Continuing the exploration of the northern hemisphere elevation dichotomy boundary eastward, the Nilosyrtis Mensae area is also rich in Souness glacier-like forms:
|HRSC DTMs blended with nadir image.|
|This is the elevation colour ramp used for all HRSC DTMs in this region.|
|MOLA elevation blended with hillshade.|
Auqukuh Vallis (word for 'Mars' in Quechua)
The Auqukuh Vallis system shows some striking examples of GLFs, and is highly favoured by the Bayesian classifier:
|HRSC DTM (tile h1446 at 61°E, 31°N) blended with nadir image. Two Souness GLFs are found within this area, including HiRISE anaglyph coverage of the terminus of S312 (PSP_003482_2115).|
|The nadir image alone.|
|Nadir image with classifier for head (red) and extent (blue) areas overplotted.|
Another part of the Auqukuh Vallis system at 62°E, 32°N:
|Five Souness GLFs are shown in this region, with HRSC DTMs of h1446 and h5173 overlaid on nadir images.|
|Nadir image alone|
|With classifier overplotted.|
|A curious feature at 62.5°E, 32.5°N.|
Around 68°-75°E, 28°-34°N:
|HRSC DTM tiles (h1391, h5378, h5360, h5342, h5324, h5306) blended with nadir image.|
|Nadir images only.|
|Nadir images with classifier overplotted.|
The HiRISE anaglyphs ESP_013160_2135
are in the vicinity of, but do not overlap Souness GLFs.
Closeup of part of tile h5342:
|Many Souness GLFs are to be found in this area around 73°E, 30°N.|
|The classifier picks out areas of the south side of the mesa which do not have Souness GLFs catalogued. Is it possible that glaciers in south facing areas at this relatively low latitude for Souness GLFs were ablated more readily?|
Closeup of part of tile h5306 around 75°E, 30°N:
|Again the 2 Souness catalogued GLFs are found on the northern side of the mesa only. |
Close up of h5234/h5306, showing an area further south at 28-29°N:
|The southern valleys below 28°N have no Souness catalogued GLFs. The set around 74°E, 28.5°N are the southernmost Souness GLFs in the entire northern hemisphere, except S201 at 77.15°E, 27.78°N at two others in crater Lockyer at 160°E. 27.5°N. |
|Nadir images only|
|Nadir images with classifier.|
|A closer view. The size of the alcoves suggests that the GLFs here may be the remnants of larger objects that have ablated.|
To the east of the Deuteronilus Mensae region in the northern mid-latitudes of Mars, there is the Protonilus Mensae region, also on the elevation dichotomy boundary, and there are many Souness GLFs found there.
|HRSC tiles with elevation blended with nadir image.|
|Elevation colour ramp used for all the HRSC DTMs in this area.|
|MOLA elevation blended with hillshade|
There are rather more than I will have the opportunity to examine in any fine detail here, but here are several regions showing Souness GLF extents, and where 3D anaglyph coverage exists. Hopefully the labels of these are large enough to be visible, and you can look these up at www.uahirise.org/anaglyph
Near Moreaux crater (centred ~ 43°E, 43°N)
Several HiRISE 3D anaglyphs are found overlapping or in the vicinity of Souness GLFs:
North of Rudeau crater (~ 53°E, 41°N)
Coloe Fossae area ( ~ 56°E, 36°N)
Souness 364 (55°E, 41°N)
This region was been studied in detail in a paper published by Souness & Hubbard (2013)
who addressed the question of whether it was formed by ice moving into the alcove in a former time when there was a widespread ice sheet in the region and later downwasted, or by ice moving out of the alcove more recently, favouring the latter hypothesis.
|Unfortunately most of S364 is covered only by a 150m resolution DTM though other GLFs in the area are covered at 75m resolution.|
|The classifier shows terrain similar to GLF head areas surrounding S364.|
The northern hemisphere elevation dichotomy boundary, between the flat plains in the north and the highlands to the south is where a large number of glacial landforms have been seen.
Here is the area around Deuteronilus Mensae:
|Summary of general area, with elevation blended with MOC mosaic, and HRSC tiles overlaid with colour-coded elevation blended with nadir image.|
|Colour-coded MOLA elevation alone|
|MOLA elevation, blended with hillshade|
A crater at 6°W, 38°N, with two Souness GLFs in the crater wall within the HRSC tile h5314.
|Elevation blended with HRSC nadir image. Souness 1 is the lowest elevation GLF in this part of the northern hemisphere (there is a cluster around 120°E, 40°N that are lower) at a head elevation of -4222m. |
|The classifier, showing topographic similarity to head and extents of Souness GLFs.|
There are several HiRISE images available of this crater, including ESP_019070_2185
, and a 3D anaglyph ESP_034287_2185.
Showing an area around 16°E, 37°N within tiles h5321, h5303, h5285, h5267 and h5249. A number of Souness GLFs are evident.
|There are two HiRISE 3D anaglyphs overlapping Souness GLFs in this area.|
An area around 24°E, 37°N, with a number of Souness GLFs with anaglyphs in the vicinity of, but not overlapping them. At the lower right, there is a high resolution HiRISE DTM available for the area south of Souness 659.
An area at 29°E, 41°N in HRSC tiles h1450 and h1426, containing a number of Souness GLFs.
Lyot crater at 30°E, 50°N is the deepest point in the Northern Hemisphere of Mars with a floor elevation of ~ -7000m. There are no Souness GLFs found in it, although the classifier does pick up substantial areas of topographic similarity to extent and head areas. The has been a study showing evidence for liquid water and fluvial activity in the (relatively) recent past: Dickson et al. 2009.
Here is a series of Google Earth screenshots of part of Lyot, with the CTX imagery mosaic:
|From near the centre of the crater, looking S. A large area of dark dunes is seen in the foreground. |
|Moving south, across some mountains within the crater rising to about ~-4000m.|
|The southern outer wall perhaps showing some remnants of glacial activity? This would be interesting, because given studies arguing for a microclimate allowing for liquid water at relatively late epochs, perhaps there is a critical elevation below which glaciers were not preserved due to higher ablation, with a thicker atmosphere at the lowest elevations allowing more wind erosion and high temperatures?|
Continuing the northern Martian mid-latitudes, here is the Mareotis Fossae area:
|The HRSC tiles, with DTM overlaid in green on the grayscale nadir image.|
|All of the HRSC tiles use the above colour scheme for the elevation.|
|The MOLA DTM elevation colour-coded.|
|The MOLA elevation colour ramp.|
|The MOLA DTM hillshaded.|
Tanaica Montes area at 90°W, 40°N:
Tempe Colles area (85°W, 35°N)
|Certain areas have substantial amounts of terrain favoured by the classifier as being topographically similar to glacier head or extent areas but have few Souness GLFs.|
|Baphyrus Catena at 84°W, 39°N. Five Souness GLFs are found in this field of view, and the HiRISE fields PSP_005663_2195 and ESP_027855_2195 are located overlapping or near to Souness GLFs.|
|Area at ~ 86°W, 44°N with several Souness GLFs.|
|An area somewhat further NE at 84-83°W, 45°N with several more Souness glacier-like forms. There is a HiRISE stereo pair with 3D anaglyph as well as two further HiRISE footprints in vicinity of GLFs.|
|An area further to the east in HRSC tiles h5401 and h5383 around 72°W, 48°N, showing several Souness GLFs and gullies. It shows that the classifier is not very specific to the Souness type valley glacier analogue objects, given that it shades many other areas as well.|
|At around 81°W, 49°N in HRSC tile h1528, a further example of the classifier shading a much broader range of terrain than that underlying Souness GLFs. The HiRISE images ESP_016752_2300 and ESP_024334_2300 overlap GLFs in this field. |
We turn again to the northern hemisphere of Mars, with the areas around Erebus Montes and north of Olympus Mons shown in this post.
Ultimately I'd like to work out a way to have zoomable images, I'm thinking of using something like Leaflet.js. For now I show a few areas of interest.
|The area to the north of Olympus Mons has a lobate debris apron believed to have formed through glacial processes at an earlier epoch than the Souness GLFs.|
|The elevation colour ramps, with one ramp used for the h0037 field, which also has some contrast/brightness adjustment in the nadir image tile, and the second colour ramp for all other fields shown above.|
Showing the elevation only, and a version blended with a hillshaded DTM:
Erebus Montes - tile h1258
|This area has a HiRISE anaglyph available. I have only noted anaglyphs in the vicinity of Souness objects published up to summer 2014, there may be others of interest, using JMARS, Google Earth or the HiRISE website you may find others.|
|With the classifier values, showing blue for 'extent' areas, and red for 'head' areas as usual|
|Further south in tile h1258|
|Close up of Souness 122 showing overlap with area covered by HiRISE anaglyph|
Acheron Fossae region
|The area to the north of Olympus Mons showing a number of Souness GLFs.|
|Ln(K) across this area.|
|Ln(K) for part of h1232 and h1210|
|Part of h0037|
|Close up of Souness 86 (head shown with the red circle) with overlapping HiRISE anaglyph footprint.|