Ages
The ages of the mare basalts have been determined both by direct physical dating and by the technique of crater counting. The radiometric ages range from about 3.16 to 4.2 Ga, whereas the youngest ages determined from crater counting are about 1.2 Ga (1 Ga = 1 billion years old). Nevertheless, the majority of mare basalts appear to have erupted between about 3 and 3.5 Ga. The few basaltic eruptions that occurred on the far side are old, whereas the youngest flows are found within Oceanus Procellarum on the nearside. While many of the basalts either erupted within, or flowed into, low lying impact basins, the largest expanse of volcanic units, Oceanus Procellarum, does not correspond to any known impact basin.
Read more about this topic: Lunar Mare
Famous quotes containing the word ages:
“The gods are partial to no era, but steadily shines their light in the heavens, while the eye of the beholder is turned to stone. There was but the sun and the eye from the first. The ages have not added a new ray to the one, nor altered a fibre of the other.”
—Henry David Thoreau (18171862)
“All for me? And not a question
For the faded flowers gay
That could take me from beside you
For the ages of a day?”
—Robert Frost (18741963)
“What distinguishes modern art from the art of other ages is criticism.”
—Octavio Paz (b. 1914)