A Field Guide To Lunar “Black Stuff”
This week forum regular kodemunkey has chosen to highlight the lunar “black stuff” we have been looking for since Dr Tony Cook asked us to post examples. Often difficult to distinguish from shadows this black deposit might be volcanic in origin or just a dark albedo feature. Whatever it is we now have quite a collection to study. Over to kodemunkey to explain further.
Hello once again moon fans, this week I have a strange one for you, Lunar “Black Stuff.”
Of all the sub-topics on the forum, I think this one is the most mysterious and it’s certainly caught my attention.
To quote Anthony Cook on the subject:
“Description: Dark slightly branching features, often on the shaded side of slopes. Boulders associated with these. Also appears as an exposed strata layer in a nearby rill rim.
Interest: Is this “dark stuff” an exposed dark material black volcanic glass, a deep branching crack with shadow, dark boulders, or a combination? Either way we need to find more of these and their geographical distribution. Could be worth monitoring these from orbit and at different sun angles to see if the darkness is related to shadow.”
I, like many people, enjoy both a good mystery and a chance to be nosey, so this was one project that suited me down to the ground (or regolith if you prefer!)
(Obsidian)
Where has it been found so far?
During my time on the forum, I’ve found examples of “Black stuff” in the following locations:
Marius Hills (Perhaps ejecta from Aristarchus / Kepler?)
Schroter, Fauth, Bode, Sommering and Gambart (Ejecta from Copernicus perhaps?)
Vallis Alpes.
As well as various dark haloed craters and other unnamed crater ejecta blankets.
This section is a guide to where you might find examples of Black stuff:
On the edges of rille systems
Vallis Alpes Rille
Rimae Marius
On crater rims
Unamed impact, Taurus-Littrow region
Crater floors
Unnamed far side impact
Occasionally in the ejecta blankets of small impacts
Minor impact within Michelson crater on the far side.
Unnamed near side impact
Covering the landscape
Marius Region
Schroter Region
Question time:
Taking into account the number of impacts, both large and small, why isn’t there more black stuff laying around, and why is it seemingly more prevalent on the near side more than the far side?
Sources used:
WMS Browser: http://wms.lroc.asu.edu/lroc#damoon
Act – React tool: http://target.lroc.asu.edu/da/qmap.html
Moon Zoo Thread “TLP – Black Stuff”: http://forum.moonzoo.org/index.php?topic=264.0
Special mentions go to forum moderators Jules, Geoff, Ireneant and forum members Astrostu and Tom128, who i imagine i drove to insanity badgering them with my own inane ramblings on the subject.
Into the lake of death!
The ‘Lake of Death’ (Lacus Mortis) lies in the northeastern part of the Moon, north of Mare Serenitatis, and is either an ancient crater or a basin, which has been flooded by lava. It is about 150 km in diameter with the crater Burg, which was formed less than a million years ago, situated approximately in the centre. Lacus Mortis was named by selenographer Giovanni Riccioli in 1651 but he gave no reason for its strange name.
Lacus Mortis also contains one of the few “true” faults found on the Moon and you can see it (marked with an orange arrow) in the image below starting at the southern boundary of Lacus Mortis and going north before finally turning into a rille. (See the first link under Useful Links for more images of the fault).
The western half of Lacus Mortis also contains several rilles, the main one of which is Rimae Burg which is over a 100 km in length and is a graben. Where this rille crosses the boundary between Lacus Mortis and the highlands in the southwest, there are some volcanic cones – see link #4 under Useful Links for more information.
[ACT-REACT Image]
A larger image containing feature names will be found here: LROC Context Image
Burg crater, within Lacus Mortis, is worth exploring as it has many boulder tracks and some nice landslide textures on the western crater wall. See links #2 and #3 under Useful Links for more information.
Strip: M113778346LE
Boulder tracks within Burg crater
Landslide textures from inner wall of Burg crater, western side.
Useful Links
A true fault in Lacus Mortis: Lacus Mortis Fault
Boulder tracks within Burg crater: A Gathering in Lacus Mortis
Description of Burg crater: Not your average complex crater
Volcanic domes: Volcanoes in the Lake of Death
A mystery! Tidbits of Strangeness
Moon Zoo 