Stem Formation From Geyser Action
A look at the geyser and the terrain around it
Now we can look for the geyser itself, which was first photographed in Sol 162. I have assembled some color images of the area from the panoramic data and also put together a rough path of the flow of water as it occurs during an eruption in Endurance Crater. Images from numerous sols, notably 162 and 164, are used on this page.
A brief color calibration before the main event
| I took the time to
assemble the color calibration target image before assembling the rest of
the images for this page. It shows the true color of the ground and
its features so that we can get firmly fixed in our minds what it is we
would really see if we were present on the surface.
As I have mentioned repeatedly (to everyone's great weariness) in the past, the ground features are actually much darker, but it is often best to leave the color less intense and the brightness substantially higher so that we can see the details more easily. With that convenient fiction in mind, let's proceed to the main material of this page. The original images for this color calibration are here at the NASA/JPL website. |
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The Martian tides, and spouting water wearing at the rocks
The sorts of sedimentary rocks we see in Meridiani Planum are often made in the following manner. At the floor of a shallow lake or sea, where there is little movement of the water, silt and sediments settle over time. As the seasons change, the character of the material also changes- some layers are more sandy, others more clay-like. These changes can even occur over the course of a day, since the changes in wind and temperature will alter what sorts of materials are lifted by the winds.
Mars, counter to common belief, had tides just as the Earth has tides, but for a different reason. While our Moon drives our tides on a daily and monthly basis, the Sun also has a very significant influence as well. Typically, the Sun exerts roughly half the tidal force on the Earth that the Moon does; the "spring tides" and "neap tides" result when the two forces work together or in opposition.
Mars also experiences solar tides, but of a fraction of the strength of the solar tide we feel on Earth. In other words, Mars' daily tidal cycle would have been highest at local noon and midnight, and they would have been perhaps 21% as strong as the lunar tides are here. (Later numbers I have done show them to be much weaker; about 14%. Tidal force varies as the inverse cube, not like gravitation, which varies as the inverse square.)
So the layering in the sedimentary rocks is no surprise to anyone who understands astrophysics- it is just a part of reality that literally any habitable planet orbiting a star will have tides, whether it has a moon or not. Apologies to Larry Niven, who wrote a particular story (Neutron Star) in which that bit of information was crucial to a part of the plot. It won't have worked as he expected.
| Now, water spouting at
these sedimentary rocks can not only wet them, but also distort them-
since they are likely to contain some amount of clay in their makeup, a
constant force on them when they are wet should cause them to deform in a
predictable manner.
And if we look at this image to the right, we can see exactly that- the spray from the geyser has "blasted" the sediments into a curved, arcing shape. There are two distinct areas of curved or blasted clay in the center of this image. There is also a clear set of clay "fins" to the far right. The original image is here at the NASA/JPL website. |
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In this cross-eyed stereo view from Sol 164, you can see the deformed clay-containing sediments that the geyser action has shaped. Much of this area is eroded and sculpted by the action of high-speed water spray from geysers. Click the image for a full-sized view. The original images are here at the NASA/JPL website.
| A color image of the area
from Sol 162 shows other clay fins and water wash areas. This one is
very interesting because it shows a "high water" line in the
fossil spherules.
Here is a color thumbnail. Click it for a full sized image. I left the color a little too saturated in this image to help to distinguish the various features. But another fascinating feature emerges right away. See the blocky stones at the far upper right? They show the thin wafers of clay lining them, and absolutely flat faces and edges. Don't make the mistake of assuming that these are artificial- they are not. Nature has fractured the stone, and water has shaped the clay fins along the edges. These stones are absolutely identical to those found in Gusev near the "pot of gold" rock. And, it clearly implies that they have the same composition, and that geysers are (or were) active there as well. Mars must have an extensive water table. |
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Finally, I assembled a number of image frames from Sol 164 to create a large mosaic image. This image is a bit large and clumsy, but it shows where the geyser must be. It also shows that the slope of the crater wall must be roughly 20 to 25 degrees. Click here for the large mosaic.
Still wet soil from an eruption only minutes before
Now, when reviewing some of the geyser activity from Sol 146, I came across a beautiful image that had full color data and showed a geyser that had spouted minutes before- because there is still water on the soil. You can see the dark trails and droplets in the sand and where it is shielded under some spherules and shadows. This image had full spectrum data, so I was able to create my synthetic green frame and create a full color stereo image of it.
This is a cross-eyed stereo view. The right image is from left panoramic camera using filters L4, L5, and L7. The left image is from the right panoramic camera and uses filters L1 and L2, plus my synthetic green frame created from both. The color is not exact, but close enough. The raw image data is here at the NASA/JPL website, and uses frames 36, 37, 39, 40, and 41.
Look at the center of the dark soil- there is a darker streak of wet soil and a trail of droplets. Under the lone spherule just in front of the sharp rock, you can see the soil is wet still because in the shadow, the sun has not heated it as much and water has yet to evaporate. The area under the sharp fin of the rock is also still wet, as evidenced by the darker soil in a wedge pattern under it. To the far left, two streams of darker wet soil can be seen.
In closing, there are many geysers on Mars- too numerous to count- but we can see how they spray and create erosion, runoff channels, and mud. They are also responsible for the formation of the blueberry "stems" and the "rotten" rocks with very flat, angular faces, as well as the mysterious wafer-thin clay walls.