Mountains of Io can be divided into five general morphologic types:
MESA
Elevated plain with a relativelyt
smooth (at a scale of ~1 km), flat-topped surface.
Type example: Ethiopia Planim
Mesas may be difficult to distinguish
from eroded layered plains, which are not included in this database.
PLATEAU
Elevates plainwith a rugged surface
but without a steep or prominent peak.
Type example: Iopolis Planum
Pateaus are the most common morphologic
type, making up ~50% of all mountains.
PEAK
Isolated promontory with a relatively
simple morphologz rising to a sharp point or a short ridge.
Type example: Western Hi'iaka Montes
Peaks may be asymmetric in shape
and are always less than 100 (an usually less than 50) km across. Some
peaks could be the partially buried tops of once larger structures.
RIDGE
Elevated structure dominated by
one or more prominent linear or arcurate rises.
Type examples: Zaal Montes or Ionian
Mons
Ridges are often asymmentric and
can have planar flanks. The second most common morphologic type, maing
up ~25% of all mountains.
MASSIF
Elevated structure with a rugged
and complex surface morphology rising to one or more peaks.
Type examples: Boösaule Montes
and Tohil Montes
They have a rugged irregular appereance
and can be asymmetric in cross section.
MIXED TYPES
At least two mountains are complex
structures featuring two or more of the above morphologies. These are classified
on their dominant morphology.
UNCLASSIFIED
Several mountains are not classified
due to low image resolution or inability to discern their morphology.
VOLCANIC MOUNTAINS
Few mountains are identified as
having primary volcanic morphologies.
Type example: unnamed at 30S 245W
Other candidate volcanic mountains
are the twoo unusual large circular mesa-like plateaus Inachus and Apis
Tholus. They could represent volcanic material extruded from the central
vents or they could represent erosional remnants of volcanic plains.