Dorsum Nicol

LROC NAC with colorized slope overlaid.
This tectonic feature was formed as stresses built up in the lunar crust until the rock gave way. The energy released was immense, and the displaced rock is the north-south trending wrinkle ridge that we see today. This is LROC NAC image M1105773947LR with a slope map overlaid, warmer colors in the image represent steeper slopes. Image is 4765 m wide; north is up [NASA/GSFC/Arizona State University].

Dorsum Nicol is a wrinkle ridge found in southern Mare Serenitatis. The opening Featured Image is an LROC NAC image overlaid with a slope map of the region, with warmer colors representing steeper slopes. Slope maps are useful to planetary scientists because topographic features like craters and small ridges really stand out. At the Featured Image location, the mare on the west side of the ridge is ~100 m higher in elevation than the mare on east side of the wrinkle ridge, and the peak of the ridge is ~50 m above that (see profile below).

Elevation profile of the Dorsum Nicol wrinkle ridge.
Elevation profile across Dorsum Nicol at the Featured Image location. Points A and B correspond to A and B in the context image below.

The difference in elevation between the eastern and western flanks of the ridge could be due to the lunar crust buckling and folding beneath the surface, or it could be from mare fill after the wrinkle ridge was formed.  Dorsum Nicol has a width of 10 km at its widest, and 5 km at its narrowest. Take a look at the full feature in the context image below.

Annotated LROC Context image

LROC WAC context image of Dorsum Nicol in Mare Serenitatis. The yellow box is the approximate location of today's Featured Image, the red box is the location of the full NAC DTM, and a profile was taken along the white line from A to B and is shown above. Image width is ~100 km; north is up  [NASA/GSFC/Arizona State University].

Wrinkle ridges are are surface expressions of compressional forces being released; they are seen in all large maria on the Moon. The loading from the massive flood basalts during mare volcanism could have caused the lithosphere to flex, because the density of the flood basalts is higher than the anothositic highlands material. Buoyancy forces were at work here, causing viscoelastic relaxation and inducing forces in the mare rock.

These forces caused the once convex surface of the maria to become more planar as time went on. This is a problem because a plane has less area than a curved surface when they are bounded by the same radius. Where was the rock going to go? Well, the maria resisted this change in topology until something broke! Wrinkle ridges are the expression of that thrust fault behavior.

Check out the full NAC frame below, or download the DTM from our product page!

Related Posts:

Really Wrinkled

Wrinkled, But How Old?

Wrinkle ridges of northwest Mare Imbrium.


Published by Aaron Boyd on 17 July 2014