Original: Nevertheless , some argue that the lunar sample data do not require a cataclysmic cratering event near 3.9 Ga , and that the apparent clustering of impact melt ages near this time is an artifact of sampling material affected by a single large impact basin .
Simplified: Some argue that the lunar sample data do not require a cataclysmic cratering event near 3.9 Ga. . They think the apparent clustering of impact melt ages near this time is an artifact of sampling .