Date and time: 30 April 2012, 1100 to 1700 hrs
Written by: Ali Harley, Crew 118, MSPS
Time: 1900 hrs
Hari Mogosanu, Annalea Beattie, Don Stewart, Ali Harley
Primary site - Muddy Creek - elev. 1384 12S 0508581 UTM 4264613
Pressurised Rover and on foot
Compare Muddy Creek gravels with Cow Dung Road Cattle Grid gravels (already collected on EVA 01)
Rivers act as sampling mechanisms across large area, studying their sediments provides both average and specific geological and geochemical information for much larger areas than can be otherwise obtained for a single site.
The Mars Pathfinder targeted in the outwash area of Ares Vallis because the deposits were expected to contain a range of rocks from further upstream. The rocks were examined by the Pathfinder camera and the camera and APX onboard the Sojourner rover. A diversity of rocks was observed, consistent with fluvial transport and mixing, confirmed by the evidence of boulder imbrication.
On Earth mineral explorers and environmental scientists use stream sediment sampling (focusing on sediment mineralogy and chemistry) to look for mineral deposits or sources of contamination upstream. One single sample can characterise an entire subcatchment.
1) understanding on how rivers collect sediments across their catchments and export them.
2) Works on Earth and Mars - universality of physical processes
We visited Muddy Creek via Factory Bench - elev. 1430 12s 0508255 UTM 4257618
and the San Raphael Swell (?) - elev. 1450 12s 0505430 UTM 4260801.
On Factory Bench we stopped at an outcrop that contained coal and gypsum.
The gypsum is approx 1/4 inch thick and was continuous in more than one layer.
Don took a sample of the coalish layer (which has a yellow coating on it) and we think we can see tiny amber specks inside.
Also inside is some tiny fine white filamentous mineral. On the road approx 1 mile back at a sandstone outcrop (and campsite) we found a little piece of what we think is volcanic glass (browny black in colour and melted onto the sandstone). Plus some chert conglomerate. There were more oyster shells up on Factory Bench, some in matrix.
At the south end of San Raphael Swell (?) we found some tiny bivalves and a tiny gastropod (tbc) in the shale.
At Muddy Creek we collected 100 pebbles to complete the gravel experiment. The first noticeable thing about the gravel was that, compared with the gravel at Cow Dung Road, it is smooth (round or flat). We saw one brecciated conglomerate.
Keep a watchful eye while in Utah! - at Muddy Creek we saw big cat paw prints leading down to the river. They were about the size of a woman's palm.