University of Michigan - Department of Astronomy

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Geologic Age

Relative Geologic Age and Cross Cutting Features

Information you need to complete this is in the Introduction

Please check with your GSI about what sections to complete.


Part 1: Viking 1 image

There are two images for this section, a Viking 1 orbiter image, and a labeled copy.  Viking 1 had a television camera on board to transmit the images back to Earth.  It was able to capture some very wide views, but the resolution is rather poor: the smallest features are several hundred meters across.

The plains are the bottom most layer, so everything else is more recent.  The channel and craters should look like depressions.  If they look like they are raised, try looking at it upside down instead.

  1. Which labeled feature is topmost?

  2. Does that make it more recent, or older than the plains?

  3. Which feature does it sit directly on top of?

  4. Which is OLDER, the channel or large crater?  Explain



Now check yourself (do not change your answers to the questions above!)
The plains existed first, so they are the oldest.  The large craters were next.  They do not intersect, and they seem to have the same amount of wear or erosion, so we can’t say which one actually occurred first.  The channel cuts through both large craters, so it formed more recently.  Finally, the tiny thing labeled “small crater” is in the channel, so it is the most recent or youngest feature. 

  1. Do your answers to the above questions agree with this chronology?  If not, where did you go wrong, and how will you avoid making those mistakes in the next part?



Part 2: THEMIS image


There are two images for this section as well, an unlabeled full size image and labeled smaller version of an image from the THermal EMission Imaging System onboard the 2001 Mars Odyssey spacecraft.  Single wavelength THEMIS images are displayed in black and white, and have a resolution of 18 meters/pixel, more than 10 times more detail than the Viking orbiters.  It is copyright NASA/JPL/Arizona State University.  Again, if the crater looks like a bump, it might help to look at it upside down (this is also a smaller image)

This image shows a channel that cut through a plain and formed an island around a large crater, which is not labeled because it is fairly obvious. There are several smaller craters labeled in the labeled version. Wider field images show the plains were probably flooded at the same time as the island, so the last resurfacing of the plains probably took place around the same time as the formation of the islands.

  1. Put the other features in chronological order: the channel, large crater, island, and each of the four labeled craters. Explain how you arrived at this order.

Last modified: 2/20/08 by SAM based on activities 3 - 6 from MarsUncovered_SG_V14.pdf by NASA education

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