The current theory of the moons formation is that it was formed when the Earth was hit by a Mars sized planet. This caused the earth’s tilt and the faster rotation of the earth which is now slowing at a rate of 2 seconds for every 100,000 years. Shortly after the moon was formed it was about 200,000 miles closer to the Earth than it is today. That means that the tides were actually more like mega-tsunami’s.

(The Great Courses – A New History of Life)