Thursday, December 20, 2012

Superposition: 'Crater on Crater on Crater'

A small unnamed crater sits on the rim of a larger crater which, in turn, is itself nested on the rim of farside pre-Nectarian crater Buisson. LROC Narrow Angle Camera (NAC) observation M1107532088RE, spacecraft orbit 15502, November 14, 2012; field of view roughly 1000 meters, resolution 1.05 meters per pixel [NASA/GSFC/Arizona State University].
Drew Enns
LROC News System

The law of superposition is one of the earliest geologic laws, based on the observations of Danish scientist Nicholas Steno.

Originally formulated to describe relative ages of sedimentary rock units, the law of superposition works just as well on the Moon to describe relative age relationships of separate lunar terrains and craters.

What are the relative ages of the different craters in today's Featured Image?

LROC Wide Angle Camera (WAC) mosaic of Buisson, context for the field of view above, showing the small crater at high resolution above (red box). Additionally, a relatively small crater sits on the rim of ancient Buisson, located at 1.42°S, 112.96°E. Field of view 100 km [NASA/GSFC/Arizona State University].
In today's Featured Image, we have three separate craters. Buisson crater is the largest at 57 km, with an approximately 4 km wide unnamed crater on its rim. 

Zooming in further, we see an even smaller crater, about 110 meters wide, in the 4 km crater rim. The superposition of these craters gives us a relative age relationship with the 110 m crater the youngest, followed by the 4 km crater, and finally Buisson crater.

Explore more of crater relationships in the full LROC NAC, HERE.

Related Posts:

No comments: