Jovis Tholus
Jove's Tholus lies nearly due east of Olympus Mons and northwest of
Ascreus Mons. Thus, it lies on the very northern edge of the lava plains
surrounding the Tharsis Montes. It is roughly 80 km long by 60 km wide,
and it has a large off-center caldera complex some 40 km in diameter. The
total height is probably close to 2 km. Its age is very poorly
constrained. The volcano could be anywhere from 2.3 to 3.5 billion years
old. Like most tholi, Jovis Tholus is surrounded by younger lava flows.
These lavas also cover a set of buried
graben
, however. The graben cut the
easternmost and westernmost edges of the volcano. Jovis also shows signs
of a long eruptive history. Its sprawling caldera contains no less than 5
craters. These calderas march southwest from the first, central caldera.
Each younger caldera has a lower floor. (Viking Orbiter images 41B17 &
41B19, from Plescia (1994) Icarus, vol. 111.)
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