Ordering exercise: CONTEST
Inspired to give those Californians a run for their money with their cool examples of relative dating exercises, I took this photo last week down at Chain Bridge Flats, the westernmost corner of Washington, DC:
Your assignment, should you choose to accept it: tell me the geologic history of this boulder, in correct chronological order. To make it easier for you, I've labeled the relevant rock units with letters here. (The letters were chosen randomly, and do not by their alphabetic nature imply any sort of order. Note that "F" is the fracture surface defining the planar outer edge of the boulder.) First person to post the correct sequence of events in the comments area below wins a GEOLOGY ROCKS bumper sticker.
Answer in a couple of days. Good luck!
Your assignment, should you choose to accept it: tell me the geologic history of this boulder, in correct chronological order. To make it easier for you, I've labeled the relevant rock units with letters here. (The letters were chosen randomly, and do not by their alphabetic nature imply any sort of order. Note that "F" is the fracture surface defining the planar outer edge of the boulder.) First person to post the correct sequence of events in the comments area below wins a GEOLOGY ROCKS bumper sticker.
Answer in a couple of days. Good luck!
Labels: contest, dc, geologic time, piedmont
3 Comments:
My amateur reasoning has lead me to this time line-
D -> R -> X -> M -> F
This little quiz has reminded me of what I learned on the DC walk.
If it wasn't for this challenge - I might have forgotten.
xdrmf
thomas donlon
D -> R -> M -> X -> F
Although I'm least confident about the X-F order (choosing X -> F since the F surface seems smooth, and the one "x" near it seems to be cut by F)
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