Planetary and Space Science 111 (2015) 144–154
Contents lists available at ScienceDirect
Planetary and Space Science
journal homepage: www.elsevier.com/locate/pss
Remnant buried ice in the equatorial regions of Mars: Morphological
indicators associated with the Arsia Mons tropical mountain glacier
deposits
Kathleen E. Scanlon a,n, James W. Head a, David R. Marchant b
a
b
Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI 02912, USA
Department of Earth & Environment, Boston University, Boston, MA 02215, USA
ar t ic l e i nf o
a b s t r a c t
Article history:
Received 30 September 2014
Received in revised form
25 March 2015
Accepted 27 March 2015
Available online 9 April 2015
The fan-shaped deposit (FSD) on the western and northwestern flanks of Arsia Mons is the remnant of
tropical mountain glaciers, deposited several tens to hundreds of millions of years ago during periods of
high spin-axis obliquity. Previous workers have argued that the Smooth Facies in the FSD contains a core
of ancient glacial ice. Here, we find evidence that additional glacial ice remains preserved within several
other landforms in the Smooth Facies and Ridged Facies. These include landforms that we interpret as
kame and kettle topography on the basis of their distribution, size, and morphologies ranging progressively from knobs to degraded knobs to pits. We argue that some moraines in the Ridged Facies are icecored on the basis of their interactions with lava flows and the axial troughs at the crests of some
moraines. We also argue that dunes with axial troughs, found in and surrounding the FSD, are the
remnants of sediment-covered snow dunes formed by reworking of snow or glacial ice, and that the axial
troughs form as tension cracks in the sediment and deepen by sublimation of the underlying ice. Longterm preservation of water ice in equatorial environments is assisted by a meters- to decameters-thick
debris cover (lag) formed from sublimation of dirty ice, as well as burial beneath volcanic tephra and
aeolian deposits. This ancient ice could contain preserved biosignatures, provide information on Martian
climate and atmospheric history, and serve as a resource for human exploration.
& 2015 Elsevier Ltd. All rights reserved.
Keywords:
Mars
Mars surface
Mars climate
1. Introduction
The western and northwestern flanks of the equatorial Tharsis
Montes volcanoes were covered by cold based mountain glaciers as
recently as 125–220 million years ago (Kadish et al., 2014), as evidenced by the morphology, stratigraphic relationships, and spatial
distribution of landforms in the fan-shaped deposits (FSDs) on each
volcano (Williams, 1978; Lucchitta, 1981; Head and Marchant, 2003;
Shean et al., 2005, 2007; Kadish et al., 2008a; Scanlon et al., 2014,
2015). This geomorphologic evidence is bolstered by climate and
glacial flow models that predict snow accumulation and ice flow in
those regions during periods of high spin-axis obliquity (Forget
et al., 2006; Fastook et al., 2008). Following a return to lower
obliquity and the resulting change in climate conditions, the glacial
ice ablated and returned to higher latitudes and the poles (Head
et al., 2003, 2006a, b), leaving the Tharsis Montes fan-shaped
deposits. A major question is whether buried ice still remains in
n
Corresponding author. Tel.: þ 1 401 863 3485; fax: þ 1 401 863 3978.
E-mail address: kathleen_scanlon@brown.edu (K.E. Scanlon).
http://dx.doi.org/10.1016/j.pss.2015.03.024
0032-0633/& 2015 Elsevier Ltd. All rights reserved.
some of these deposits, despite the peak insolation and relatively
high temperatures expected at equatorial latitudes now and in the
recent past (e.g. Mellon and Jakosky, 1993, 1995; Mellon et al.,1997).
Morphological evidence for buried present-day water ice in the
tropics and mid-latitudes of Mars can be generally divided into
three categories, as follows:
(1) Surface textures attributed to partial removal of ice. These
include sublimation pits or hollows (e.g. Mustard et al., 2001;
Mangold, 2003; Kadish et al., 2008b), scalloped depressions
(e.g. Lefort et al., 2010; Séjourné et al., 2011), sublimation
polygons and “brain terrain” (e.g. Levy et al., 2008, 2009), and
other dissected terrains such as “basketball texture” (e.g. Head
et al., 2003) or “ridge and valley texture” (Pierce and Crown,
2003; Chuang and Crown, 2005).
(2) Topographic profile. Lobate debris aprons (LDA), lineated valley fill (LVF), and concentric crater fill (CCF) on Mars have been
interpreted as debris-covered glaciers with remnant ice cores,
partially on the basis of the glacier-like convex upward topographic profiles at their margins (e.g. Mangold and Allemand,
K.E. Scanlon et al. / Planetary and Space Science 111 (2015) 144–154
2001; Holt et al., 2008; Head et al., 2010; Levy et al., 2010).
(3) Unusual crater morphologies. “Ring-mold” craters (Kress and
Head, 2008) have been interpreted as resulting from impacts
into buried ice on the basis of their size-frequency distribution,
which is consistent with smaller impacts not penetrating far
enough to reach the buried ice; their annular moats, which are
a characteristic feature of experimental impacts into ice-rich
substrates; and the apparent degradation sequence represented
by the range of ring-mold crater morphologies (Pedersen and
Head, 2010). Pedestal craters, perched craters and excess ejecta
craters (e.g. Kadish and Head, 2011) are interpreted to form by
impacts into an ice-rich substrate, where either the impact
process itself (in the case of pedestal craters) or the excavation
of rocky material from underneath the ice-rich layer (in the case
of perched and excess ejecta craters) creates a surface deposit
that protects the ice-rich material immediately surrounding the
crater against sublimation.
145
3. Landforms interpreted to be indicative of remnant ice
On Earth, remnant patches of buried glacier ice may occur
wherever overlying debris is sufficiently thick to retard ice ablation.
Examples include ice-cored moraines, detached blocks of ice buried
beneath proglacial sediment, and remnant, stagnant ice buried
beneath thick sublimation till (e.g. Hambrey, 1984; Marchant et al.,
2002; Evans, 2009; Swanger et al., 2010; Irvine-Fynn et al., 2011;
Lacelle et al., 2011; Monnier et al., 2008).
In the coldest and driest region of the Mars-like Antarctic Dry
Valleys, 40Ar/39Ar ages of volcanic ash deposits indicate that
underlying remnant glacier ice has been preserved for millions of
years (Sugden et al., 1995; Marchant et al., 2002; Kowalewski et al.,
2006, 2012). We propose that the morphology of several landforms adjacent to Arsia Mons suggests that ice millions of years
old is also present in the Arsia Mons FSD.
3.1. Pit-and-knob terrain
Remnant ice at equatorial latitudes on Mars is of potential
interest as an exploration target for several reasons. Gas bubbles
preserved in terrestrial ancient ice can be used to develop time
series for the molecular and isotopic composition of the atmosphere (e.g. Alley, 2000; Lüthi et al., 2008; Kobashi et al., 2011;
Capron et al., 2012; Bazin et al., 2013; Rhodes et al., 2013). If a
reliable chronology and isotopic baseline could be developed for
Mars, then these data would be particularly useful, as they could
potentially help constrain orbital parameter variations prior to
those that can be calculated a priori (Laskar et al., 2004). The Arsia
Mons FSD has been suggested as a well-suited target for future
human missions (e.g. Levine et al., 2010), and ice deposits within
the FSD would offer a potential water and fuel resource for human
exploration (e.g. Sridhar et al., 2004).
At 166,000 km2 in area, the Arsia Mons FSD (Head and
Marchant, 2003; Shean et al., 2005, 2007; Scanlon et al., 2014,
2015) is the largest of the Tharsis Montes FSDs (Fig. 1). Crater
counts indicate that the FSD has been in place for 210 Ma
(Kadish et al., 2014). The Smooth Facies, one of the geomorphologic units in the FSDs (Zimbelman and Edgett, 1992; Scott and
Zimbelman, 1995), has been interpreted as remnant alpine-like
debris-covered glaciers (Head and Marchant, 2003). Likewise,
Shean et al. (2007) suggest that lineated debris displaying concentric ridges and partially filling tectonic graben higher up the
volcanic edifice is also cored by glacier ice. The convex topography
of these deposits (Shean et al., 2007), as well as the morphologic
indicators of active flow (Head and Marchant, 2003; Marchant and
Head, 2007) and the unique morphology of superimposed craters
(Head and Weiss, 2014), suggest that buried ice 100–300 m thick
may still be present at depth. In this contribution, we expand the
search for buried ice and review several other classes of landforms
in the FSD that have not been previously described, and whose
morphology indicates that remnant ice may still be present.
2. Data and methods
Images in this study are from the Mars Reconnaissance Orbiter
(MRO) Context Camera (CTX), with 5 m per pixel resolution (Malin
et al., 2007), augmented with images from the High Resolution
Stereo Camera (HRSC) at 10–30 m per pixel resolution (Neukum and
Jaumann, 2004). Topographic data is from the Mars Orbital Laser
Altimeter (MOLA) at 463 m per pixel resolution (Zuber et al., 1992;
Smith et al., 1999) and, where available, HRSC-derived Digital Elevation Maps (DEMs) with 100 m per pixel resolution (Dumke
et al., 2008). Contour maps were created using the Spatial Analyst
toolkit in ArcMap 10.0.
Near the northern edge of the FSD is a field of mounds
(“knobs”) and shallow topographic depressions (“pits”; Figs. 1 and
2). Each knob is up to 1 km in diameter. Interspersed among the
knobs are pits of similar size and shape to the knobs (Figs. 2 and
3). The pits and knobs are generally aligned, and the lines on
which they fall are concentric with the outline of the Smooth
Facies (Figs. 1 and 2) and with drop moraines left by a relatively
young debris-covered glacier extending from a nearby graben
(Shean et al., 2007). Many of the smaller knobs are surrounded by
shallow annular depressions (“moats”), and some pits have what
appear to be degraded knobs at their centers (Fig. 3). We propose
that the pit-and-knob terrain is ice-cored and that the landforms
represent a progression in which gradual loss of ice via sublimation causes topographic inversion, with knobs becoming moated
knobs, then pits with degraded knobs, and finally pits (Fig. 4).
In terrestrial zones of rapid ice retreat, blocks of ice detached
from the retreating edge of a glacier may become partially buried
beneath glacial outwash (Thwaites, 1926; Price, 1969; Fay, 2002;
Russell et al., 2010; Evans, 2011; Knight, 2012). When the blocks
eventually melt, they leave “kettle holes” where the blocks formerly stood. Fields of pits interpreted as kettle holes have been
observed on Mars in the circumpolar Dorsa Argentea Formation
(Dickson and Head, 2006). The morphological evidence suggests
that the Arsia FSD pit-and-knob terrain may have resulted from
backwasting of ice in the Smooth Facies and subsequent burial of
the isolated ice blocks, analogous to the formation of terrestrial
kettled outwash plains (Fig. 5). This evidence comprises (1) the
similarity in size and shape between the pits and knobs, (2) the
genetic relationship implied by the presence of knobs with moats,
and (3) the co-alignment of the pits and knobs with the outline of
the Smooth Facies and with lineations in the Smooth Facies
(Fig. 6). Because of the cold Amazonian climate, however, the ice
blocks would have sublimed rather than melted to leave the pits
behind, and the sediment that embayed them would have been
volcanic tephra, englacial debris, or aeolian sediment, rather than
glacial outwash as in terrestrial kettled plains. The concentric
fractures surrounding many of the pits (Fig. 3) suggest that nearsurface sediment, possibly cemented by pore ice, moved downslope toward pit centers as underlying ice sublimed; similar patterns can be observed on Earth where the removal of blocks of
buried ice causes concentric fractures to form in the overlying
sediment (Sanford, 1959; Dickson and Head, 2006). This sediment
cover could have armored some of the ice blocks against further
sublimation, leaving the present-day knobs.
Alternatively, the pit-and-knob terrain may have formed in a
manner analogous to terrestrial “controlled moraine” (e.g. Evans,
2009; Szuman and Kasprzak, 2010; Bennett and Evans, 2012; Lakeman
146
K.E. Scanlon et al. / Planetary and Space Science 111 (2015) 144–154
Fig. 1. Geomorphological unit map of the Arsia Mons fan-shaped deposit (FSD), after Zimbelman and Edgett (1992) and Scott and Zimbelman (1995); reproduced from Scanlon
et al. (2014) and annotated. Red lines denote large volcanic graben, white lines denote contacts between units, and black lines denote the outlines of glaciovolcanic landforms
(Scanlon et al., 2014) and landforms characteristic of volcanism-induced wet-based glacial conditions (Scanlon et al., 2015). Closed and open green circles in the Smooth Facies
denote pits and knobs, respectively. The regions where moraines and dunes with linear troughs (Sections 3.2 and 4, respectively) are located are marked by shaded black and
white ellipses, respectively. The area shown in Fig. 2 is denoted by a white box. THEMIS 100 m/pixel daytime image mosaic. This and all other images in this paper are oriented
with north toward the top of the image. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
glacier retreats. Incomplete loss of this dead ice results in linear
arrangements of mounds and kettle holes, with the continuity and
linearity of the mounds breaking down as the removal of ice continues
to completion. As with the “backwasting” formation model, the knobto-pit progression (Fig. 4), the linearity of the remaining knobs
(Figs. 1, 2 and 6), and the concentric fractures surrounding pits (Fig. 3)
suggest that these features had ice cores at formation and that the
removal of ice from these features has not proceeded to completion.
This “controlled moraine” model (Fig. 7) accounts for the linear
arrangement of the pits and knobs without requiring widespread
accumulation of ice blocks to have occurred at the ice margins. We
therefore favor this model of pit-and-knob terrain development.
3.2. Drop moraines with linear troughs
Fig. 2. Pit (white arrow) and knob (black arrow) terrain in the Arsia Mons fanshaped deposit (see Fig. 1 for location). Pits and knobs form lines concentric to the
border of the Smooth Facies. The area shown in Fig. 3 is denoted by a white box.
Some knobs appear to be surrounded by moats (red arrow), implying a progression
from knob to pit (see also Fig. 4). CTX image P08_004056_1741_XI_05S125W. (For
interpretation of the references to color in this figure legend, the reader is referred
to the web version of this article.)
and England, 2012). When variable concentrations of debris within or
on top of glaciers (e.g. Mackay et al., 2014) are shaped into belts by
glacial flow, bands of debris can isolate patches of stagnant ice as the
At the northwestern edge of the deposit, some of the drop
moraines (Head and Marchant, 2003) in the Ridged Facies have
linear troughs along their crests (Fig. 8). These moraines are
typically 100 m wide, and some are continuous for over 100 km.
Other nearby moraines have similar dimensions but lack the
characteristic crest troughs. We interpret these moraines to have
developed their trough morphology by the loss of ice via sublimation. In terrestrial settings, ice-cored moraines can develop at
the margins of glaciers when bands of debris within a glacier
isolate small masses of ice from the main body of ice as the glacier
retreats (e.g. Evans, 2009).
The hypothesis that moraines in the FSD may contain remnant
ice is also supported by the lone subaerial lava flow in the Ridged
Facies, which has a chaotic texture interpreted to have resulted
K.E. Scanlon et al. / Planetary and Space Science 111 (2015) 144–154
from interactions between the lava flows and ice in and around
the moraines at the time of flow emplacement (Scanlon et al.,
2014). If ice was present in the moraines when lava flowed over
them, the lava would be expected to interact with it by melting
and collapse (e.g. Edwards et al., 2012), as well as explosively (e.g.
Belousov et al., 2011), imparting a chaotic texture to the flows.
4. Postglacial ice-related landforms
Dispersed throughout the northwestern edge and surroundings
of the Arsia FSD are relatively short ( 2 km, but some as much as
147
9 km) elongate ridges with axial troughs (Fig. 11). The width of the
ridges in any one population of ridges is highly uniform, but
typical widths vary between regions from 100 m to 350 m.
Their distribution is not restricted to any underlying unit of the
FSD, and they often appear superposed on and draping the contacts and features of the underlying FSD units (Fig. 10). In contrast
to the characteristics of the concentric drop moraines of the
Ridged Facies, they are consistently oriented southwest-to-northeast wherever they occur, and they are straight rather than curved
in plan view. They are also continuous over much shorter distances than the drop moraines with linear troughs. They are often
Fig. 3. Pit-and-knob terrain: (a) Closeup view of pits and knobs outlined by the white box in Fig. 2. CTX image P08_004056_1741_XI_05S125W. (b) Sketch map of area in
Fig. 3a; pits are shown in red, knobs in yellow, and fractures in blue. (For interpretation of the references to color in this figure legend, the reader is referred to the web
version of this article.)
Fig. 4. Examples of knobs (a), moated knobs (b), pits with remnant knobs (c), and pits (d), from CTX images P08_004056_1741_XI_05S125W and
P16_007392_1743_XN_05S126W.
148
K.E. Scanlon et al. / Planetary and Space Science 111 (2015) 144–154
Fig. 5. Comparison of kettle hole formation process on Earth (right) and a “backwasting” model of pit and knob terrain formation in the Arsia Mons fan-shaped deposit (left).
As a glacier (a) recedes, blocks of ice separate from its terminus (b). In a warm-based, terrestrial glacier, outwash from the receding glacier will partially bury (or in some
cases, not shown, completely bury) these blocks; on Amazonian Mars, atmospheric dust or volcanic tephra covers the ice blocks before they fully sublime (c). When the ice
fully melts or sublimes, shallow pits are left behind in the sediment; in the case of Mars, some ice has been armored by debris fall and remains as debris-covered knobs (d).
Fig. 6. Pits and knobs fall along lines concentric to the boundaries of the Smooth Facies. (a) THEMIS image mosaic. (b) Sketch map; the Smooth Facies is shown in orange, the
Knobby Facies in blue, pits as filled green circles, and knobs as open green circles. (For interpretation of the references to color in this figure legend, the reader is referred to
the web version of this article.)
K.E. Scanlon et al. / Planetary and Space Science 111 (2015) 144–154
concentrated in local topographic lows rather than being uniformly located within a particular unit. In general, they appear
dune-like in nature, but are distinguished from typical dune forms
in having a trough along their long axis.
On the basis of the physical proximity of these features to the
Arsia Mons glacier deposits, and the likelihood that at least some
snow and ice is deposited in the Tharsis FSD regions whenever
spin-axis obliquities measurably increase from current values
(Forget et al., 2006; Schon, Head, 2012), we suggest that this
morphology results from the sublimation of ice along the crests of
ice-rich dunes. Pedestal craters found throughout the Tharsis
region and dated to 12–13 Ma (Schon and Head, 2012) suggest that
149
several meters of ice covered the Tharsis region in a recent phase
of moderately high obliquity. Due to the superposition of the
dunes upon the other units of the Arsia Mons FSD, we propose that
deposits such as this later ice cover may have been the source of
the ice that formed the dunes displaying linear troughs. The
greater density of dunes within the FSD (Fig. 10) suggests that the
dunes may also have been built by reworking of the ice and debris
from the FSD itself.
The morphology of these ridges suggests the removal of a
volatile component. There are two possibilities for the nature of
the dust-ice mixture that could give rise to the troughs at the crest
of the ridges. First (Fig. 11a), the ridges could have formed as
Fig. 7. A “controlled moraine” model of pit-and-knob terrain formation in the Arsia Mons fan-shaped deposit. (a) Glacial flow concentrates debris into discrete bands within
a debris-covered glacier (or thickens bands of debris atop the glacier, resulting in similar variable preservation of the underlying ice). (b) As downwasting occurs, the bands of
debris isolate masses of ice, concentric to the outlines of the glacier. (c) As ice removal proceeds, the ice-cored ridges become less continuous and form knobs or elongate
mounds. Complete removal of ice in some mounds (by sublimation) results in the formation of collapse pits.
Fig. 8. Candidate ice-cored moraines. (a) Some moraines in the Ridged Facies near the Northwest Plateau (Scanlon et al., 2014; see Fig. 1) have troughs along their crests. CTX
image mosaic. (b) Close view of the drop moraine with linear trough, highlighted by two arrows in Fig. 8a. CTX image P17_007814_1773_XI_02S129W.
150
K.E. Scanlon et al. / Planetary and Space Science 111 (2015) 144–154
mixed snow-ice dunes formed during snow deposition at higher
obliquity. When the spin-axis obliquity lowered such that ice was
no longer stable at the equator (e.g. Jakosky and Carr, 1985; Mellon
and Jakosky, 1993), the snow component would have sublimed
and the dust component would have become concentrated in the
outermost layers (Fig. 11b), analogous to the development process
of the martian latitude-dependent mantle and some types of terrestrial loess (Mustard et al., 2001; Head et al., 2003).
If the sides of the dunes were sufficiently steep, these dry outer
layers would have slumped down the ridge sides, forming debrisrich piles at either side of the crest and exposing more ice to
sublimation (Fig. 11c). A similar process helps drive topographic
inversion cycles in ice-cored moraines and creates ring-shaped
“circular moraine features” from sufficiently tall debris-covered
dead ice blocks on Earth (Ebert and Kleman, 2004). In concert with
this mechanism, continued wind shear could cause dust to be
removed from the crest, exposing buried ice-rich material to
preferential sublimation.
Second, the ridges could have formed as snow dunes that were
later covered by a layer of dust or tephra (Fig. 12a and b). Because
the least compressive stress in a topographic ridge is oriented
horizontally away from the axis of the ridge (Fiske and Jackson,
1972; McTigue and Mei, 1981; Dieterich, 1988; Rubin and Rubin,
2013), long tensile cracks aligned with the dune crests could be
expected to form in the sediment cover (Fig. 12c). This tendency
could be further enhanced if the surface sediment layer was not
frozen to the underlying snow and ice, in which case it could
slump to either side of the ridge crest. Fractures are observed
along the crests of debris-covered snow ripples in the Antarctic
Dry Valleys (compare Figs. 9 and 13) and develop parallel to
topographic contours on niveo-aeolian dunes and beds in Alaska
as their snow component melts (Koster and Dijkmans, 1988).
These fractures in the protective dust cover would enhance sublimation directly beneath them by exposing the underlying snow
(Mangold, 2003; 2011), eventually leaving a hollow along the ridge
axis (Fig. 12d and e). On the basis of the similarity of these features
to terrestrial debris-covered snow dunes, and the fact that plausible heights for the ripples are lower than the ice block heights
that form ring-shaped circular moraines on Earth (and are thus
more likely to create a single ridge of debris than two parallel
ridges; Ebert and Kleman, 2004), we currently favor this latter
interpretation. High-resolution topographic data will help distinguish between these mechanisms more conclusively by constraining the height and side slopes of individual ridges.
Unlike the drop moraines described in Section 3, there are no
dunes in the FSD that are similar in shape, size, and distribution to
the crest-trough dunes but which lack the troughs. This suggests
Fig. 9. Typical dunes with linear troughs, found throughout the western extent of
the Arsia Mons fan-shaped deposit. CTX image P19_008605_1772_XI_02S129W.
that ice removal in the dunes may have proceeded to completion.
By analogy with the Antarctic debris-covered snow ripples, ice
may still be present beneath the dunes, but this cannot be determined from image data alone. The primary importance of these
landforms is therefore not as a likely reservoir of present-day ice,
but rather as an additional indicator of the extent and aeolian
transport of equatorial ice in a recent high-obliquity excursion.
5. Discussion
How much ice remains within the FSDs, what data aside from
geomorphologic observations indicate the presence of this ice, and
where does this remnant ice fit in the timeline of Amazonian climate change? For comparison, the best-studied deposits of nonpolar Amazonian ice are the Lobate Debris Aprons (LDAs), which
are mid- to late-Amazonian aged debris-covered remnant glaciers
found throughout the mid-latitudes of Mars (e.g. Head et al.,
2010). Radar data is consistent with the hypothesis that LDAs are
composed of massive water ice covered by a layer of debris 0.5–
10 m thick (Holt et al., 2008; Plaut et al., 2009). If the age of the
FSD and the LDAs are similar, and the temperature and humidity of
the environments surrounding them (and hence the stability of ice
in those environments) are also similar, then the depth to massive
ice would be expected to be somewhat greater for landforms in
the equatorial FSDs than for the mid-latitude LDAs (e.g. Schorghofer and Forget, 2012). Many of our proposed ice-cored features
at Arsia Mons are several times greater than 10 m in height, such
that a debris cover thick enough to preserve an ice core could
remain. The fact that the characteristic crest troughs are most
evident in the relatively small moraines and dunes may in fact be
due to their smaller size; the debris cover on larger features may
be sufficient that no significant volume of ice has yet been
removed, or that the thick surface debris masks topography
associated with underlying ice loss.
The elevated concentration of hydrogen on the western sides of
Arsia and Pavonis Mons relative to their eastern sides (as indicated
by local minima in epithermal neutron fluxes; Boynton et al.,
2002; Elphic et al., 2005) is also consistent with the hypothesis
that some ice remains in the FSDs. Elphic et al. (2005), making the
simplifying assumption that the hypothesized ice-rich deposits are
pure ice overlain by dry sublimation till in order to obtain a first
order estimate, calculated that ice could lie 60 cm below the
surface. Since the widespread dunes in the FSD suggest recent or
ongoing aeolian activity, it is possible that wind has removed
debris from the deposit such that the thickness of debris currently
overlying any ice in the deposit is less than the amount that was
required to preserve it to the present day.
Radar data could potentially bolster the geomorphological
evidence for remnant ice in the FSDs, but have not been clear. For
example, it has also been suggested that the Pavonis Mons FSD
contains remnant ice in its Smooth Facies deposits (Shean et al.,
2005). Recent SHARAD radar profiles, however, did not detect
strong reflections in this unit as they did for the LDAs, and as
would be expected for an internally layered ice core (Campbell
et al., 2013). Head and Weiss (2014) presented geomorphologic
evidence for up to several hundred meters of present-day ice
under a Z16 m thick debris cover in the Smooth Facies at Pavonis
and Arsia Mons. They suggest that the lack of strong radar
reflections could be explained if any ice in the Smooth Facies is
intermingled with volcanic tephra. Due to the proximity of the
Arsia Mons volcano, tephra would be expected to be more abundant in the FSD than in the LDAs.
The total amount of ice potentially remaining in the landforms
described in this paper cannot be estimated at present due to the
absence of topographic data that can resolve the smaller classes of
K.E. Scanlon et al. / Planetary and Space Science 111 (2015) 144–154
potentially ice-cored landforms, e.g. Ridged Facies moraines. The
scale of the kettle pits and hypothesized ice-cored knobs (Section
3.1) is larger, however, and these landforms are resolved in HRSC
DEMs (Fig. 14). Within the area of HRSC DEM coverage, knobs
stand 15–80 m high, whereas pits are typically 5–10 m deep. If
this height difference is entirely caused by the removal of volatiles,
and if these dimensions are typical for the pits and knobs not
covered by HRSC DEMs, the hundreds of knobs remaining in the
FSD could each contain a body of ice 20–90 m thick at their cores.
6. Conclusions
The geomorphology of three classes of landform in the Arsia
Mons FSD suggests that the deposit contains more remnant ice
than previously thought. Evidence for extant ice in the bulk of the
Smooth Facies has been described by previous researchers (Shean
et al., 2007; Head and Weiss, 2014); the evidence we present for
extant ice in some Ridged Facies drop moraines and in small
151
landforms at the margins of the Smooth Facies increases the total
volume of proposed ice in the FSD. Trough morphologies suggest
that ice has been removed from some but not all of the glacial
moraines in the deposit, and the chaotic surface texture of volcanic
flows to the northwest of the deposit suggests that they interacted
with ice-cored moraines. The size and morphology of pits and
knobs near the northern edge of the FSD suggest that the knobs
contain ice that is armored by debris. These deposits should be
added to the volumes of sequestered ice mapped throughout the
mid-latitudes (Levy et al., 2014). Fields of dunes with linear
troughs along their crests suggest that windblown snow was
widespread across the region in the Amazonian.
The knobs and moraines examined in this study represent a
potential reservoir of buried, present-day equatorial ice, in addition to the ice previously estimated (Shean et al., 2007; Head and
Weiss, 2014) to remain in the Smooth Facies. These features are
present in several regions of the deposit, near other landforms of
climatological, volcanological, and possible astrobiological interest
(Scanlon et al., 2014, 2015). Because of its location near the
Fig. 10. The majority of the ridges with linear troughs, here interpreted as dunes, are oriented southwest-to-northeast wherever they occur, and are concentrated in local
topographic lows rather than being associated with a specific stratigraphic level in the deposit. (a) CTX image mosaic. (b) CTX mosaic with dunes highlighted in red, drop
moraines highlighted in blue, and white arrows indicating locations where dunes are concentrated in the local topographic lows between lava flows. (For interpretation of
the references to color in this figure legend, the reader is referred to the web version of this article.)
Fig. 11. The dunes with linear troughs may have formed from dust-ice dunes (a). Upon a change from the climate in which they formed, ice would sublime from the surface
of the dunes (b). Over time, this dry material would slump down the dune sides, exposing fresh ice-cemented material at the dune center (c) to continuing sublimation (d).
152
K.E. Scanlon et al. / Planetary and Space Science 111 (2015) 144–154
Fig. 12. The dunes with linear troughs may have formed from snow dunes (a) that gained a dust cover (b), e.g. from a pyroclastic eruption. Such a cover would slump away
from the dune crest over time (c), forming cracks at the crest and exposing the snow beneath to sublimation (d). As the snow sublimed, dust would fall in to fill the space left
behind (e).
Fig. 13. Dust- and sand-covered ripples in the McMurdo Dry Valleys. Boxes on left images indicate the areas shown in right images. (a) Small dust- and sand-covered snow
ripples in the Dry Valleys develop cracks in the dust cover along their crests. (b) An alternate view of the debris-covered ripples shows bare ground between them. Dark
central bars on scale card are 10 cm long. Photos taken by D. M. Hollibaugh Baker, 11/11/2010.
K.E. Scanlon et al. / Planetary and Space Science 111 (2015) 144–154
Fig. 14. Topography of a region of pits (examples highlighted with white arrows)
and knobs (examples highlighted with red arrows). Topographic contours from
HRSC DEM, superimposed on DEM-shaded CTX imagery. Contour interval is 5 m;
bold contour every 20 m. (For interpretation of the references to color in this figure
legend, the reader is referred to the web version of this article.)
equator, the Arsia Mons FSD may be a good target for human
missions to study martian ice while avoiding the logistical difficulties of a polar mission (e.g. Cockell, 2001).
Acknowledgments
We gratefully acknowledge support from the NASA Graduate Student Researchers Program (Grant NNX12AI39H) to KES, from the Mars
Data Analysis Program (Grant NNX11AI81G) and the Mars Express
High-Resolution Stereo Camera (HRSC) Investigation Team (JPL
1488322) to JWH, and from NSF Polar Programs (Grant ANT-0944702)
to DRM. We thank David Hollibaugh Baker for the use of his photographs in Fig. 13, and an anonymous reviewer for their constructive
suggestions.
References
Alley, R.B., 2000. Ice-core evidence of abrupt climate changes. Proc. Natl. Acad. Sci.
97 (4), 1331–1334.
Bazin, L., et al., 2013. An optimized multi-proxy, multi-site Antarctic ice and gas
orbital chronology (AICC2012): 120–800 ka. Clim. Past. 9, 1715–1731.
Belousov, A., Behncke, B., Belousova, M., 2011. Generation of pyroclastic flows by
explosive interaction of lava flows with ice/water-saturated substrate. J. Volcanol. Geotherm. Res. 202, 60–72.
Bennett, G.L., Evans, D.J.A., 2012. Glacier retreat and landform production on an
overdeepened glacier foreland: the debris-charged glacial landsystem at
Kviá ́rjökull, Iceland. Earth Surf. Process. Landf. 37, 1584–1602.
Boynton, W.V., et al., 2002. Distribution of hydrogen in the near surface of Mars:
evidence for subsurface ice deposits. Science 297 (5578), 81–85.
Campbell, B.A., Putzig, N.E., Carter, L.M., Morgan, G.A., Phillips, R.J., Plaut, J.J., 2013.
Roughness and near-surface density of Mars from SHARAD radar echoes.
J. Geophys. Res.: Planets 118, 436–450.
Capron, E., Landais, A., Chappellaz, J., Buiron, D., Fischer, H., Johnsen, S.J., Jouzel, J.,
Leuenberger, M., Masson-Delmotte, V., Stocker, T.F., 2012. A global picture of
153
the first abrupt climatic event occurring during the last glacial inception.
Geophys. Res. Lett. 39, L15703.
Chuang, F.C., Crown, D.A., 2005. Surface characteristics and degradational history of
debris aprons in the Tempe Terra/Mareotis fossae region of Mars. Icarus 179,
24–42.
Cockell, C.S., 2001. Martian polar expeditions: problems and solutions. Acta
Astronaut. 49 (12), 693–706.
Dickson, J.L., Head, J.W., 2006. Evidence for an Hesperian-aged south circum-polar
lake margin environment on Mars. Planet. Space Sci. 54, 251–272.
Dieterich, J.H., 1988. Growth and persistence of Hawaiian volcanic rift zones. J.
Geophys. Res.: Solid Earth 93 (B5), 4258–4270.
Dumke, A., Spiegel, M., Schmidt, R., Neukum, G., 2008. High-resolution digital terrain models and ortho-image mosaics of Mars: generation on the basis of Marsexpress HRSC data. Presented at Lunar and Planetary Science Conference
XXXIX. Abstract #1910.
Ebert, K., Kleman, J., 2004. Circular moraine features on the Varanger peninsula,
northern Norway, and their possible relation to polythermal ice sheet coverage.
Geomorphology 62 (3–4), 159–168.
Edwards, B., Magnússon, E., Thordarson, T., Guđmundsson, M.T., Höskuldsson, A.,
Oddsson, B., Haklar, J., 2012. Interactions between lava and snow/ice during the
2010 Fimmvörðuháls eruption, south-central Iceland. J. Geophys. Res.: Solid
Earth 117, B04302.
Elphic, R.C., Feldman, W.C., Prettyman, T.H., Tokar, R.L., Lawrence, D.J., Head, J.W.,
Maurice, S., 2005. Mars odyssey neutron spectrometer water-equivalent
hydrogen: comparison with glacial landforms on Tharsis. Presented at Lunar
and Planetary Science Conference XXXVI. Abstract #1805.
Evans, D.J.A., 2009. Controlled moraines: origins, characteristics and palaeoglaciological implications. Quat. Sci. Rev. 28 (3–4), 183–208.
Evans, D.J.A., 2011. Glacial landsystems of Satujökull, Iceland: a modern analogue
for glacial landsystem overprinting by mountain icecaps. Geomorphology, 129;
pp. 225–237.
Fastook, J.L., Head, J.W., Marchant, D.R., Forget, F., 2008. Tropical mountain glaciers
on Mars: altitude-dependence of ice accumulation, accumulation conditions,
formation times, glacier dynamics, and implications for planetary spin-axis/
orbital history. Icarus 198 (2), 305–317.
Fay, H., 2002. Formation of kettle holes following a glacial outburst flood (jökulhlaup), Skeidarársandur, southern Iceland In: Snorrason, A., Finnsdóttir, H.P.,
Moss, M.E. (Eds.), The Extremes of the Extremes: Extraordinary Floods. International Association of Hydrological Sciences, Wallingford, Oxfordshire, England, pp. 205–210.
Fiske, R.S, Jackson, E.D., 1972. Orientation and growth of Hawaiian volcanic rifts: the
effect of regional structure and gravitational stresses. P. Roy. Soc. Lond. A. 329,
299–326.
Forget, F., Haberle, R., Montmessin, F., Levrard, B., Head, J., 2006. Formation of
glaciers on Mars by atmospheric precipitation at high obliquity. Science 311
(5759), 368–371.
Hambrey, M.J., 1984. Sedimentary processes and buried ice phenomena in the proglacial areas of Spitsbergen glaciers. J. Glaciol. 30 (104), 116–119.
Head, J.W., Marchant, D.R., 2003. Cold-based mountain glaciers on Mars: Western
Arsia Mons. Geology 31 (7), 641–644.
Head, J.W., Mustard, J.F., Kreslavsky, M.A., Milliken, R.E., Marchant, D.R., 2003.
Recent ice ages on Mars. Nature 426, 797–802.
Head, J.W., Marchant, D.R., Agnew, M.C., Fassett, C.I., Kreslavsky, M.A., 2006a.
Extensive valley glacier deposits in the northern mid-latitudes of Mars: evidence for Late Amazonian obliquity-driven climate change. Earth Planet.
Sci. Lett. 241, 663–671.
Head, J.W., Nahm, A.L., Marchant, D.R., Neukum, G., 2006b. Modification of the
dichotomy boundary on Mars by Amazonian mid-latitude regional glaciation.
Geophys. Res. Lett. 33, L08S03.
Head, J.W., Marchant, D.R., Dickson, J.L., Kress, A.M., Baker, D.M.H., 2010. Northern
mid-latitude glaciation in the late Amazonian period of Mars: criteria for the
recognition of debris-covered glacier and valley glacier landsystem deposits.
Earth Planet. Sci. Lett. 294, 306–320.
Head, J.W., Weiss, D.K., 2014. Tropical mountain glacier deposits on Mars: preservation of ancient ice at Pavonis and Arsia Mons. Icarus 103, 331–338.
Holt, J.W., Safaeinili, A., Plaut, J.J., Head, J.W., Phillips, R.J., Seu, R., Kempf, S.D.,
Choudhary, P., Young, D.A., Putzig, N.E., Biccari, D., Gim, Y., 2008. Radar
sounding evidence for buried glaciers in the southern mid-latitudes of Mars.
Science 322, 1235–1238.
Irvine-Fynn, T.D.L., Barrand, N.E., Porter, P.R., Hodson, A.J., Murray, T., 2011. Recent
high-Arctic glacial sediment redistribution: a process perspective using airborne lidar. Geomorphology 125 (1), 27–39.
Jakosky, B.M., Carr, M.H., 1985. Possible precipitation of ice at low latitudes of Mars
during periods of high obliquity. Nature 315 (6020), 559–561.
Kadish, S.J., Head, J.W., Parsons, R.L., Marchant, D.R., 2008a. The Ascraeus Mons fanshaped deposit: volcano–ice interactions and the climatic implications of coldbased tropical mountain glaciation. Icarus 197 (1), 84–109.
Kadish, S.J., Head, J.W., Barlow, N.G., Marchant, D.R., 2008b. Martian pedestal craters: marginal sublimation pits implicate a climate-related formation
mechanism. Geophys. Res. Lett. 35, L16104.
Kadish, S.J., Head, J.W., 2011. Impacts into non-polar ice-rich paleodeposits on
Mars: excess ejecta craters, perched craters and pedestal craters as clues to
Amazonian climate history. Icarus 215, 34–46.
Kadish, S.J., Head III, J.W., Fastook, J.L., Marchant, D.R., 2014. Middle to Late Amazonian tropical mountain glaciers on Mars: the ages of the Tharsis Montes fanshaped deposits. Planet. Space Sci. 91, 52–59.
154
K.E. Scanlon et al. / Planetary and Space Science 111 (2015) 144–154
Knight, J., 2012. Glaciotectonic sedimentary and hydraulic processes at an oscillating ice margin. Proc. Geol. Assoc. 123, 714–727.
Kobashi, T., Kawamura, K., Severinghaus, J.P., Barnola, J.-M., Nakaegawa, T., Vinther,
B.M., Johnsen, S.J., Box, J.E., 2011. High variability of Greenland surface temperature over the past 4000 years estimated from trapped air in an ice core.
Geophys. Res. Lett. 38, L21501.
Koster, E.A., Dijkmans, J.W.A., 1988. Niveo-aeolian deposits and denivation forms,
with special reference to the great Kobuk Sand Dunes. Northwestern Alaska,
Earth Surf. Processes 13, 153–170.
Kowalewski, D.E., Marchant, D.R., Head, J.W., Jackson, D.W., 2012. A 2D model for
characterizing first-order variablility in sublimation of buried glacier ice, Antarctica: assessing the influence of polygon troughs, desert pavements, and
shallow-subsurface salts. Permafrost Periglac. Process. 23, 1–14. http://dx.doi.
org/10.1002/ppp.731.
Kowalewski, D.E., Marchant, D.R., Levy, J.S., Head III, J.W., 2006. Quantifying low
rates of summertime sublimation for buried glacier ice in Beacon Valley, Antarctica. Antarct. Sci. 18, 421–428.
Kress, A.M., Head, J.W., 2008. Ring-mold craters in lineated valley fill and lobate
debris aprons on Mars: evidence for subsurface glacial ice. Geophys. Res. Lett.
35, L23206.
Lacelle, D., Davila, A.F., Pollard, W.H., Andersen, D., Heldmann, J., Marinova, M.,
McKay, C.P., 2011. Stability of massive ground ice bodies in University Valley,
McMurdo Dry Valleys of Antarctica: using stable O–H isotope as tracers of
sublimation in hyper-arid regions. Earth Planet. Sci. Lett. 301 (1–2), 403–411.
Lakeman, T.R., England, J.H., 2012. Paleoglaciological insights from the age and
morphology of the Jesse moraine belt, western Canadian Arctic. Q. Sci. Rev. 47,
82–100.
Laskar, J., Correia, A.C.M., Gastineau, M., Joutel, F., Levrard, B., Robutel, P., 2004. Long
term evolution and chaotic diffusion of the insolation quantities of Mars. Icarus
170 (2), 343–364.
Lefort, A., Russell, P.S., Thomas, N., 2010. Scalloped terrains in the Peneus and
Amphitrites Paterae region of Mars as observed by HiRISE. Icarus 205, 259–268.
Levine, J.S., Garvin, J.B., Head, J.W., 2010. Martian geology investigations: planning
for the scientific exploration of mars by humans, Part 2. J. Cosmol. 12,
3636–3646.
Levy, J., Head, J.W., Marchant, D.R., Kowalewski, D., 2008. Identification of sublimation-type thermal contraction crack polygons at the proposed NASA
phoenix landing site: implications for substrate properties and climate-driven
morphological evolution. Geophys. Res. Lett. 35, L04202.
Levy, J.S., Head, J.W., Marchant, D.R., 2009. Concentric crater fill in Utopia Planitia:
history and interaction between glacial “brain terrain” and periglacial mantle
processes. Icarus 202, 462–476.
Levy, J.S., Head III, J.W., Marchant, D.R., 2010. Concentric crater fill in the northern
mid-latitudes of Mars: formation processes and relationships to similar landforms of glacial origin. Icarus 209, 390–404.
Levy, J.S., Fassett, C.I., Head, J.W., Schwartz, C., Watters, J.L., 2014. Sequestered
glacial ice contribution to the global martian water budget: geometric constraints on the volume of remnant, mid-latitude debris covered glaciers.
J. Geophys. Res.: Planets 119 (8), 2188–2196.
Lucchitta, B.K., 1981. Mars and Earth-comparison of cold-climate features. Icarus
45 (2), 264–303.
Lüthi, D., et al., 2008. High-resolution carbon dioxide concentration record
650,000–800,000 years before present. Nature 453, 379–382.
Mackay, S.L., Marchant, D.R., Head, J.W., Lamp, J.L., 2014. Cold-based debris-covered
glaciers: evaluating their potential as climate archives through studies of
ground-penetrating radar and surface morphology. J. Geophys. Res. Earth Surf.
119. http://dx.doi.org/10.1002/ 2014JF003178.
Malin, M.C., et al., 2007. Context camera investigation on board the Mars reconnaissance orbiter. J. Geophys. Res.: Planets 112 (E05).
Mangold, N., Allemand, P., 2001. Topographic analysis of features related to ice on
Mars. Geophys. Res. Lett. 28, 407–410.
Mangold, N., 2003. Geomorphic analysis of lobate debris aprons on Mars at Mars
orbiter camera scale: evidence for ice sublimation initiated by fractures.
J. Geophys. Res.: Planets 108 (E4), 2-1–2-13.
Mangold, N., 2011. Ice sublimation as a geomorphic process: a planetary perspective. Geomorphology 126 (1), 1–17.
Marchant, D.R., Lewis, A., Phillips, W.C., Moore, E.J., Souchez, R., Landis, G.P., 2002.
Formation of patterned-ground and sublimation till over Miocene glacier ice in
Beacon valley, Antarctica. Geol. Soc. Am. Bull. 114, 718–730.
Marchant, D.R., Head, J.W., 2007. Antarctic dry valleys: microclimate zonation,
variable geomorphic processes, and implications for assessing climate change
on Mars. Icarus 192 (1), 187–222. http://dx.doi.org/10.1016/j.icarus.2007.06.018.
McTigue, D.F., Mei, C.C., 1981. Gravity-induced stresses near topography of small
slope. J. Geophys. Res.: Solid Earth 86 (B10), 9268–9278.
Mellon, M.T., Jakosky, B.M., 1993. Geographic variations in the thermal and diffusive
stability of ground ice on Mars. J. Geophys. Res.: Planets 98 (E2), 3345–3364.
Mellon, M.T., Jakosky, B.M., 1995. The distribution and behavior of martian ground
ice during past and present epochs. J. Geophys. Res.: Planets 100 (E6),
11781–11799.
Mellon, M.T., Jakosky, B.M., Postawko, S.E., 1997. The persistence of equatorial
ground ice on Mars. J. Geophys. Res.: Planets 102 (E8), 19357–19369.
Monnier, S., Camerlynck, C., Rejiba, F., 2008. Ground penetrating radar survey and
stratigraphic interpretation of the Plan du Lac rock glaciers, Vanoise Massif,
Northern French Alps. Permafr. Periglac. Proces 19 (1), 19–30.
Mustard, J.F., Cooper, C.D., Rifkin, M.K., 2001. Evidence for recent climate change on
Mars from the identification of youthful near-surface ground ice. Nature 412
(6845), 411–414.
Neukum, G., Jaumann, R., 2004. HRSC: The High Resolution Stereo Camera of Mars
Express In: Wilson, A. (Ed.), Mars Express: The Scientific Payload. European
Space Agency, The Netherlands, pp. 17–35.
Pedersen, G.B., Head, J.W., 2010. Evidence of widespread degraded Amazonian-aged
ice-rich deposits in the transition between elysium rise and Utopia planitia,
Mars: guidelines for the recognition of degraded ice-rich materials. Planet.
Space Sci. 58, 1953–1970.
Pierce, T.L., Crown, D.A., 2003. Morphologic and topographic analyses of debris
aprons in the eastern Hellas region, Mars. Icarus 163, 46–65.
Plaut, J.J., Safaeinili, A., Holt, J.W., Phillips, R.J., Head, J.W., Seu, R., Putzig, N.E., Frigeri,
A., 2009. Radar evidence for ice in lobate debris aprons in the mid-northern
latitudes of Mars. Geophys. Res. Lett. 36, L02203.
Price, R.J., 1969. Moraines, Sandar, kames and Eskers near Breidamerkurjökull,
Iceland. Trans. Inst. Br. Geogr. 46, 17–43.
Rhodes, R.H., Faïn, X., Stowasser, C., Blunier, T., Chappellaz, J., McConnell, J.R.,
Romanini, D., Mitchell, L.E., Brook, E.J., 2013. Continuous methane measurements from a late holocene Greenland ice core: atmospheric and in-situ signals.
Earth Planet. Sci. Lett. 368, 9–19.
Rubin, D.M., Rubin, A.M., 2013. Origin and lateral migration of linear dunes in the
Qaidam Basin of NW China revealed by dune sediments, internal structures,
and optically stimulated luminescence ages, with implications for linear dunes
on Titan: discussion. Geol. Soc. Am. Bull. 125, 1943–1946.
Russell, A.J., Tweed, F.S., Roberts, M.J., Harris, T.D., Gudmundsson, M.T., Knudsen, O.,́
Marren, P.M., 2010. An unusual jökulhlaup resulting from subglacial volcanism,
Sólheimajökull, Iceland. Q. Sci. Rev. 29, 1363–1381.
Sanford, R.A., 1959. Analytical and experimental study of simple geologic structures. Geol. Soc. Am. Bull. 70, 19–51.
Scott, D., Zimbelman, J., 1995. Geologic map of Arsia Mons Volcano. Mars US
Geological Survey Miscellaneous Gteologic Investigation Map I-2480.
Scanlon, K.E., Head, J.W., Wilson, L., Marchant, D.R., 2014. Volcano–ice interactions
in the Arsia Mons tropical mountain glacier deposits. Icarus 237, 315–339.
Scanlon, K.E., Head, J.W., Marchant, D.R., 2015. Local, volcanism-induced wet-based
glacial conditions recorded in the Late Amazonian Arsia Mons tropical mountain glacier deposits. Icarus 250, 18–31.
Schon, S.C., Head III, J.W., 2012. Decameter-scale pedestal craters in the tropics of
Mars: evidence for the recent presence of very young regional ice deposits in
Tharsis. Earth Planet. Sci. Lett. 317-318, 68–75.
Schorghofer, N., Forget, F., 2012. History and anatomy of subsurface ice on Mars.
Icarus 220, 1112–1120.
Séjourné, A., Costard, F., Gargani, J., Soare, R.J., Fedorov, A., Marmo, C., 2011. Scalloped depressions and small-sized polygons in western Utopia Planitia, Mars: a
new formation hypothesis. Planet. Space Sci. 59, 412–422.
Shean, D.E., Head, J.W., Marchant, D.R., 2005. Origin and evolution of a cold-based
tropical mountain glacier on Mars: the Pavonis Mons fan-shaped deposit. J.
Geophys. Res.: Planets 110 (E5).
Shean, D.E., Head, J.W., Fastook, J.L., Marchant, D.R., 2007. Recent glaciation at high
elevations on Arsia Mons, Mars: implications for the formation and evolution of
large tropical mountain glaciers. J. Geophys. Res.: Planets 112 (E3).
Smith, D.E., et al., 1999. The global topography of Mars and implications for surface
evolution. Science 284 (5419), 1495–1503.
Sridhar, K.R., Iacomini, C.S., Finn, J.E., 2004. Combined H2O/CO2 solid oxide electrolysis for Mars in situ resource utilization. J. Propul. Power 20 (5), 892–901.
Sugden, D.E., Marchant, D.R., Potter Jr., N., Souchez, R.A., Denton, G.H., Swisher III, C.C.,
Tison, J.-L., 1995. Preservation of Miocene glacier ice in East Antarctica. Nature
376, 412–414.
Swanger, K.M., Marchant, D.R., Kowalewski, D.E., Head, J.W., 2010. Viscous flow
lobes in central Taylor valley, Antarctica: origin as remnant buried glacial ice.
Geomorphology 120, 174–185. http://dx.doi.org/10.1016/j.
geomorph.2010.03.024.
Szuman, I., Kasprzak, L., 2010. Glacier ice structures influence on moraine development (Hørbye Glacier, Central Spitsbergen). Quaest. Geogr. 29, 65–73.
Thwaites, F.T., 1926. The origin and significance of pitted outwash. J. Geol. 34 (4),
308–319.
Williams, R., 1978. Geomorphic processes in Iceland and on Mars: a comparative
appraisal from orbital images. Geol. Soc. Am. Abstr. Progr. 10, 517.
Zimbelman, J.R., Edgett, K.S., 1992. The Tharsis Montes, Mars – comparison of
volcanic and modified landforms. Presented at Lunar and Planetary Science
Conference XXII, pp. 31–44.
Zuber, M.T., Smith, D.E., Solomon, S.C., Muhleman, D.O., Head, J.W., Garvin, J.B.,
Abshire, J.B., Bufton, J.L., 1992. The Mars-observer laser altimeter investigation.
J. Geophys. Res.: Planets 97 (E5).