Aviezer doesn't concern himself with creation except where the shoresh "bara" appears. The rest are the "big events" that brought the earth to its current state. So acc. to Aviezer-
Day 3= The Permian Ice Age where the waters of the flooded earth glaciated in the South Pole causing the oceans to recede. Later during this period was the proliferation of modern plant life.
Day 4= The point at which the Earth's eccentricity, axial obliquity and season of perihelion (in relation to the sun) aligned to allow a 24 hour day, 365+ day year and today's seasons (about 10,000 years before present, which is what also ended the most recent ice age). These changes are caused by the moons gravitational "pull".