Freundlich

D=85 km
Center: 25¡N, 171¡E

Count Area: 1862 km^2
Observed Density (@ 1km): 32800 ± 4200
Age: 4.0 ± 0.1 (+sec: 4.1)
Stoffler epoch: Pre-Nectarian
Fit density (@ 1km): 44600 ± 7000
PF fit: good*, large craters are shallow, but only a few need to be "removed" to get a good fit


Age calculation notes:
- fit anchored at large D. good fit achieved with layering. thickness H=0.33km. the top layer has Y=2e7, the bottom layer has Y=2e8 (SM).
- good fit for large D - bad fit for small D - maybe geology - but try strength scaling law or layer?; adding OSs doesn't change fit or age. fit improved to good using layering (LrN), age decreased (MRK).
- why does using layering work? Including a change in strength causes the PF to kink and shift for small D (transition occurs D ~ 1.5 km), which is why the fit is better. But is there justification for using this law here and not with other craters (i.e., is geology different)? The surface does have a weathered look, but can see small areas that look more "solid". There are partially filled larger craters indicating a slightly thicker layer of fill (which we see on other craters without this kink). So a semi-thin "weak" layer over a stronger layer is not unreasonable. Note a resurfacing event that removes small craters preferentially can produce the same effect and terrains of two ages. Although a region of of lower small crater density does not pop out. (MRK)

USGS geology: 
Crater mapped as Nectarian. Small areas of floor material mapped as fill with Imbrian age.

Wilhelms: 
Nectarian (all materials)

Floor material: 
Best guess is not original on east side (west side is unknown). Flatter floor, material has contacts with wall that look embayed, fill in larger crater on the floor, small central peak. Material looks softened. Loose?

Geology Observations: 
Ejecta not visible. Rim is eroded, but has a little sharpness. Small central peak that looks heavily eroded. Floor has low hummocks with some smooth areas. Possible dichotomy between east and west sides. A few secondary chains/clusters with various sized craters (up to ~ 1.6 km) - mostly degraded.

SFD Observations: 
Craters < ~ 1.5 km dominated by class 4. Largest craters dominated by class 3. Classes 1 and 2 lower in density. Has flat SFD for full diameter range. Slope(Diff)=2.7 ± 0.2.

Discussion notes: 
no issues

Notes from Brian's adjustment:
- Counting boundary:
	Looks good.
	Maybe a small concern with some rim included in SW - decided not to change (MRK).
	Some type 4's were missed, both large and small.

- Secondaries:
	Marked pretty well. Not sure if the large craters near 5:00 are
secondaries, but they could be.

- Removal of large, buried craters:
	Three large "secondaries" near 4:30 might be buried craters??

- Size adjustment of large craters:
	No adjustments needed.

- Explaining unusual cases:
	Freundlich marked in red, comment "no shallow."
	Quite a few large craters (but most are secondaries).

- Future actions:
	Perhaps remove the three possible-buried craters?

- Completed actions:
	Readded some missing type 4's and large secondary craters (BLE).
	Reassigned a classes on a few craters. (MRK)
	Removed some partially buried craters in the SE. (MRK)

Last Edited by MRK 11/18/2012