Lunar Geological Mapping
Anybody can look at a pretty picture of a planetary surface and say, "That's Mars," or, "That's the Moon." A planetary scientist can use the picture to reconstruct the history of the surface. Recognzing various landforms on spacecraft images and determining their relative ages is an important component of this class.
Landforms are identified by comparing images of them with images of known landforms. The relative ages of the various features can be determined using the "principle of superposition." Nicolas Steno, a 17th century physician, is first credited with stating this simple but powerful geological principle. He wrote that, "... at the time when the lowest stratum was being formed, none of the upper strata existed". In other words, younger formations are on top of older ones.
Procedure
In this lab we will act as planetary scientists and interpret what we
see by creating a geological map and writing a description of a selected
region of the Moon. Our materials will be the same primary data the Apollo
scientists used when they were first trying to understand the Lunar surface
and find interesting landing spots.
The photographs you will be using were taken from three different web sites:
A reader of your map should be able to understand the various surface features are in the photograph, and in what order they were formed. Often, it is not clear what a surface feature is or when it was formed. Be bold and make a guess; we are not going to go to the Moon in the near future, so it will be hard to tell if you are wrong!
The pictures below are an example of what you are to do. On the left is an image of the area surrounding Hadley Rille, the Apollo 15 landing site. On the right is a geological map of the region identifying the different landforms. On the right of this map is a legend, along with a timeline indicating the relative ages of the various features.
The photographs you will be using in class are of small regions of the Moon. They have been picked because each picture has a number of features that should be mapped. The extent to which you should include detail is limited by time -- include enough to warrant 20 points, but not so much that you get home after midnight tonight.
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| Features to identify: secondary craters, simple impact craters, complex impact craters, basin, smooth mare surface, sinuous rilles, straight rilles, ghost craters, highlands, rough terrain, lava channels, chain craters, source crater, wrinkle ridges, central peaks, rays | |
What to turn in
You need to turn in your geological map and a paragraph describing the
features you mapped. Make sure you have a key to your map that includes
the relative age of the various features.
Your paragraph should both describe the features and indicate their relative ages. For example, the following paragraph describes the above image of Hadley Rille.
The oldest features in this image are the highland mountains. A mare surface fills in much of the area between the highland regions and overlays and abuts the highlands. A lava channel (rille) cuts across the mare surface. Impact craters dot the mare surface and one large one partially covers the lava channel. This means that the craters are younger than the mare and the large crater is younger than the lava channel. The rest of the impact craters on the mare do not intersect the channel, so their relative ages cannot be determined.