When we discuss impressive geological functions, we usually restrict ourselves to those in the world. However as a rock hound, I believe that’s insane—there are numerous frameworks on various other globes that can delight and also influence, which can place procedures on our very own world right into point of view.

Right Here, in no certain order, are the 5 geological frameworks in the (leaving out Planet) that the majority of excite me.

The grandest canyon

I omitted the planetary system’s greatest volcano, Olympus Mons on Mars, so I might consist of that world’s most amazing canyon, Valles Marineris. Being 3,000 kilometers long, thousands of kilometers vast and also as much as 8 kilometers deep, this is ideal appear from room. If you were fortunate adequate to base on one edge, the contrary edge would certainly be method past the perspective.

It was possibly started by fracturing when a surrounding volcanic area (called Tharsis) started to protrude upwards, however was broadened and also grown by a collection of disastrous floodings that culminated greater than 3 billion years back.

Venus’ fold hills

We are mosting likely to discover a great deal even more concerning Venus in the 2030s when 2 Nasa goals and also one from Esa (European Space Agency) show up. Venus is almost the very same dimension, mass and also thickness as the Planet, triggering rock hounds to puzzle over why it does not have Earth-style plate tectonics and also why (or undoubtedly whether) it has fairly little energetic volcanism. Exactly how does the world obtain its warm out?

I discover it assuring that a minimum of some facets of Venus’ geology appearance acquainted. For instance, the north margin of the highlands called Ovda Regio looks noticeably comparable, aside from the absence of rivers puncturing the worn down, fold up-like pattern, to “fold hills” in the world such as the Appalachians, which are the outcome of a collision between continents.

The five most impressive geological structures in the solar system
Valles Marineris seen in a colour-coded topographic consider as if from 5,000 kilometres over the surface area (left), and also imaged by the High Resolution Stereo Video camera on Esa’s Mars Express (best). Credit Report: Google Planet and also NASA/USGS/ESA/DLR/FU Berlin (G. Neukum)

Blown Up Mercury

I’m ripping off a little with my following instance, due to the fact that it is both among the planetary system’s biggest influence containers and also an eruptive volcano within it. Mercury’s 1,550km diameter Caloris basin was formed by a major asteroid impact about 3.5 billion years ago, and soon after that its floor was flooded by lavas.

Some time later, a series of blasted kilometers-deep holes through the solidified lavas near the edge of the basin where the lava cap was thinnest. These sprayed volcanic ash particles out over a range of tens of kilometers. One such deposit, named Agwo Facula, surrounds the explosive vent that I have chosen as my example.

Explosive eruptions are driven by the force of expanding gas, and are a surprising find on Mercury, whose proximity to the Sun was previously expected to have starved it of such volatile substances—the heat would have made them boil off. Scientists suspect that there were in fact several explosive eruptions, possibly spaced over a prolonged timescale. This means that gas-forming volatile materials (whose composition will remain uncertain until Esa’s BepiColombo mission starts work in 2026) were repeatedly available in Mercury’s magmas.

The five most impressive geological structures in the solar system
Fold mountains in Ovda Regio, Venus. The insert is a similar view of part of the Applachians in central Pennsylvania. Credit: NASA/JPL

The tallest cliff?

In soil or vegetation-rich regions on Earth, cliffs offer the largest exposures of clean rock. Although dangerous to approach, they reveal an uninterrupted cross-section of rock and can be great for fossil hunting. Because geologists love them so much, I give you the seven kilometers-high Verona Rupes. This is a feature on Uranus’s small moon Miranda that is often described as “the tallest cliff in the solar system,” including on a recent Nasa website. This even goes so far as to remark that if you were careless enough to take a tumble off the top, it would take you 12 minutes to fall to the bottom.

This is nonsense, because Verona Rupes is nowhere near vertical. The only images we have of it are from Voyager 2, captured during its 1986 fly by of Uranus. It is undeniably impressive, being almost certainly a geological fault where one block of Miranda’s icy crust (the outermost “shell” of the planet) has moved downwards against the adjacent block.

However, the obliqueness of the view is deceptive, making it impossible to be sure of the face’s steepness—it probably slopes at less than 45 degrees. If you stumbled at the top, I doubt you’d even slide to the bottom. The face appears to be very smooth in the best, but rather low resolution image that we have, but at Miranda’s -170°C daytime temperature, water-ice has a high friction and is not slippery at all.

  • The five most impressive geological structures in the solar system
    Right: most of Mercury’s Caloris basin, its floor covered by dull, orange lava. Brighter orange patches are remnants of explosive eruptions. Lower left: close-up inside the red box of an explosive volcanic deposit. Upper left: details of the vent interior. Credit: NASA/JHUAPL/CIW
  • The five most impressive geological structures in the solar system
    Verona Rupes, about 50km long and several kilometres high, but not actually so cliff-like as it appears as seen by Voyager 2 during its 1986 flyby. Credit: NASA/JPL
  • The five most impressive geological structures in the solar system
    Left: Part of Titan’s Ligeia Mare, showing a coastline with valleys drowned by a sea of liquid methane. Right: The Musandam peninsula, Arabia, where coastal valleys are similarly drowned, but by a saltwater sea. Credit: NASA/JPL-Caltech/ASI/Cornell and also Expedition 63, International Space Station (ISS)

Titan’s drowned coastline

For my final example I could happily have chosen virtually anywhere on Pluto, but instead I have opted for a hauntingly Earth-like coastline on Saturn’s largest moon, Titan. Here, a large depression in Titan’s water-ice “bedrock” hosts a sea of liquid methane named Ligeia Mare.

Valleys carved by methane rivers draining into the sea have evidently become swamped as the sea level rose. This complexly indented coastline reminds me strongly of Oman’s Musandam peninsula, on the south side of the Straits of Hormuz. There, the local crust has been warped downwards because of the ongoing collision between Arabian and also the Asian mainlands. Has something similar happened on Titan? We don’t know yet, but the way that the coastal geomorphology changes around Ligeia Mare suggests to me that its drowned valleys are more than a straightforward result of rising liquid levels.

Rock and liquid water on Earth, frigid water-ice and liquid methane on Titan—it makes little difference. Their mutual interactions are the same, and so we see geology repeating itself on different worlds.


Evidence for volcanic craters on Saturn’s moon Titan


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