Must have missed that one. What evidence?
My source is on page 195 of "Darwin's Ghost" (subtitled "The Origin of the Species, updated") by Steve Jones.
There, in a chapter titled "On the imperfection of the Geological Record," Jones writes:
"We live not a hundred million but four thousand five hundred million years since the Earth was spun from dust and rock around the sun. The evidence comes not from our own planet, but from its satellite. The Moon flew off its parent after a giant impact. Because it stayed small, cold and undisturbed it gives a better picture of the past than does its parent. A quick trip by the Apollo XI mission was enough to date it. The Earth's turmoil makes it harder to trace its own origin. Its oldest rocks, found in Greenland and Western Australia, are just under four billion years old."
http://starchild.gsfc.nasa.gov/docs/StarChild/shadow/question38.html
From that source we have ...
“In the mid-1970s, scientists proposed the giant impact scenario for the formation of the Moon. The idea was that an off-center impact of a roughly Mars-sized body with a young Earth could provide Earth with its fast initial spin, and eject enough debris into orbit to form the Moon. If the ejected material came primarily from the mantles of the Earth and the impactor, the lack of a sizeable lunar core was easily understood, and the energy of the impact could account for the extra heating of lunar material required by analysis of lunar rock samples obtained by the Apollo astronauts."
In the above I've highlighted words about Earth's spin because page 231 in the before mentioned Steve Jones book (see Post 48) has in it this related statement:
"Even the days of the Earth have changed. As the moon saps its neighbor's rotational energy, the globe slows its spin. Corals have daily and annual rings of activity, and growth rings from four hundred million years ago show that there were then four hundred days a year."