The fourth aliyah continues with Lot's escape from Sodom. As Lot is escaping, his wife looks back and becomes a pillar of salt.
Eventually, Lot and his two daughters take shelter in a cave. The two daughters think the whole world is destroyed as with the flood at the time of Noach, so they decide that they need to re-populate the world through their father.
At the end of this aliyah Avrohom's wife Sarah conceives, and gives birth to a son. Avrohom performs a bris mila on him when he is 8 days old, and names him Yitzchak.