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The accompanying image shows the highlands -mare contact at the eastern edge of Mare Nubium.  The NW-SE trending lineaments in the highlands are "Imbrium Sculpture" formed by scouring from Imbrium Basin impact ejecta about 3.85 Ga ago. This area is roughly 700 km south- southeast of the Apennine Mountains, which marks the southeast edge of the Imbrium Basin.
 
 

Q1 (2 pts). What are the relative ages (from oldest to youngest) of crater formation for Craters D, Y, and 1?  How can you tell?
 
 
 

Q2 (2 pts). Which is older, the surface of Unit 2 or Mare Nubium?  How can you tell?
 
 
 

Q3 (2 pts). Which is younger, the formation of Crater D, or the eruption of basalts in Mare Nubium?  How can you tell?
 
 
 

Q4 (2 pts). Which is older, the formation of Crater 3 or Imbrium Sculpture?  How can you tell?  (HINT: Look at the rim of Crater 3.)
 
 
 

Q5 (2 pts). Which is younger, the formation of Crater Y or Imbrium Sculpture?  How can you tell?
 
 
 

Q6 (2 pts). Based on crater densities, what is the relative age sequence (from oldest to youngest) of the floor of Crater 3, the light-colored floor of Crater Y, the surface of Mare Nubium, and the surface of Unit 2? If ages for any two or more of these are about the same, indicate this.
 
 
 

Q7 (5 pts). Using your answers to the questions above, construct two stratigraphy columns placing older deposits below younger for the following: (a) crater ejecta from craters D, Y, 1, 3, and Imbrium; (b) the plains in Mare Nubium, the plains in Unit 2, the plains in the floor of Crater 3, the light-colored plains in the floor of Crater Y. If ages for two or more of these in either (a) or (b) are the same, or you are uncertain about the relative ages of any feature, put them in the same vertical position in the stratigraphy column.
 

Column a: ejecta deposits                                          Column b: plains deposits
 
 
 
 
 
 
 
 
 
 
 
 
 

Q8 (3 pts). Label each vertical position in your stratigraphy columns in Q7 by absolute age, according to whether the deposits are 3.85 Ga old, >3.85 Ga old, or <3.85 Ga old.
 
 
 

Q9 (2 pts). If you were told that the light-colored floor plains of Craters Y and 3 formed partly as fluidized ejecta from the Imbrium impact, would it change your assignment of absolute ages in Q8? In what way?
 
 
 

Q10 (4 pts). The Davy Crater Chain extends for about 50 km across the floor of Crater Y and up the eastern wall of this crater onto the surrounding highlands. It was a candidate Apollo landing site. Two hypotheses were proposed at the time to account for the origin of the chain (another was proposed after the impact of comet Shoemaker-Levy 9 on Jupiter). Using the clues provided here and in the image, and your knowledge of cratering processes on the Moon, list two different hypotheses for the origin of the chain and your rationale.