A
boundary between heavily cratered regions (top right) and more lightly cratered
areas (bottom right) is very similar to boundaries on the moons Dione and
Rhea, indicating a period of internal activity early in Tethys' history
that partially resurfaced the older terrain. |
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The
large crater in the upper right lies almost on the huge trench system that
girdles nearly three-fourths of the circumference of the satellite. The
trench itself is seen in this image as a linear set of markings to the lower
left of the crater. The trench, several kilometers deep, is indicative of
a cold, stiff ice crust at the time of its formation. Formation of this
trench system could have resulted from the expansion of Tethys as its warm
interior froze. |
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