Monday 7 February 2011 - Stratified Ejecta Blocks (The Stripy Boulder Hunt!)

[jules]

Another hunt....and this time it's stripy!
Katie Joy from the Moon Zoo team says:

We would like you to take a closer look at large boulders in Moon Zoo images. We want people to spot boulders that have layers cutting across the rock. There are some examples of the features we are interested in this LROC post and in this fascinating Lunar and Planetary Science Conference abstract.


LROC article

Please look for layers that are as clearly spotted as those in the examples – ideally more than five obvious bands in the boulder (dark to light layers). Look at boulders that have rolled down slopes, those that are sitting in rubble-filled gullies and even boulders that are just sitting on their own. Please provide images of features you find and if you can state the location of the NAC frame where the boulder was found would be a big help.

Finding such boulders is really exciting as they suggest that large blocks of ‘bedrock’ are exposed and that could potentially be sampled by astronauts of robotic missions to the Moon. Lunar bedrock is normally hidden from view under a soil-like covering called regolith - the Apollo missions never sampled rocks from bedrock units (although layers of rock were seen from afar in the walls of Hadley Rille at Apollo 15 – see the astronaut’s comments at 165:23:26 available here!). Sampling bedrock layers that have a stratigraphic sequence (layers that have built up in a time-sequential manner) will provide unique information about how lunar rocks have formed with time. They will likely contain a temporal archive of lunar and Solar System processes (see this research about accessing a record of the Moon’s interaction with Space), and therefore are time capsules that provide a view to processes occurring millions, if not billions of years ago.

Happy stripy boulder hunting, and thank you once again for all your help,
Katie Joy

 
Well to kick things off, forum members Half65 and Tom128 found these examples of stratified bouders in Aristarchus. I think this is the type of boulder we should look out for as the LPI paper Katie links to shows some similar boulders in Aristarchus. Hopefully a team member will come along and comment. The NAC image is M111904494RE

[Geoff]

Interesting project - I'm currently hunting through images from Aristarchus for more stripey boulders.

[Tom128]

Love these treasure hunts. Great article Jules!

[Geoff]

My first results - these are the best I can find on this strip (but more strips to search!)

All images from: M114267211RC  (Aristarchus region)


1/3 of the way from the top of the strip.


1/4 of the way from the top of the strip.


1/3 of the way from the top of the strip on the right-hand edge.

[jules]

Great start! One of the papers Katie refers to is about stratified rocks in Aristarchus so it looks like these are more examples of those. Be nice to find some elsewhere too.

[Geoff]

A couple more images from Aristarchus region.

These are from strip: M114267211LC


This image is about 1/3 from the top of the strip on the left.


About a 1/4 of the way from the top of the strip, in the centre.

[kjoy]

Geoff those lower images are great examples of stratified boulders around Aristarchus - this is exactly what to keep an eye for in other images. I am not sure that the middle set of images (time 12:07:48) are probably convincing enough - however, the top two examples from Jules's selection look pretty good as well (certainly the top right one).

Thanks for hunting!

Katie 

[Tom128]

I found this interesting boulder (large one center) that may be stratified though it does look like a mix of rock and other regolith. Interesting none the less.  Some boulders around the crater seem to look stratified but the too close to call.

http://wms.lroc.asu.edu/lroc/view_lroc/LRO-L-LROC-2-EDR-V1.0/M119850269LE 

52.51 N and .23 W

[eshafto]

ID: AMZ1000zau
Latitude: 24.3843°
Longitude: 312.728°
http://www.moonzoo.org/examine/AMZ1000zau

All the way to the left, about half-way down, appears to have stripes running from our right to left (or vice versa, if your mind tends to such things).

Funny, I didn't notice that the entire middle of the picture is taken up with a giant crater until I went to post the image here.

[eshafto]

ID: AMZ10035xy
Latitude: 23.5862°
Longitude: 312.466°
Sun Angle: -75.86°
Scale: 0.50 meters / pixel
http://www.moonzoo.org/examine/AMZ10035xy

Lots of stripes! The big boulder just above the center, the two sticking out about 1/5th from the left and 1/3 from the bottom, and a couple of others, possibly.

[jules]

Thanks eshafto - Aristarchus is definitely a good hunting ground for these stripes!

[ElisabethB]

AMZ40042ss
Latitude: 23.567°
Longitude: 312.443°
Sun Angle: -75.86°
Scale: 0.50 meters / pixel

[eshafto]

Yeah, stripes are old news, but I liked this one:

ID: AMZ1002g9m
Latitude: 24.0753°
Longitude: 312.983°
Sun Angle: -55.08°
Scale: 0.51 meters / pixel
Zoom Level: 3

Lots of cool stuff, including stripes at 1,1 and 4,4, and where it looks like a slide split around a boulder in 3,1.

[astrostu]

I actually met the guy who originally solicited this request from Katie Joy.  Turns out I had been at a field camp with him at Meteor Crater in Arizona.

[jaroslavp]

Yeah, stripes are old news, but I liked this one:

I like the top left one looking like a small pyramid.