocks:
- Some rocks on Mount Atlas are less than 100,000 years old.
- Lava flows on Alcyone Cone are about 45,000 years old.
- The youngest ages, around 6,000 to 3,000 years ago, have been found on Taygete Cone. This suggests The Pleiades are quite young volcanoes.
Ash deposits (called tephra) have been found in different parts of Antarctica. Some of these might have come from The Pleiades. These include ash layers from:
- About 50,000 years ago near Frontier Mountain.
- Several tens of thousands of years ago near Lewis Cliff.
- 26,000 to 22,000 years ago in the Ross Sea.
- 16,000 to 15,000 years ago in Talos Dome.
- A layer of volcanic glass at Siple Dome from around 1286 to 1292 AD.
- Ash layers in ice cores that date to 1776 to 1885 AD. One layer at Siple Dome is from about 1809.
- A big eruption might have happened between 1880 and 1980, either at The Pleiades or Mount Melbourne.
Today, only small amounts of fumarolic activity (steam and gas vents) have been reported. Future eruptions are possible, but The Pleiades are not watched by scientists. They are also very far from any research stations.
