MSL Science Team Field Site Discussions — Eberswalde CraterEdgett, p. 1 Eberswalde Crater MSL Candidate Field Site in Context by K. Edgett, 9 June 2010 drainage basin (and lake beds?) overlying Holden ejecta “delta” Holden ejecta Holden north rim

A Brief History of Eberswalde Region Recall from the 19 May 2010 Holden telecon I gave a brief summary of the pre-Holden setting (see next page for illustration) –Giant multi-ringed basin, “Ladon Basin,” formed Modification (erosion, in-filling, further cratering) then got underway –Smaller multi-ringed basin, “Holden Basin,” formed Modification (erosion, in-filling, further cratering) then got underway –Eberswalde Crater formed Modification (erosion, in-filling, further cratering) then got underway –Holden Crater formed and ejecta went into Eberswalde After Holden formed, more stuff happened (also discussed at 19 May telecon) –Deposition and lithification of light-toned, layered sediment in Holden –Cutting of that sediment by flood(s) from Uzboi Vallis –Deposition of fans in Holden –All subsequent modifications (erosion, further cratering, further sedimentation, etc). –No clear evidence for volcanism in the region (but, in my experience, that doesn’t mean none happened) Lots of other things happened outside of Holden, including in Eberswalde –Fluvial erosion, sedimentation, formed lake(?) on Holden ejecta to immediate west of Eberswalde The sediment later becomes lithified and then eroded to its present form/expression –Fluvial erosion, sedimentation, forms the delta in Eberswalde (and perhaps a lake) –Other light-toned layered materials were deposited and lithified in depressions on Holden’s ejecta blanket and in Holden’s secondary craters –Later weathering and erosion (or little green persons) dis-integrated and removed considerable sedimentary rock from Eberswalde and the delta, leaving the delta channels inverted and few (if any) lake sediments MSL Science Team Field Site Discussions — Eberswalde CraterEdgett, p. 2

Eberswalde post-dates 2 large impact basins, pre-dates Holden Crater, and has Holden ejecta in it MSL Science Team Field Site Discussions — Eberswalde CraterEdgett, p. 3 Notes: See the viewgraphs I presented to the MSL Science Team on 19 May In there, I step through the sequence of events summarized here. 1)A large, multi-ringed impact basin (informally named “Ladon Basin”) formed. 2)While “Ladon Basin” was undergoing modification(erosion, in- filling, and cratering), a new, smaller multi-ringed basin formed (informally named “Holden Basin”). 3)Some time later, one of the many craters that superposed the eroding and in-filling “Holden Basin” was Eberswalde. 4)Still later, Holden Crater formed and some of its ejecta went into Eberswalde. 5)Even later, Uzboi Vallis entered Holden and there was a catastrophic flood. 6)Meanwhile, the delta in Eberswalde was forming. Notes: Where it occurs in Eberswalde, the Holden Crater ejecta blanket would likely include materials disrupted by the Eberswalde impact and materials deposited in the earlier “Holden Basin”. As you will see in Melissa Rice’s presentation today, MSL would have access to this material in the Eberswalde landing ellipse..

Some Features in the Eberswalde Region MSL Science Team Field Site Discussions — Eberswalde CraterEdgett, p. 4 CTX image on p. 6 (light-toned layered rock) HiRISE image on p. 6 (light-toned layered rock) EBERSWALDE HOLDEN “Holden Basin” ring mountains Holden secondary craters Ladon Vallis deepest part of “Holden Basin” light-toned rock Notes A few places where light-toned layered rock outcrops occur outside of Eberswalde and Holden are indicated (this is not all-inclusive). Eberswalde formed before Holden. After Holden formed, Mars was still the kind of place where “sediment” could be deposited and become lithified and further eroded. Such light-toned “sedimentary rocks” occur in some of Holden’s secondary craters and in depressions on its ejecta blanket. The “delta” in Eberswalde formed after the Holden impact occurred.

Much is Missing from Eberswalde MSL Science Team Field Site Discussions — Eberswalde CraterEdgett, p. 5 It is important to remember: 1)The channels in the “delta” are inverted. Material has been removed. 2)The same is true across the entire Eberswalde crater depositional basin. 3)How rocks are dis-integrated and transported out of a hole in the ground is a concern as well as a common theme across the planet. Gale and Holden present this problem, too. 4)It is an important part of the Eberswalde story: Some of what we are looking for (e.g., lake sediments) may have left the scene long ago.

SOME EXTRA STUFF MSL Science Team Field Site Discussions — Eberswalde CraterEdgett, p. 6 HiRISE PSP_003222_1565 CTX B18_016777_1580_XN_22S034W These figures— see locations on p. 4. These are examples of light-toned, layered-rock outcrops in region near Eberswalde. These post-date the Holden Crater-forming impact.