Major Lunar Maria
| 1. Oceanus Procellarum |
2. Mare Imbrium |
3. Mare Cognitum |
4. Mare Humorum |
| 5. Mare Nubium |
6. Mare Frigoris |
7. Mare Serenitatis |
8. Mare Vaporum |
| 9. Mare Tranquillitatis |
10. Mare Nectaris |
11. Mare Humboldtianum |
12. Mare Crisium |
| 13. Mare Fecunditatis |
14. Mare Marginis |
15. Mare Smythii |
16. Mare Australe |
| 17. Mare Moscoviense |
18. Mare Ingenii |
19. Mare Orientale |
Shown here is a map of the major lunar maria. These maria range from over
200 km to about 1200 km in size. They are typically about 500 m to 1500 m
thick. However, each mare appears to contain many thinner basalt flows.
Typical flow thicknesses appear to be
10-20 m. Thus, each mare records hundreds of overlapping eruption events.
The map also shows a clear lack of major maria on the lunar farside. This
probably reflects two changes in the lunar crust. First, the lunar surface
is higher on farside than on the nearside. Second, the crust seems to be
thicker on the lunar farside than on the nearside. These differences
should make it harder for mare magmas to reach the surface on the lunar
farside. They also explain why small mare patches are grouped together on
the farside. The mare patches represent lava-filled craters. Most such
craters lie in the bottoms of much larger and much older basins. On the
nearside, such basins contain circular mare. On
the farside, such basin filling volcanism is rare. Still, these basins
contain both the lowest surfaces and the thinnest crust. Thus, mare
volcanism is most likely inside these basins, especially where younger
craters have dug into the basin floor. (Map prepared by G.W. Colton;
published in NASA SP-362 (1978) and NASA SP-469 (1984).)