geology of mars volcanic image
introduction
aeolian
cratering
hydro
landslides
tectonic
volcanic
  Discussion
The Tharsis Bulge
Shield Volcanos
Patera
Lava Plains
Identifying Plains
volcanic

How Are Lava Plains Identified?
Another sign indicating the volcanic origin of a plain is the existence of volcanic cones on the plain (Figure 6.17). In the middle of this image, there is a cone about 4 km across with an elongated caldera.

figure 6.17 figure 6.18

Small cones with a summit pit can also be found on other lava plains (Figure 6.18) . Most of the cones in this photo are about 500 m (or 1/3 mile) across. Their linear alignment may be related to the fault system of the area. Exactly how they formed is not known. Viscosity of the lava might also play a role in their formation.



Contrasts of surface smoothness can be diagnostic also (Figure 6.19) . Some experience may be required to delineate the origin of different smooth surfaces. The existence of wrinkle ridges may also be indicative because it takes a harder surface (such as the ones formed by lava flows) to buckle to produce wrinkle ridges (Figure 6.20) .

 figure 6.19 figure 6.20

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geology of mars