Featured Image - 05/19/2009
Leveed Rille in Mare Cognitum
Large impact basins on the lunar nearside are filled in by lava flows.
Despite fact that about 16% of the Moon’s surface is covered by lunar maria
[Wilhelms, 1987], evidence of flow margins and flow fronts for these
lava flows is scarce [Schaber et al., 1976]. South of the Apollo 14
landing site in the Fra Mauro highlands is a very unique lunar rille
in Mare Cognitum adjacent to Craters Bonpland and Fra Mauro (Fig. 1).
This lunar rille is different because it has levees adjacent to the
channel (Fig. 2), whereas the majority of lunar sinuous rilles appear
carved directly into the lunar surface. Levees are constructed as
lava cools along the sides of the lava flow, creating a channel down
the middle of the flow for the lava to continue down. The lava can
overflow from the channel, splashing or flowing onto the levees,
making them thicker [Sparks et al., 1977; Harris et al., 2008; Glaze
et al., in press]. By measuring the dimensions of these levees, we can
learn more about the eruptions that formed them
and help distinguish why they are different from typical lunar rilles.
Figure 1. Young lunar lava flows in Mare
Cognitum embay ejecta from Craters Bonpland and Fra Mauro. Crater
rims are marked by the dashed white lines. Field of view of the
lava channel shown in Figure 2 is outlined by white box. (Apollo
Image AS16-M-1983 [NASA/JSC/Arizona State
The lunar maria may look homogenous with the naked eye from Earth, but
satellite data and samples from the Apollo missions indicate that they
are very different with respect to age, geochemistry, and even natural
surface color. The Lunar Reconnaissance Orbiter will obtain high-
resolution remote sensing data sets that will be used to characterize the
geochemical, spatial, and temporal differences between the lunar
maria. This information will be used to help select potential landing
sites for future human and robotic missions to the Moon. Knowing
where different types of lava flows are on the Moon allows lunar scientists to plan a
sampling strategy for future missions. These samples will provide
insight into the ages and geochemical properties of the lavas and also
tell us about their subsurface source regions.
Figure 2. (A) Close up of the lava channel. (B) The thick levees along the lava channel are marked by white arrows. (Apollo Image AS16-M-1983 [NASA/JSC/Arizona State
Glaze, L.S., Baloga, S.M., Garry, W.B., Fagents, S.A., and Parcheta,
C., A hybrid model for leveed lava flows: Implications for eruption
styles on Mars. Journal of Geophysical Research, in press.
Harris, A.J.L., Favalli, M., Mazzarini, F., and Hamilton, C.W., 2009,
Construction dynamics of a lava channel. Bulletin of Voclanology,
v. 71, p. 459-474.
Schaber, G.G., Boyce, J.M., and Moore, H.J., 1976, The scarcity of
mappable flow lobes on the lunar maria: Unique morphology of the
Imbrium flows. Proc Lunar Sci Conf 7th:2783-2800
Sparks, R.S.J., Pinkerton, H., and Hulme, G., 1976, Classification and
formation of lava levees on Mount Etna, Sicily. Geology, v. 4,
Wilhelms, D.E., 1987, The Geologic History of the Moon. USGS
Professional Paper 1348, 302p.