Revealed Surface

Southern slope of unnamed fracture along the eastern mare/highland boundary of Mare Insularum. LROC NAC M1114199297R. Image center is 13.135°N, 355.638°E, image width is 1147.2 m. Downslope is toward upper-right, north is to the top [NASA/GSFC/Arizona State University]. 

Today's Featured Image highlights a portion of an unnamed linear fissure located along the eastern edge of Mare Insularum, near the mare/highland boundary. The width of this fissure varies from about 1.5 to 2 km, its  length is about 90 km, and it extends in the northwest-southeast direction. The upper-right portion of the opening image, showing a shallow groove extending from up to middle right of the image, corresponds to the bottom of the fissure. Thus most of the image reveals the southern wall of the fissure. 

On this slope, there is a high reflectance area with sinuous boundaries. This unit is hard to interpret in terms of what is on top and what is below, stratigraphically. The sunlight is from left side, highlighting what appears as a slightly raised boundary between the two units (arrows). Elsewhere it looks as if the high reflectance material overlies the lower reflectance material. Which unit is younger? Try counting craters between the two, but be careful, if the units have different hardnesses, then the more coherent unit may preserve craters better. 

Unnamed fracture and surrounding areas in LROC WAC monochrome mosaic (100 m/pix). Image center is 6.57°N, 177.82°E. NAC footprint (blue box) and the location of opening image (yellow arrow) are indicated [NASA/GSFC/Arizona State University]. 

Since this whole area is on a slope, slope failure may have revealed an underlying immature surface. Indeed multiple higher reflectance boulders are sitting at the downslope side of this high reflectance unit. But the upper complicated shapes are difficult to explain by this simple story. Or perhaps low reflectance materials could have slumped and covered portions of the high reflectance material? A high resolution NAC DTM would help scientist unravel this complicated morphology. 

Explore this enigmatic patterned surface in full NAC frame yourself!

Related posts:

Inside Hyginus CraterBright ridge near Mons HansteenWrinkle Ridge vs. Impact CraterReally WrinkledBoulders In The Sea Of SerenityGhost crater in Mare ImbriumZebra StripesAitken Central Peak, Seen ObliquelyConstellation Region of Interest at Mare Tranquillitatis 

Published by Hiroyuki Sato on 13 June 2013