Arnold

D= 93 km
Center: 67°N, 36°E

Count Area: 4567 km^2
Observed Density (@ 1km): 19500 ± 2100
Age: 3.8 ± 0.1 (+sec: 3.8)
Stoffler epoch: Early Imbrian
Fit density (@ 1km): 17300 ± 2600
MPF fit: good, data is slightly steeper

Age calculation notes:
~ good fit (SM).
Mostly good fit - first and last points off the line (this is a "right ear" crater) - also trend is slightly steeper - use as is; adding OSs does not change fit or age (MRK).

USGS geology: 
Crater rim material mapped as Imbrian to Pre-Nectarian. Floor material mapped as fill with Late Imbrian age.

Wilhelms: 
Rim is Pre-Nectarian. Floor is Imbrian fill - possibly Imbrium ejecta(?).

Floor material: 
Best guess is not original. Very smooth, flat floor, surrounded by other filled craters and mare, and no peak visible. Plus see flow fronts/wrinkle ridges. Looks fresh. Hard?

Geology Observations: 
Maybe small section of ejecta visible near rim (confusing?). No central peak. Floor flat. Several secondary clusters and chains observed of various sizes (up to ~2.7 km) and degradation states. 

SFD Observations: 
Small craters (< 1.5 km) dominated by class 3, one large craters dominated by class 1. Steeper distribution for small craters (D < 1.5 km), shallow for large. Shallow "right ear" (although only composed of one crater). Slope(Diff) = 5.3 ± 0.4

Additional Note: 
This crater was used to compare counts from different counters: Michelle, Kristen, and Brian.

Discussion notes: 
Data is slightly steeper than fit, move fit to fit small points better. fill is likely mare.

Last Edited by MRK 11/15/2012