The Dawn Era is that period before the beginning of mortal time, when the feats of the gods take place. The Dawn Era ends with the exodus of the gods and magic from the World at the founding of the Adamantine Tower.
The term 'Merethic' comes from the Nordic, literally, "Era of the Elves." The Merethic Era is the prehistoric time after the exodus of the gods and magic from the World at the founding of the Adamantine Tower and before the arrival of Ysgramor the Nord in Tamriel.
The following are the most notable events of the Dawn Era, presented roughly in sequence as it must be understaoo by creatures of time such as ourselves.
The Cosmos formed from the Aurbis [chaos, or totality] by Anu and Padomay. Akatosh (Auriel) formed and Time began. The Gods (et'Ada) formed. Lorkhan convinced - or tricked - the Gods into creating the mortal plane, Nirn. The mortal plane was at this point highly magical and dangerous. As the Gods walked, the physical make-up of the mortal plane and even the timeless continuity of existence itself became unstable.
When Magic (Magnus), architect of the plans for the mortal world, decided to terminate the project, the Gods convened at the Adamantine Tower, Direnni Tower, the oldest known structure in Tamriel] and decided what to do. Most left when Magic did. Others sacrificed themselves into other forms so that they might Stay (the Ehlnofey). Lorkhan was condemned by the Gods to exile in the mortal realms, and his heart was torn out and cast from the Tower. Where it landed, a Volcano formed. With Magic (in the Mythic Sense) gone, the Cosmos stabilized. Elven history, finally linear, began (ME2500).— Aicantar of Shimerene, Before the Ages of Man