In fact, the rocks were silicate-rich.

"We've known for awhile that the Compton-Belkovich had an unusually high thorium content," Glotch said. "Now we can positively say that that thorium is related to these silicic volcano materials."

Volcanoes on the moon
Last fall, Glotch, working with another team, was the first to identify nonbasaltic volcanoes on the near side of the moon. Due to their highly reflective surface, this group was also originally noticed by the Lunar Prospector.

However, lava from the surrounding maria may have also concealed details of the volcanoes, so some details of the region's geologic history could have been hidden, researchers said. But the volcanoes on the far side have no maria nearby to hide their features. The complete view of the volcanism in the area lies open to examination.

Similarly, they are surprisingly free from impact craters, which reveals a great deal about their age, researchers added.

The early life of the solar system was violent, with rocks scarring the surface of the planets and their moons. Features that lack this scarring formed after things had calmed down.

Jolliff and his team estimated the age of the moon's rare far side silicate volcanoes to be about 800 million years old. Such an age would extend the volcanic activity of the moon by 200 million years, they said.

According to Glotch, the discovery of nonbasaltic volcanoes on the far side of the moon "shows that the moon is more compositionally diverse than we realized before this new age of lunar exploration."

"As scientists, we're still digesting all this relatively new data and working to understand what it means in terms of lunar history."

• Latest Moon Photos from NASA's Lunar Reconnaissance Orbiter
• LRO's Team Spirit with Joanne Baker
• Inside Earth's Moon

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7 Comments

1. 1. Didonai 08:10 PM 7/26/11

   Could such natural domes be modified and made habitable for human use? They might provide an ideal biosphere for human habitation...

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2. 2. EyesWideOpen 05:48 PM 7/27/11

   Using lava domes for life support habitats sounded like a great idea, so I looked up "lava domes" the wikipedia.org. Not only was there no indication that lava domes are hollow, but one statement seemed to indicate that ordinary lava domes may not be habitable. It states that the "sides of these structures are composed of unstable rock debris."
   
   The real candidate for underground habitation is the lava tubes, some the width of super guppies or greater. These structures are often stable and impervious to meteor impacts.
   
   You may be right because the Moon's low gravity may cause its lava domes to become hollow and produce a more stable dome structure, but that's speculation.

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3. 3. Quinn the Eskimo 10:09 PM 7/28/11

   "sides of these structures are composed of unstable rock debris."
   
   I'm curious. When, exactly, did the Wikipedia authors tour the lava domes on the far side of moon?
   
   Seriously, how could they possibly know about lava flows in a vacuum? Polaroid pictures from their extensive field expeditions? See?
   
   Be careful who your experts are.
   
   
   
   
   

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4. 4. EyesWideOpen 04:45 PM 7/29/11

   Actually I failed to clarify the wiki article was referring to terrestrial lava domes, and thus my added comment that gravity variations between Earth and Moon could make a difference in the stability of lunar domes.

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5. 5. EyesWideOpen 04:46 PM 7/29/11

   As for the lava tubes I mentioned, these were actually discovered through NASA (photos on NASA's site) via photographs fly-bys.

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6. 6. Cigarshaped 06:59 PM 7/29/11

   "The spacecraft found a number of domelike features with steeply sloping sides—telltale signs of lunar volcanoes."
   
   An alternative reason for domes has been seen on Earth for centuries, ie fulgamites. These are the effect of negative lightning striking metallic surfaces. Experiments with hv plasma discharge show dome-like protrusions with one polarity; craters are etched with the other polarity. I've had over 500 hits on my wiki-how webpage demo: wikihow.com/Etch-Your-Own-Crater.
   
   Perhaps in ancient times the moon suffered interplanetary discharge, which gave rise to her pock-marked appearance? That would also explain the silcates, which are by-products of high-energy electric discharge. Hence the glassy reflective coating to make the moon shine!

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7. 7. jonathanseer 07:44 PM 7/31/11

   I'm just wondering if the questions about lava domes on the moon being habitable are grounded in the mistaken assumption that these "lunar volcanic domes" are hollow inside, like the now gone "super Dome".
   
   Calling something a volcanic "dome" only refers to the "shape".
   
   Instead of having the classic sharp top, a dome volcano has a rounded top, with no discernible peak, but like a classic volcano it is solid, not hollow.
   
   Think of Mount St. Helens.
   
   Vulcanologists often speak of the "dome" growing in the ruins of the old crater.
   
   It is solid rock, or it will be once it completely solidifies.
   
   Venus has many of these, though their much bigger and flatter, and they too are solid rock.

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