Fluvial geomorphology on Earth-like planetary surfaces: A review

Abstract

Morphological evidence for ancient channelized flows (fluvial and fluvial-like landforms) exists on the surfaces of all of the inner planets and on some of the satellites of the Solar System. In some cases, the relevant fluid flows are related to a planetary evolution that involves the global cycling of a volatile component (water for Earth and Mars; methane for Saturn's moon Titan). In other cases, as on Mercury, Venus, Earth's moon, and Jupiter's moon Io, the flows were of highly fluid lava. The discovery, in 1972, of what are now known to be fluvial channels and valleys on Mars sparked a major controversy over the role of water in shaping the surface of that planet. The recognition of the fluvial character of these features has opened unresolved fundamental questions about the geological history of water on Mars, including the presence of an ancient ocean and the operation of a hydrological cycle during the earliest phases of planetary history. Other fundamental questions posed by fluvial and fluvial-like features on planetary bodies include the possible erosive action of large-scale outpourings of very fluid lavas, such as those that may have produced the remarkable canali forms on Venus; the ability of exotic fluids, such as methane, to create fluvial-like landforms, as observed on Saturn's moon, Titan; and the nature of sedimentation and erosion under different conditions of planetary surface gravity. Planetary fluvial geomorphology also illustrates fundamental epistemological and methodological issues, including the role of analogy in geomorphological/geological inquiry.

Keywords: Fluvial channels; Mars; Planetary geomorphology; Titan; Venus; Volcanic channels.

Fig. 1

Apollo 15 image AS15-93-12628 showing Vallis Schröteri (Schröter’s Valley) on the Moon. Typical for lunar sinuous rilles, the valley’s maximum width (11 km) and depth (about 500 m) occur near its source. It narrows distally over about 160 km to less than a kilometer wide near its terminus, where it grades into volcanic plains that resulted from the immense amounts of lava that coursed through the channel. This is one of the largest sinuous rilles on the Moon. The astronomer Johann Hieronymus Schröter first observed it with a telescope in 1797. The sun direction for the image is from the upper left.

Fig. 2

Portion of the Mercury lava channel Angkor Vallis at 57° N latitude, 115° E longitude. The image is from the Mercury Dual Imaging System (MDIS) of the MESSENGER spacecraft and has a resolution of 250 m per pixel.

Fig. 3

Examples of simple channels on Venus (all examples are Magellan left-looking SAR images): (A) simple channel with flow margin; (B) sinuous rille; and (C) a canali-type channel (Baltis Vallis). Arrows show the channel locations, and north is up in this figure.

Fig. 4

Examples of complex channels and compound channels on Venus (all are Magellan left-looking SAR images: A) complex channel with flow margin; B) complex channel without flow margin; C) compound channel (Kallistos Vallis). Arrows show the channel locations, and north is up in this figure.

Fig. 5

Mosaic of images taken by the Descent Imager/Spectral Radiometer (DISR) on the Huygens probe during descent to the surface of Titan showing fluvial networks. Image quality varies across the mosaic as a function of the amount of haze between the camera and the surface. North is up, and the mage is ~6 km wide, so that the most prominent network in the center of the mosaic is ~4 km from west to east. Image courtesy of National Aeronautics and Space Administration (NASA)/Jet Propulsion Laboratory (JPL)/European Space Agency (ESA)/U. Arizona.

Fig. 6

(A) Colorizedmosaic of Titan Radar Mapper synthetic aperture radar (SAR) images of the northern lakes region of Titan. The scene shows a large dark region, Ligeia Mare, interpreted to be a shallow lake of liquid methane. An example of a narrow, elongate valley can be seen in the lower right of the image, feeding into a drowned network. Other drowned valleys are visible along the lake margins to the west and east. Ligeia Mare is ~400 km in maximum north–south extent (along longitude lines). The North Pole is off the image to the upper left. SAR image quality varies across the mosaic. The inset (B) shows the location of the image on the right. Right: Another drowned network near the lower center of the image is shown in more detail in the black-and-white SAR image. Images courtesy of National Aeronautics and Space Administration (NASA)/Jet Propulsion Laboratory (JPL)/European Space Agency (ESA)/U. Arizona.

Fig. 7

Mosaic of synthetic aperture radar (SAR) images from the Titan Radar Mapper of the Cassini Mission, showing narrow, elongate fluvial valleys in the Xanadu region, approximately 100° S, 1370° Won Titan. On this image, fluvial feature are bright, which is hypothesized for other radar-bright fluvial features to result from internal reflections from cobble-sized debris. SAR image quality varies across the mosaic. North is up in this figure. Image courtesy of National Aeronautics and Space Administration (NASA)/Jet Propulsion Laboratory (JPL)/European Space Agency (ESA)/U. Arizona.

Fig. 8

Rounded cobbles imaged by the Huygens probe at its landing site. The largest clast in the image is about 15 cm in diameter.

Fig. 9

Map of Mars showing the distribution of small valleys in red and possible extents of ancient inundation to up to topographic level of–3780 m (dark blue) and–1680 m (light blue). The possible inundation levels correspond to the Contact 2 (lower level) and Contact 1 (higher level) shorelines defined by Parker et al. (1989, , which were renamed respectively the Deuternolilus and Arabia Shorelines by Clifford and Parker (2001). Other features indicated by letters are volcanoes, B—Alba Patera, E—Elysium Mons, O—Olympus Mons, TV—Tharsis volcanoes, Y—Syrtis Major Planitia, and Z—Hecates Tholis; impact basins and craters, A—Argyre, C—Chryse, F—Jezero Crater, G—Gale Crater, H—Hellas; deltas-F—Jezero, U—Eberswalde; tectonic features, N—Noctis Labyrinthus, V—Valles Marineris; channels and valleys, D—Okavango Vallis, I—Athabasca Vallis, J—Maja Vallis, K—Kasei Vallis, L—Mangala Vallis, M—Ma’adim Vallis, P—Marte Vallis, Q—Warrego Vallis, R—Hrad Vallis, S—Shalbatana Vallis, T—Tiu and Simud Valles, U—Uzboi Vallis, W—Mawth Vallis, X—Aram Chaos and channel. The valleys were extracted from Mars Orbiter Laser Altimeter (MOLA) digital elevation model (DEM) data using a computer algorithm that recognizes valleys by their concave upward morphologic signature, aided by visual inspection against Thermal Emission Imaging System (THEMIS) imagery to remove any false positive identifications by the algorithm (see Luo and Stepinski, 2009).

Fig. 10

Fluvial network dissection of the heavily cratered highlands of Mars. Elevation data from the Mars Observer Laser Altimeter was combined with imagery so that low-lying areas are indicated in darker shades of blue and higher areas in darker shades of brown. North is up in this figure.

Fig. 11

Fluvial conglomerate imaged by the Curiosity Lander of the Mars Science Laboratory Mission.

Fig. 12

Peace alluvial fan, the site of the Curiosity landing in Gale Crater, Mars. The small cross shows that actual landing site, and the dark ellipse outlines the planned landing zone. Note the red colors indicating high thermal inertia measured with the Thermal Emission Imaging System (THEMIS) on the Mars Odyssey spacecraft. These are areas of finer-grained sediments at the distal end of the alluvial fan.

Fig. 13

(A) Image of Eberswalde delta taken by the High-Resolution Stereo Camera (HRSC) of the Mars Express spacecraft. The delta surface is marked by alluvial paleochannels that fed into a lake that occupied the Eberswalde crater. The inset (B) shows the location of the figure on the right. Right: Detail of the distributary complex of alluvial channels imaged by the Mars Orbiter Camera (MOC). The channel sediments, presumably sand and/or gravel, are etched into positive relief because of the erosional removal of adjacent materials, presumably overbank silt and/or clay. Note the prominent scroll bar topography associated with the meander bend near the center of the image. North is up in each figure.

Fig. 14

Composite imager generated from data from the Mars Reconnaissance Orbiter(MRO) Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and Context (CTX) Imager data. The background is composed on a CTX image with a resolution of 6 m per pixel resolution, and the spectrometer data are show for the following wavelengths: 2.38 μm(red), 1.80 μm (green), and 1.15 μm (blue), which were acquired at 35 m/pixel resolution from CRISM image HRL000040FF. North is up in this figure.

Fig. 15

(A) Crater gullies southeast of Gorgonium Chaos. Note the detail of gullies that have eroded into bedrock of the proximal source regions shown in (B) and into distal surfaces shown in (C) of drainages off the inner rim of an impact crater shown in (A). North is up in each figure.

Fig. 16

(A) A portion of Mars Reconnaissance Orbiter (MRO)High Resolution Imaging Science Experiment (HiRISE) image PSP_1712_1405 (0.3 m/pixel resolution) showing theater headed gully tributaries with inner channels (left). Sun direction is from the left, and north is up. (B) Portion of HiRISE image PSP_001415_1877 (0.3 m/pixel resolution). The image shows the eastern rim region of Mojave crater, which is extensively dissected by integrated gully systems. North is up in the figure, and the sun is illuminating from the left.

Fig. 17

Portion of High Resolution Imaging Science Experiment (HiRISE) image ESP_011753_1445 (0.3 m/pixel resolution), showing gullies along the eastern rim of Hale Crater. Gullies with different orientations are developed on both sides of the ridge running through the center of the image. Note bright deposits along some gullies. North is up in the figure, and the sun is illuminating from the left.

Fig. 18

Portion of High Resolution Imaging Science Experiment (HiRISE) color image PSP_002932_1445 (0.3 m/pixel resolution) showing greater detail of the Hale Crater gullies. North is up in the image, and the sun is illuminating from the left.

Fig. 19

Lava channel formation scenarios: (A) partially drained channel bounded by confining levees; (B) broad sheet-like lava lobe bounded by the initial topography; (C) deep channel formed by thermal-mechanical erosion into the substrate followed by partial drainage of the preferred lava pathway; (D) deep channel formed by constructional processes followed by lava drainage without substrate erosion.

Fig. 20

Examples of terrestrial lava channels: (Left) example of an active lava channel forming on Kīlauea, Hawaii, during the 2007–2008 phase of the Pu’u ‘Ō’ō eruption; (Right) example of a 5-m-deep channel formed within the 1783–1784 A.D. Laki eruption in Iceland.

Fig. 21

Examples of partially drained lava channels on Mars: (A) digital terra in model (DTM) (1 m/pixel) derived from High Resolution Imaging Science Experiment (HiRISE) stereo-images ESP 012444 2065 and ESP_014000_2065; and (B) DTM (1 m/pixel) derived from HiRISE stereo-images ESP_019235_2050 and ESP_018945_2050. North is up in each figure.

Fig. 22

Map of eastern Tharsis and circum-Chryse areas of Mars on MOLA topographic base (low areas in blue, high areas in red and brown). Features indicated by letters include volcanoes, I—Alba Patera, P—Pavonis Mons, Q—Arsia Mons, Z—Ascraeus Mons; impact basins and craters, C—Chryse, H—Holden; delta—Eberswalde; tectonic features, N—Noctis Labyrinthus, VM—Valles Marineris; channels and valleys, A—Ares, B—Columbia and Daga Valles, D—Simud Vallis, F—Nanedi Vallis, G—Nirgal Vallis, J—Maja Vallis, K—Kasei Vallis, L—Ladon Vallis, M—Morava Vallis, O—Osuga Vallis, R—Ravi Vallis, S—Shalbatana Vallis, T—Tiu Vallis, U—Uzboi Vallis, W—Mawth Vallis, X—Aran Chaos and channel, Y—Iani Chaos.

Fig. 23

Mouth of Kasei, the largest and longest (2400 km) “outflow channel” on Mars. This oblique view was generated at 2× vertical exaggeration from the THEMIS data acquired by the Mars Odyssey spacecraft. The view is upstream, and the large crater in the center is Sharonov, which is 100 km in diameter. Note the splitting and convergence of channels (anastomosis).

Fig. 24

Streamlined features in Ares Vallis (15.9° N, 330° E) imaged at visible wavelengths by the Thermal Emission Imaging System (THEMIS) on NASA’s Mars Odyssey orbiter. The cataclysmic flooding came from the lower right. Lins is the post-flooding, fresh looking crater in the lower right. It is about 6 km in diameter, and the imaged scene is about 40 × 50 km. The streamlined features probably developed by a combination of deposition and preservation of pre-flood bedrock downstream from obstructions to the cataclysmic flood flows. There are also smaller-scaled lineated forms that may have developed as grooves or as depositional accumulations behind small obstructions. They are oriented longitudinally relative to the cataclysmic flood flows. Some intriguing transverse bedforms occur in the upper left quadrant of the image. These have orientations similar to what would be expected for subfluvial dunes, but at a spacing of about 500 m they are even larger that would occurs in terrestrial cataclysmic flooding channels. North is up in the figure.

Fig. 25

Expansion bar complex in Osuga Vallis. This is an oblique view generated data provided by the High Resolution Stereo Camera (HRSC) on the Mars Express spacecraft. The view is downstream, and the channel width is about 20 km. The regional context for this image is shown in Fig. 29.

Fig. 26

Kasei Vallis (bottom right quadrant) entering the northern plains of Mars as shown on a topographic base provided by the MOLA instrument on Mars Global Surveyor. Note the transitions from the cataclysmic flooding channels directly into the northern plains without extensive sediment accumulation. The mouth of Kasei in the lower center of the image is also shown in Fig. 23.

Fig. 27

Ravi Vallis. A 200-km long catastrophic flooding channel that emanates from Aromatum Chaos (left). Note the erosion of two chaos zones in the channel (center) and distal spilling of the channel-forming fluid over and the plateau edge to disappear into another chaos region (right foreground). This oblique view was generated from the Mars Odyssey spacecraft using the THEMIS instrument with a vertical exaggeration of about 1.5×.

Fig. 28

High Resolution Stereo Camera (HRSC) image of Osuga Vallis. This relatively short cataclysmic flooding channel has length of ~160 km, but its depth is up to 900 m. The expansion bar complex in the upper center portion of the image is also shown in Fig. 25. The cataclysmic floodwaters flowed toward the northeast (lower right in the image), entering a depression at the lower right of the image. The floodwater entering this depression must have been able to drain away very quickly, probably into the adjacent chasmata canyons of the Valles Marineris (Fig. 22). Otherwise, the water would have ponded, preventing the erosion of the channel. Subterranean conduits would have been necessary to convey the immense flows. North is to the right in this figure.

Fig. 29

Sketch map of the western hemisphere of Mars, showing the 8000 km drainage system, including the Uzboi–Ladon–Margaritifer (ULM) system, that extends to the northern plains (‘Oceanus Borealis’) from the layered deposits (LD) that underlie the South Polar Cap (SPC). Elements of the drainage include (from south to north): Dzigai Vallis (D), the Argyre impact basin, Uzboi Vallis (U), Holden Crater (H), Ladon Vallis (L), Ladon Basin (LB), Margaritifer Vallis (M), and Ares Vallis (A). Other prominent cataclysmic flooding channels include Mangala Vallis (N), Kasei Vallis (K), Maja Valis (J), and Shalbatana Vallis (S).

Fig. 30

Oblique view with a 2× vertical exaggeration of a portion of the Uzboi–Ladon–Margaritifer (ULM) system generated from visible THEMIS data acquired by the Mars Odyssey spacecraft. The view is toward the southwest, showing the mouth of Uzboi Vallis (center) into Holden Crater through its southern rim. There is a fan-like accumulation of layered sediments at this junction, and a possible landing site for the Mars Science Laboratory rover was proposed for the flat, smooth area at right center, close to where the channel cuts through the rim.