Caption 1: "Hero Rupes is a
lobate scarp
on Mercury
≥ 300
km long located in
Mercury's
southern hemisphere.
Discovered by the
Mariner 10 spacecraft (1973--1975)
in 1974,
it was formed by a thrust fault
thought to have occurred due to the shrinkage of
Mercury's core
and mantle as
they cooled and contracted over time when
Mercury's lithosphere
had already solidified."
(Somewhat conflated and edited from
Wikipedia: Hero Rupes
and Wikipedia:
Mercury: Internal structrure).
Features:
- Lobate scarps
are common geological features of
Mercury
and also of the Moon where they
are, however, much smaller in height and much less conspicuous than
on Mercury.
- On Mercury,
the lobate scarps
are giant curved
cliffs that rise as high as
3
km and
can stretch over hundreds of kilometers
(Se-460,
HI-165).
- The cooling and contraction of the
Mercury's core
and mantle (mentioned above in the preamble)
caused crinkling or faulting on the outside of
Mercury's lithosphere
which led to the
lobate scarps.
It is thought that Mercury's
radius
decreased by a few kilometers overall
(Se-460).
-
Mercury's lithosphere
when Mercury
was still quite on hot on the inside
was probably rather thin compared to the
lunar lithosphere.
- The thicker and perhaps stronger
lunar lithosphere
probably did NOT contract so much as
Mercury's lithosphere
during the cooling phase.
However, small
lobate scarps
on the Moon show that some faulting
and contraction occurred.
The Moon's
radius may have decreased by ∼ 100 m in the
last
gigayear.
See
NASA's LRO Reveals
'Incredible Shrinking Moon', 2010 Aug19.
Until circa
2010, it seesm there
was little discussion of the
Moon's
lobate scarps
and NOT much was inferred from them.
Caption 2: A cartoon of a scenario for the
formation of Mercury's
lobate scarps
(HI-165).
But does "curved" refer to slope or the line of the
lobate scarp
on the ground?
Images:
- Credit/Permission:
NASA,
Mariner 10 spacecraft (1973--1975),
2000 (when added to an online archive:
uploaded to
Wikimedia Commons
by User:Ruslik0,
2010) /
Public domain.
Image link: Wikimedia Commons:
File:Hero Rupes.jpg.
- Credit/Permission: ©
David Jeffery,
2003 / Own work.
Image link: Itself.
Local file: local link:
mercury_lobate_scarps.html.
File: Mercury file:
mercury_lobate_scarps.html.