July 16, 2013
Backside Plateau Slide
left image by Jocelyn Sérot, France, and right topo map from LRO QuickMap.
While observing the Moon tonight (July 15) I noticed one place in the backslope of the Apennine Mountains that was casting a much more conspicuous shadow than any other mountain except those along the front. What is that unusually tall, compared to its neighbors, peak doing there? Looking through past LPODs - the source for the best images of the Moon - I came across this view on the left (part of Jocelyn's LPOD of May 6, 2009) that nicely shows the peak. The piece of the topographic map from the LRO QuickMap at right reveals that the height difference of the peak, actually more of a plateau, is big enough to show up as an island of elevated gold in a sea of green. A topographic profile shows that the plateau is about 1800 m above the adjacent terrain to the west. The plateau is near the barely visible (but I did see at the telescope the curved partial rim that qualifies it to be a crater) Marco Polo (MP), but doesn't seem related. I also observed the black pit of Marco Polo L that is unrelated too but neat to see. Comparing the topo map and the image I can imagine that the plateau is near the right side of an ancient 70-75 km wide crater. That may explain the roughly circular depression about 1 km deep, but still doesn't explain the peak. I suppose that since high elevations of the Apennines are pretty much limited to the front of the range, that the plateau slid down from an originally higher position near the Apennine front. In fact, looking carefully at Jocelyn's image you can see ridges of material that parallel the ridge and look like rolls of debris that followed the plateau down the backside.
21st Century Atlas chart 18.
A lower Sun view
Yesterday's LPOD: Polar Crater Hopping
Tomorrow's LPOD: One More Medal